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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Ducci%2C+L&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Ducci%2C+L&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Ducci%2C+L&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Ducci%2C+L&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.02092">arXiv:2411.02092</a> <span> [<a href="https://arxiv.org/pdf/2411.02092">pdf</a>, <a href="https://arxiv.org/format/2411.02092">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Searching for orbital period modulation in X-ray observations of the symbiotic X-ray binary GX 1+4 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Klawin%2C+M">Moritz Klawin</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+M+M">M. Mirac Serim</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">Carlo Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">Enrico Bozzo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.02092v1-abstract-short" style="display: inline;"> The symbiotic X-ray binary GX 1+4 possesses a number of peculiar properties that have been studied since the early 1970s. In particular, the orbital period has been a point of debate for many years, until radial velocity measurements were able to settle the debate. These radial velocity findings have so far not been confirmed using X-ray data, even though multiple factors would cause a periodic va… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.02092v1-abstract-full').style.display = 'inline'; document.getElementById('2411.02092v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.02092v1-abstract-full" style="display: none;"> The symbiotic X-ray binary GX 1+4 possesses a number of peculiar properties that have been studied since the early 1970s. In particular, the orbital period has been a point of debate for many years, until radial velocity measurements were able to settle the debate. These radial velocity findings have so far not been confirmed using X-ray data, even though multiple factors would cause a periodic variation on the same timescale as the orbital period at these energies. Because the orbit of GX 1+4 is eccentric and not seen face-on, changes in the accretion rate and column density along the line of sight could cause a periodic variation in the spin-frequency measurements, X-ray light curves, and hardness ratios of the source. Furthermore, for a high inclination of the orbital plane, the neutron star could be eclipsed by the companion, which would lead to periodic decreases in brightness. We used data from a number of different X-ray telescopes to search directly for periodicity by applying the Lomb-Scargle and epoch-folding approaches to long-term light-curve and spin-frequency measurement data of the source. We support our findings using folded light curves, hardness ratios, and images. We find that our results agree with the radial velocity findings, and we form a self-consistent model that is supported by folded hardness-ratios and light curves. We find that the source is clearly detected in X-rays during the predicted eclipse. Motivated by this absence of an eclipse in the system, we constrain the inclination of the system to $\sim 76^\circ-84^\circ$ and the mass of the neutron star in the system to $\sim1.23M_\odot - 1.45M_\odot$ using the constraints on the red giant mass and surface gravity provided in the literature. Furthermore, we constrain the radius of the red giant to $\sim 60R_\odot - 150R_\odot$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.02092v1-abstract-full').style.display = 'none'; document.getElementById('2411.02092v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 8 figures, to be published in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.23484">arXiv:2410.23484</a> <span> [<a href="https://arxiv.org/pdf/2410.23484">pdf</a>, <a href="https://arxiv.org/format/2410.23484">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> INTEGRAL observations of magnetars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Pacholski%2C+D+P">Dominik P. Pacholski</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Topinka%2C+M">Martin Topinka</a>, <a href="/search/astro-ph?searchtype=author&query=Mereghetti%2C+S">Sandro Mereghetti</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.23484v1-abstract-short" style="display: inline;"> The INTEGRAL satellite has collected a large amount of data on magnetars in our Galaxy, spanning more than 20 years starting from 2003. The large data set obtained with the IBIS/ISGRI instrument at energies above 20 keV allows us to study both the properties and long-term evolution of their persistent hard X-ray emission and the population characteristics of the short bursts emitted during active… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23484v1-abstract-full').style.display = 'inline'; document.getElementById('2410.23484v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.23484v1-abstract-full" style="display: none;"> The INTEGRAL satellite has collected a large amount of data on magnetars in our Galaxy, spanning more than 20 years starting from 2003. The large data set obtained with the IBIS/ISGRI instrument at energies above 20 keV allows us to study both the properties and long-term evolution of their persistent hard X-ray emission and the population characteristics of the short bursts emitted during active periods. We are carrying out a comprehensive analysis of the observed magnetars, exploiting the most recent calibrations and analysis software. Here we report on the long term evolution of the hard X-ray flux of the magnetars detected with ISGRI and the results of a sensitive search for short bursts in SGR J1935+2154. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23484v1-abstract-full').style.display = 'none'; document.getElementById('2410.23484v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 5 figures. Accepted for publication in Astronomische Nachrichten, Proceedings of the XMM-Newton 2024 Science Workshop</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.22859">arXiv:2410.22859</a> <span> [<a href="https://arxiv.org/pdf/2410.22859">pdf</a>, <a href="https://arxiv.org/format/2410.22859">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202451062">10.1051/0004-6361/202451062 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The high-energy cyclotron line in 2S 1417-624 discovered with Insight-HXMT during the 2018 outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Q">Q. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Kong%2C+L+D">L. D. Kong</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+W">W. Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+M+M">M. M. Serim</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%BCng%C3%B6r%2C+C">C. G眉ng枚r</a>, <a href="/search/astro-ph?searchtype=author&query=Tuo%2C+Y+L">Y. L. Tuo</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+D">D. Serim</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.22859v1-abstract-short" style="display: inline;"> We report a detailed timing and spectral analysis of the X-ray pulsar 2S~1417-624 using the data from Insight-HXMT during the 2018 outburst. The pulse profiles are highly variable with respect to both unabsorbed flux and energy. A double-peaked pulse profile from the low flux evolved to a multi-peaked shape in the high-flux state. The pulse fraction is negatively correlated to the source flux in t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22859v1-abstract-full').style.display = 'inline'; document.getElementById('2410.22859v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.22859v1-abstract-full" style="display: none;"> We report a detailed timing and spectral analysis of the X-ray pulsar 2S~1417-624 using the data from Insight-HXMT during the 2018 outburst. The pulse profiles are highly variable with respect to both unabsorbed flux and energy. A double-peaked pulse profile from the low flux evolved to a multi-peaked shape in the high-flux state. The pulse fraction is negatively correlated to the source flux in the range of $\sim$(1--6)$\ \times \ 10^{-9}$ erg cm$^{-2}$ s$^{-1}$, consistent with \textit{Rossi} X-ray Timing Explorer (RXTE) studies during the 2009 giant outburst. The energy-resolved pulse profiles around the peak outburst showed a four-peak shape in the low-energy bands and gradually evolved to triple peaks at higher energies. The continuum spectrum is well described by typical phenomenological models, such as the cut-off power law and the power law with high-energy cut-off models. Notably, we discovered high-energy cyclotron resonant scattering features (CRSFs) for the first time, which are around 100 keV with a statistical significance of $\sim$7$蟽$ near the peak luminosity of the outburst. This CRSF line is significantly detected with different continuum models and provides very robust evidence for its presence. Furthermore, pulse-phase-resolved spectroscopy confirmed the presence of the line, whose energy varied from 97 to 107 keV over the pulse phase and appeared to have a maximum value at the narrow peak phase of the profiles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22859v1-abstract-full').style.display = 'none'; document.getElementById('2410.22859v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics, 10 pages, 10 figures and 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.22218">arXiv:2410.22218</a> <span> [<a href="https://arxiv.org/pdf/2410.22218">pdf</a>, <a href="https://arxiv.org/format/2410.22218">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202349098">10.1051/0004-6361/202349098 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Temporal and spectral variations of the X-ray pulsar Cen X-3 observed by NuSTAR </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Liu%2C+Q">Qi Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+W">Wei Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Kong%2C+L">Lingda Kong</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">Long Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.22218v1-abstract-short" style="display: inline;"> We report a time-resolved analysis of the accreting X-ray pulsar Cen X-3 using observations carried out by NuSTAR, which cover approximately two binary orbits in different intensity states. The pulse profile is relatively stable over the orbital phase and shows energy dependence. It has an obvious double-peaked shape in the energy band below 15 keV -- with the second pulse peak decreasing as energ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22218v1-abstract-full').style.display = 'inline'; document.getElementById('2410.22218v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.22218v1-abstract-full" style="display: none;"> We report a time-resolved analysis of the accreting X-ray pulsar Cen X-3 using observations carried out by NuSTAR, which cover approximately two binary orbits in different intensity states. The pulse profile is relatively stable over the orbital phase and shows energy dependence. It has an obvious double-peaked shape in the energy band below 15 keV -- with the second pulse peak decreasing as energy increases -- and is gradually dominated by a single peak in higher energy bands. We find that the pulse profile in the energy band of 3-5 keV at high-intensity states shows a subtle triple-peaked shape, with the main peak divided into two subpeaks. We also find a positive correlation between the pulse fraction and both energy and flux. Our spectral analysis reveals that the spectra can be well described by the continuum of Fermi-Dirac cutoff and NPEX models, and the cyclotron line is detected with the centroid energies varying from 26 keV to 29 keV, along with the iron emission line around 6.4 keV. We investigated the dependence between the cyclotron resonant scattering feature (CRSF) centroid energy and luminosity and discuss the theoretical critical luminosity. Although the variation of $E_{\rm cyc}- L_X$ is not distinct, there is a possibility that the critical luminosity lies within the range of $\sim (0.5-4)\times 10^{37}$ erg s$^{-1}$ in the band of $4-78$ keV. The photon index shows a strong positive correlation with luminosity. Our orbital-phase analysis reveals that the spectral parameters show orbital variability, and the highly variable photoelectric absorption may indicate the existence of clumpy stellar winds. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22218v1-abstract-full').style.display = 'none'; document.getElementById('2410.22218v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A, 687, A210 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.18606">arXiv:2410.18606</a> <span> [<a href="https://arxiv.org/pdf/2410.18606">pdf</a>, <a href="https://arxiv.org/format/2410.18606">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> XMM-Newton observations of the peculiar Be X-ray binary A0538-66 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rigoselli%2C+M">Michela Rigoselli</a>, <a href="/search/astro-ph?searchtype=author&query=Tresoldi%2C+C">Caterina Tresoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Mereghetti%2C+S">Sandro Mereghetti</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.18606v1-abstract-short" style="display: inline;"> A0538-66 is a neutron star/Be X-ray binary located in the Large Magellanic Cloud and, since its discovery in the seventies, it showed a peculiar behavior which makes it a unique object in the high-mass X-ray binaries scene: the extremely eccentric orbit (e=0.72), the short spin period of the neutron star (P=69 ms), the episodes of super-Eddington accretion. These characteristics contribute to a re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.18606v1-abstract-full').style.display = 'inline'; document.getElementById('2410.18606v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.18606v1-abstract-full" style="display: none;"> A0538-66 is a neutron star/Be X-ray binary located in the Large Magellanic Cloud and, since its discovery in the seventies, it showed a peculiar behavior which makes it a unique object in the high-mass X-ray binaries scene: the extremely eccentric orbit (e=0.72), the short spin period of the neutron star (P=69 ms), the episodes of super-Eddington accretion. These characteristics contribute to a remarkable bursting activity that lasts from minutes to hours and increases the flux by a factor 10^3-10^4. In 2018, A0538-66 was observed by XMM-Newton in a particularly active state, characterized by a forest of short bursts lasting 0.7-50 seconds each. In this contribution we present a reanalysis of these observations. The timing analysis allowed us to distinguish between the epochs of direct accretion and propeller state, that do not correlate with the orbital position of the neutron star. The spectral analysis revealed that during the accretion regime three components (a soft one, a hard one, and a ~6.4-keV emission line) equally contribute to the overall emission, while the propeller regime is characterized by a single soft component. We discuss these findings in the context of spherical and disk accretion regimes, highlighting the similarities and the differences with other X-ray binary systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.18606v1-abstract-full').style.display = 'none'; document.getElementById('2410.18606v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in the proceedings of the XMM-Newton 2024 Science Workshop (Astronomische Nachrichten), 7 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.05535">arXiv:2409.05535</a> <span> [<a href="https://arxiv.org/pdf/2409.05535">pdf</a>, <a href="https://arxiv.org/format/2409.05535">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Searching for redshifted 2.2 MeV neutron-capture lines from accreting neutron stars: Theoretical X-ray luminosity requirements and INTEGRAL/SPI observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Tsygankov%2C+S">S. Tsygankov</a>, <a href="/search/astro-ph?searchtype=author&query=Mushtukov%2C+A">A. Mushtukov</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">C. Ferrigno</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.05535v1-abstract-short" style="display: inline;"> Accreting neutron stars (NSs) are expected to emit a redshifted 2.2 MeV line due to the capture of neutrons produced through the spallation processes of $^4$He and heavier ions in their atmospheres. Detecting this emission would offer an independent method for constraining the equation of state of NSs and provide valuable insights into nuclear reactions occurring in extreme gravitational and magne… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05535v1-abstract-full').style.display = 'inline'; document.getElementById('2409.05535v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.05535v1-abstract-full" style="display: none;"> Accreting neutron stars (NSs) are expected to emit a redshifted 2.2 MeV line due to the capture of neutrons produced through the spallation processes of $^4$He and heavier ions in their atmospheres. Detecting this emission would offer an independent method for constraining the equation of state of NSs and provide valuable insights into nuclear reactions occurring in extreme gravitational and magnetic environments. Typically, a higher mass accretion rate is expected to result in a higher 2.2 MeV line intensity. However, when the mass accretion rate approaches the critical threshold, the accretion flow is decelerated by the radiative force, leading to a less efficient production of free neutrons and a corresponding drop in the flux of the spectral line. This makes the brightest X-ray pulsars unsuitable candidates for gamma-ray line detection. In this work, we present a theoretical framework for predicting the optimal X-ray luminosity required to detect a redshifted 2.2 MeV line in a strongly magnetized NS. As the INTEGRAL mission nears its conclusion, we have undertaken a thorough investigation of the SPI data of this line in a representative sample of accreting NSs. No redshifted 2.2 MeV line was detected. For each spectrum, we have determined the 3-sigma upper limits of the line intensity, assuming different values of the line width. Our findings suggest that advancing our understanding of the emission mechanism of the 2.2 MeV line, as well as the accretion flow responsible for it, will require a substantial increase in sensitivity from future MeV missions. For example, for a bright X-ray binary such as Sco X-1, we would need at least a 3-sigma line point source sensitivity of ~1E-6 ph/cm^2/s, that is, about two orders of magnitude better than that currently achieved. [Abridged] <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05535v1-abstract-full').style.display = 'none'; document.getElementById('2409.05535v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.14171">arXiv:2408.14171</a> <span> [<a href="https://arxiv.org/pdf/2408.14171">pdf</a>, <a href="https://arxiv.org/format/2408.14171">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202451195">10.1051/0004-6361/202451195 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Soft X-ray emission from the classical nova AT 2018bej </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Tavleev%2C+A">A. Tavleev</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">V. F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Maitra%2C+C">C. Maitra</a>, <a href="/search/astro-ph?searchtype=author&query=Werner%2C+K">K. Werner</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.14171v2-abstract-short" style="display: inline;"> Classical novae are known to demonstrate a supersoft X-ray source (SSS) state following outbursts, which is associated with residual thermonuclear burning on the white dwarf (WD) surface. During its all-sky survey (eRASS1), the eROSITA telescope onboard the Spectrum-Roentgen-Gamma observatory discovered a bright new SSS, whose position is consistent with the known classical nova AT 2018bej in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14171v2-abstract-full').style.display = 'inline'; document.getElementById('2408.14171v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.14171v2-abstract-full" style="display: none;"> Classical novae are known to demonstrate a supersoft X-ray source (SSS) state following outbursts, which is associated with residual thermonuclear burning on the white dwarf (WD) surface. During its all-sky survey (eRASS1), the eROSITA telescope onboard the Spectrum-Roentgen-Gamma observatory discovered a bright new SSS, whose position is consistent with the known classical nova AT 2018bej in the Large Magellanic Cloud. There were two eROSITA spectra obtained during eRASS1 and eRASS2 monitoring epochs and one XMM-Newton grating spectrum close to the eRASS1 epoch. We aim to describe the eROSITA and XMM-Newton spectra of AT 2018bej with our local thermodynamic equilibrium (LTE) atmosphere models. We focused on the evolution of the hot WD properties between the eRASS1 and eRASS2 epochs, especially on the change of the carbon abundance. A grid of LTE model atmosphere spectra were calculated for different values of the effective temperature (from $T_{\rm eff}= 525$ to $700\,\rm kK$), surface gravity (six values) and chemical composition with five different values of carbon and nitrogen abundances. Both eRASS1 and XMM $0.3-0.6$ keV spectral analyses yield a temperature of the WD of $T_{\rm eff}{\sim}\,600\, \rm kK$ and a WD radius of $8000-8700\,\rm km$. Simultaneous fitting of the eROSITA spectra for two epochs (eRASS1 and eRASS2) with a common WD mass parameter demonstrates a decrease in $T_{\rm eff}$ accompanied by an increase in the WD radius and a decrease in the carbon abundance. However, these changes are marginal and coincide within errors. The derived WD mass is estimated to be $1.05-1.15\, M_\odot$. We traced a minor evolution of the source on a half-year timescale accompanied by a decrease in carbon abundance and concluded that LTE model atmospheres can be used to analyse the available X-ray spectra of classical novae during their SSS stage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14171v2-abstract-full').style.display = 'none'; document.getElementById('2408.14171v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 16 figures, accepted for publication to A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A335 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.18158">arXiv:2404.18158</a> <span> [<a href="https://arxiv.org/pdf/2404.18158">pdf</a>, <a href="https://arxiv.org/format/2404.18158">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ad4488">10.3847/2041-8213/ad4488 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of the first anti-glitch event in the rotation-powered pulsar PSR B0540-69 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Tuo%2C+Y">Youli Tuo</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+M+M">M. M. Serim</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+M">Marco Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Vahdat%2C+A">Armin Vahdat</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M">Mingyu Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.18158v2-abstract-short" style="display: inline;"> Using data from the Neutron star Interior Composition ExploreR (NICER) observatory, we identified a permanent spin frequency decrease of $螖谓=-(1.04\pm0.07)\times 10^{-7}\,\mathrm{Hz}$ around MJD 60132 in the rotation-powered pulsar PSR B0540-69, which exhibits a periodic signal at a frequency of $谓\sim 19.6\,\mathrm{Hz}$. This points to an anti-glitch event, a sudden decrease of the pulsar's rotat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.18158v2-abstract-full').style.display = 'inline'; document.getElementById('2404.18158v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.18158v2-abstract-full" style="display: none;"> Using data from the Neutron star Interior Composition ExploreR (NICER) observatory, we identified a permanent spin frequency decrease of $螖谓=-(1.04\pm0.07)\times 10^{-7}\,\mathrm{Hz}$ around MJD 60132 in the rotation-powered pulsar PSR B0540-69, which exhibits a periodic signal at a frequency of $谓\sim 19.6\,\mathrm{Hz}$. This points to an anti-glitch event, a sudden decrease of the pulsar's rotational frequency without any major alteration in the pulse profile or any significant increase of the pulsed flux. Additionally, no burst activity was observed in association with the anti-glitch. To date, observations of the few known anti-glitches have been made in magnetars or accreting pulsars. This is the first anti-glitch detected in a rotation-powered pulsar. Given its radiatively quiet nature, this anti-glitch is possibly of internal origin. Therefore, we tentatively frame this event within a proposed mechanism for anti-glitches where the partial `evaporation' of the superfluid component leads to an increase of the normal component's moment of inertia and a decrease of the superfluid one. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.18158v2-abstract-full').style.display = 'none'; document.getElementById('2404.18158v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 4 figures, accepted for publication in ApJL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.13127">arXiv:2403.13127</a> <span> [<a href="https://arxiv.org/pdf/2403.13127">pdf</a>, <a href="https://arxiv.org/format/2403.13127">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Timing analysis of the newly discovered black hole candidate Swift J1727.8-1613 with Insight-HXMT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Yu%2C+W">Wei Yu</a>, <a href="/search/astro-ph?searchtype=author&query=Bu%2C+Q">Qing-Cui Bu</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shuang-Nan Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+H">He-Xin Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+L">Liang Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Tao%2C+L">Lian Tao</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Huang%2C+Y">Yue Huang</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+Z">Zi-Xu Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+J">Jin-Lu Qu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.13127v1-abstract-short" style="display: inline;"> We present the results obtained from an X-ray timing study of the new black hole candidate (BHC) Swift J1727.8-1613. The work is based on Hard X-ray Modulation Telescope (Insight-HXMT) observations carried out during the 2023 outburst. Prominent type-C low-frequency Quasi-periodic Oscillations (LFQPOs) are detected throughout the observations. With the substantial effective area of the Insight-HXM… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13127v1-abstract-full').style.display = 'inline'; document.getElementById('2403.13127v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.13127v1-abstract-full" style="display: none;"> We present the results obtained from an X-ray timing study of the new black hole candidate (BHC) Swift J1727.8-1613. The work is based on Hard X-ray Modulation Telescope (Insight-HXMT) observations carried out during the 2023 outburst. Prominent type-C low-frequency Quasi-periodic Oscillations (LFQPOs) are detected throughout the observations. With the substantial effective area of the Insight-HXMT at high energies, we examine the energy dependence of various parameters, including the centroid frequency, fractional rms, and phase lags of the type-C QPOs. Our findings align closely with those observed in high-inclination systems. During the initial stage of the outburst, a peaked noise component is also detected, the frequency of which is highly correlated with the LFQPO frequency, aligning with the Psaltis-Belloni-van der Klis (PBK) relation. By assuming that the peaked noise originates from the precession of the accretion disc, the spin of this source can be constrained. Our results suggest that this source may possess a high spin. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13127v1-abstract-full').style.display = 'none'; document.getElementById('2403.13127v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.04857">arXiv:2403.04857</a> <span> [<a href="https://arxiv.org/pdf/2403.04857">pdf</a>, <a href="https://arxiv.org/format/2403.04857">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1475-7516/2024/07/047">10.1088/1475-7516/2024/07/047 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dark Matter Line Searches with the Cherenkov Telescope Array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abhir%2C+J">J. Abhir</a>, <a href="/search/astro-ph?searchtype=author&query=Abhishek%2C+A">A. Abhishek</a>, <a href="/search/astro-ph?searchtype=author&query=Acero%2C+F">F. Acero</a>, <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adam%2C+R">R. Adam</a>, <a href="/search/astro-ph?searchtype=author&query=Aguasca-Cabot%2C+A">A. Aguasca-Cabot</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aguirre-Santaella%2C+A">A. Aguirre-Santaella</a>, <a href="/search/astro-ph?searchtype=author&query=Alfaro%2C+J">J. Alfaro</a>, <a href="/search/astro-ph?searchtype=author&query=Alfaro%2C+R">R. Alfaro</a>, <a href="/search/astro-ph?searchtype=author&query=Alvarez-Crespo%2C+N">N. Alvarez-Crespo</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+R+A">R. Alves Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Amans%2C+J+-">J. -P. Amans</a>, <a href="/search/astro-ph?searchtype=author&query=Amato%2C+E">E. Amato</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">G. Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Angel%2C+L">L. Angel</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">C. Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Arnesen%2C+T+T+H">T. T. H. Arnesen</a>, <a href="/search/astro-ph?searchtype=author&query=Arrabito%2C+L">L. Arrabito</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Ascasibar%2C+Y">Y. Ascasibar</a>, <a href="/search/astro-ph?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/astro-ph?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a> , et al. (540 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.04857v2-abstract-short" style="display: inline;"> Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of sele… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.04857v2-abstract-full').style.display = 'inline'; document.getElementById('2403.04857v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.04857v2-abstract-full" style="display: none;"> Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g.~box-shaped spectra, that would likewise very clearly point to a particle dark matter origin. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.04857v2-abstract-full').style.display = 'none'; document.getElementById('2403.04857v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">44 pages JCAP style (excluding author list and references), 19 figures; minor changes to match published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> JCAP 07 (2024) 047 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.01941">arXiv:2403.01941</a> <span> [<a href="https://arxiv.org/pdf/2403.01941">pdf</a>, <a href="https://arxiv.org/ps/2403.01941">ps</a>, <a href="https://arxiv.org/format/2403.01941">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202349033">10.1051/0004-6361/202349033 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing the emission mechanism and nature of the pulsating compact object in the X-ray binary SAX J1324.4-6200 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">E. Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Burgay%2C+M">M. Burgay</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">C. Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Ridolfi%2C+A">A. Ridolfi</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+M+M">M. M. Serim</a>, <a href="/search/astro-ph?searchtype=author&query=Vercellone%2C+S">S. Vercellone</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.01941v1-abstract-short" style="display: inline;"> Recently, there has been renewed interest in the Be X-ray binary (Be/XRB) SAX J1324.4-6200 because of its spatial coincidence with a gamma-ray source detected by Fermi/LAT. To explore more thoroughly its properties, new observations were carried out in 2023 by NuSTAR, XMM-Newton, and Swift, jointly covering the energy range 0.2-79 keV. The X-ray spectrum of SAX J1324.4-6200 fits well with an absor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.01941v1-abstract-full').style.display = 'inline'; document.getElementById('2403.01941v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.01941v1-abstract-full" style="display: none;"> Recently, there has been renewed interest in the Be X-ray binary (Be/XRB) SAX J1324.4-6200 because of its spatial coincidence with a gamma-ray source detected by Fermi/LAT. To explore more thoroughly its properties, new observations were carried out in 2023 by NuSTAR, XMM-Newton, and Swift, jointly covering the energy range 0.2-79 keV. The X-ray spectrum of SAX J1324.4-6200 fits well with an absorbed power law with a high energy cut-off. We measured a NuSTAR spin period of 175.8127 +/- 0.0036 s and an XMM-Newton spin period of 175.862 +/- 0.025 s. All the available spin period measurements of SAX J1324.4-6200, spanning 29 years, are correlated with time, resulting in a remarkably stable spin-down of dP/dt=(6.09 +/- 0.06)*1E-9 s/s. If SAX J1324.4-6200 hosts an accretion powered pulsar, accretion torque models indicate a surface magnetic field of ~1E12-1E13 G. The X-ray properties emerging from our analysis strenghten the hypothesis that SAX J1324.4-6200 belongs to the small group of persistent Be/XRBs. We also performed radio observations with the Parkes Murriyang telescope, to search for radio pulsations. However, no radio pulsations compatible with the rotational ephemeris of SAX J1324.4-6200 were detected. We rule out the hypothesis that SAX J1324.4-6200 is a gamma-ray binary where the emission is produced by interactions between the pulsar and the companion winds. Other models commonly used to account for the production of gamma-rays in accreting pulsars cannot reproduce the bright emission from SAX J1324.4-6200. We examined other mechanisms for the gamma-ray emission and noted that there is a ~0.5% chance probability that an unknown extragalactic AGN observed through the Galactic plane may coincidentally fall within the Fermi/LAT error circle of the source and be the responsible of the gamma-ray emission. [Abridged] <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.01941v1-abstract-full').style.display = 'none'; document.getElementById('2403.01941v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy and Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 685, A148 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.16239">arXiv:2401.16239</a> <span> [<a href="https://arxiv.org/pdf/2401.16239">pdf</a>, <a href="https://arxiv.org/format/2401.16239">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> The polarization of the boundary layer around weakly magnetized neutron stars in X-ray binaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Farinelli%2C+R">R. Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Waghmare%2C+A">A. Waghmare</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.16239v1-abstract-short" style="display: inline;"> X-ray binaries hosting a compact object have been among the main targets of the Imaging X-ray Polarimetry Explorer (IXPE) since its launch, due to their high brightness in the 2-8 keV energy band. The spectropolarimetric analysis performed so far has proved to be of great importance in providing constraints on the accretion geometry of these systems. However, the data statistics is not enough to u… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.16239v1-abstract-full').style.display = 'inline'; document.getElementById('2401.16239v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.16239v1-abstract-full" style="display: none;"> X-ray binaries hosting a compact object have been among the main targets of the Imaging X-ray Polarimetry Explorer (IXPE) since its launch, due to their high brightness in the 2-8 keV energy band. The spectropolarimetric analysis performed so far has proved to be of great importance in providing constraints on the accretion geometry of these systems. However, the data statistics is not enough to unambiguously disentangle the contribution of the single components to the net observed polarimetric signal. In this work, we aim to present a model for computing the polarization degree and polarization angle of the boundary layer around weakly magnetized neutron stars in low-mass X-ray binaries in the soft state. The main motivation is to provide strong theoretical support to data interpretation of observations performed by IXPE or future satellites for X-ray polarimetry. The results were obtained by modeling the boundary layer as an equatorial belt around the compact object and locally approximating it as a plane-parallel scattering atmosphere, for which the associated radiative transfer equation for polarized radiation in the Thomson limit was solved. The polarimetric quantities were then transformed from the comoving frame to the observer frame using the numerical methods formerly developed for X-ray pulsars. For typical values of the optical depth and electron temperature of the boundary layer of these systems in a soft state, the polarization degree was less then 0.5\%, while the polarization angle was rotated by $\protect \la 5^{\circ}$ with respect to the neutron star spin axis due to special and general relativistic effects for fast rotation, the amount progressively decreasing for lower spin frequencies. The derived quantities can be used to remove degeneracy when multicomponent spectropolarimetry is performed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.16239v1-abstract-full').style.display = 'none'; document.getElementById('2401.16239v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 8 figures, accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.02658">arXiv:2401.02658</a> <span> [<a href="https://arxiv.org/pdf/2401.02658">pdf</a>, <a href="https://arxiv.org/format/2401.02658">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Correlated spectro-polarimetric study along the Z track in XTE J1701-462 puts constraints on its coronal geometry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Yu%2C+W">Wei Yu</a>, <a href="/search/astro-ph?searchtype=author&query=Bu%2C+Q">Qingcui Bu</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">Long Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+W">Wenda Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shuangnan Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Waghmare%2C+A">Anand Waghmare</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M">Mingyu Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Huang%2C+Y">Yue Huang</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+H">Hexin Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Tao%2C+L">Lian Tao</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+Z">Zixu Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+L">Liang Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+J">Jinlu Qu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.02658v2-abstract-short" style="display: inline;"> Context. In September 2022, the transient neutron star low-mass X-ray binary XTE J1701-462 went into a new outburst. Aims. The objective of this work is to examine the evolution of the accretion geometry of XTE J1701-462 by studying the spectro-polarimetric properties along the Z track of this source. The simultaneous observations archived by the Insight-Hard X-ray Modulation Telescope (HXMT) and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.02658v2-abstract-full').style.display = 'inline'; document.getElementById('2401.02658v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.02658v2-abstract-full" style="display: none;"> Context. In September 2022, the transient neutron star low-mass X-ray binary XTE J1701-462 went into a new outburst. Aims. The objective of this work is to examine the evolution of the accretion geometry of XTE J1701-462 by studying the spectro-polarimetric properties along the Z track of this source. The simultaneous observations archived by the Insight-Hard X-ray Modulation Telescope (HXMT) and the Imaging X-ray Polarimetry Explorer (IXPE) give us the opportunity. Methods. We present a comprehensive X-ray spectro-polarimetric analysis of XTE J1701-462, using simultaneous observations from IXPE, Insight-HXMT and NuSTAR. For IXPE observations, two methods are employed to measure the polarization: a model-independent measurement with PCUBE and a model-dependent polarization-spectral analysis with XSPEC. The corresponding spectra from Insight-HXMT and NuSTAR are studied with two configurations that correspond to a slab-like corona and a spherical shell-like corona, respectively. Results. Significant polarization characteristics are detected in XTE J1701-462. The polarization degree shows a decreasing trend along the Z track, reducing from (4.84 $\pm$ 0.37)% to (3.76 $\pm$ 0.43)% on the horizontal branch and jumping to less than 1% on the normal branch. The simultaneous spectral analysis from Insight-HXMT and NuSTAR suggests that the evolution of the PD is closely linked to changes in the flux of the Comptonized component and its covering factor along the Z track, supporting a shrinking corona. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.02658v2-abstract-full').style.display = 'none'; document.getElementById('2401.02658v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.16937">arXiv:2312.16937</a> <span> [<a href="https://arxiv.org/pdf/2312.16937">pdf</a>, <a href="https://arxiv.org/format/2312.16937">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Timing and Spectral Analysis of HMXB 4U 1700-37 Observed with Insight-HXMT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Xiao%2C+H">Hua Xiao</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">Long Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+P">Peng Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shu Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shuang-Nan Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.16937v4-abstract-short" style="display: inline;"> We report timing and spectral studies of the high mass X-ray binary 4U 1700-37 using Insight-HXMT observations carried out in 2020 during its out-of-eclipse state. We found significant variations in flux on a time-scale of kilo-seconds, while the hardness (count rate ratio between 10-30 keV and 2-10 keV) remains relatively stable. No evident pulsations were found over a frequency range of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.16937v4-abstract-full').style.display = 'inline'; document.getElementById('2312.16937v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.16937v4-abstract-full" style="display: none;"> We report timing and spectral studies of the high mass X-ray binary 4U 1700-37 using Insight-HXMT observations carried out in 2020 during its out-of-eclipse state. We found significant variations in flux on a time-scale of kilo-seconds, while the hardness (count rate ratio between 10-30 keV and 2-10 keV) remains relatively stable. No evident pulsations were found over a frequency range of $10^{-3}$-2000 Hz. During the spectral analysis, for the first time we took the configuration of different Insight-HXMT detectors' orientations into account, which allows us obtaining reliable results even if a stable contamination exists in the field-of-view. We found that the spectrum could be well described by some phenomenological models that commonly used in accreting pulsars (e.g., a power law with a high energy cutoff) in the energy range of 2-100 keV. We found hints of cyclotron absorption features around ~ 16 keV or/and ~ 50 keV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.16937v4-abstract-full').style.display = 'none'; document.getElementById('2312.16937v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.14645">arXiv:2312.14645</a> <span> [<a href="https://arxiv.org/pdf/2312.14645">pdf</a>, <a href="https://arxiv.org/format/2312.14645">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> A magnetar giant flare in the nearby starburst galaxy M82 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Mereghetti%2C+S">Sandro Mereghetti</a>, <a href="/search/astro-ph?searchtype=author&query=Rigoselli%2C+M">Michela Rigoselli</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">Ruben Salvaterra</a>, <a href="/search/astro-ph?searchtype=author&query=Pacholski%2C+D+P">Dominik P. Pacholski</a>, <a href="/search/astro-ph?searchtype=author&query=Rodi%2C+J+C">James C. Rodi</a>, <a href="/search/astro-ph?searchtype=author&query=Gotz%2C+D">Diego Gotz</a>, <a href="/search/astro-ph?searchtype=author&query=Arrigoni%2C+E">Edoardo Arrigoni</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Avanzo%2C+P">Paolo D'Avanzo</a>, <a href="/search/astro-ph?searchtype=author&query=Adami%2C+C">Christophe Adami</a>, <a href="/search/astro-ph?searchtype=author&query=Bazzano%2C+A">Angela Bazzano</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">Enrico Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Brivio%2C+R">Riccardo Brivio</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">Sergio Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Cappellaro%2C+E">Enrico Cappellaro</a>, <a href="/search/astro-ph?searchtype=author&query=Chenevez%2C+J">Jerome Chenevez</a>, <a href="/search/astro-ph?searchtype=author&query=De+Luise%2C+F">Fiore De Luise</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Esposito%2C+P">Paolo Esposito</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">Carlo Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Ferro%2C+M">Matteo Ferro</a>, <a href="/search/astro-ph?searchtype=author&query=Israel%2C+G+L">Gian Luca Israel</a>, <a href="/search/astro-ph?searchtype=author&query=Floc%27h%2C+E+L">Emeric Le Floc'h</a>, <a href="/search/astro-ph?searchtype=author&query=Martin-Carrillo%2C+A">Antonio Martin-Carrillo</a>, <a href="/search/astro-ph?searchtype=author&query=Onori%2C+F">Francesca Onori</a>, <a href="/search/astro-ph?searchtype=author&query=Rea%2C+N">Nanda Rea</a> , et al. (10 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.14645v2-abstract-short" style="display: inline;"> Giant flares, short explosive events releasing up to 10$^{47}$ erg of energy in the gamma-ray band in less than one second, are the most spectacular manifestation of magnetars, young neutron stars powered by a very strong magnetic field, 10$^{14-15}$ G in the magnetosphere and possibly higher in the star interior. The rate of occurrence of these rare flares is poorly constrained, as only three hav… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.14645v2-abstract-full').style.display = 'inline'; document.getElementById('2312.14645v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.14645v2-abstract-full" style="display: none;"> Giant flares, short explosive events releasing up to 10$^{47}$ erg of energy in the gamma-ray band in less than one second, are the most spectacular manifestation of magnetars, young neutron stars powered by a very strong magnetic field, 10$^{14-15}$ G in the magnetosphere and possibly higher in the star interior. The rate of occurrence of these rare flares is poorly constrained, as only three have been seen from three different magnetars in the Milky Way and in the Large Magellanic Cloud in about 50 years since the beginning of gamma-ray astronomy. This sample can be enlarged by the discovery of extragalactic events, since for a fraction of a second giant flares reach peak luminosities above 10$^{46}$ erg/s, which makes them visible by current instruments up to a few tens of Mpc. However, at these distances they appear similar to, and difficult to distinguish from, regular short gamma-ray bursts (GRBs). The latter are much more energetic events, 10$^{50-53}$ erg, produced by compact binary mergers and originating at much larger distances. Indeed, only a few short GRBs have been proposed, with different levels of confidence, as magnetar giant flare candidates in nearby galaxies. Here we report the discovery of a short GRB positionally coincident with the central region of the starburst galaxy M82. Its spectral and timing properties, together with the limits on its X-ray and optical counterparts obtained a few hours after the event and the lack of an associated gravitational wave signal, qualify with high confidence this event as a giant flare from a magnetar in M82. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.14645v2-abstract-full').style.display = 'none'; document.getElementById('2312.14645v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted version. New figures. Accepted for publication in Nature with minor modifications</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.08943">arXiv:2312.08943</a> <span> [<a href="https://arxiv.org/pdf/2312.08943">pdf</a>, <a href="https://arxiv.org/format/2312.08943">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202450683">10.1051/0004-6361/202450683 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pulse frequency variations and timing noise of MXB 0656-072 during the 2007-2008 type I outbursts and implications for its magnetic field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Serim%2C+M+M">M. Mirac Serim</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+D">Danjela Serim</a>, <a href="/search/astro-ph?searchtype=author&query=D%C3%B6nmez%2C+%C3%87+K">脟a臒atay Kerem D枚nmez</a>, <a href="/search/astro-ph?searchtype=author&query=Tuo%2C+Y">Youli Tuo</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Baykal%2C+A">Altan Baykal</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.08943v2-abstract-short" style="display: inline;"> We aim to explore the properties of the Be/X-ray binary system MXB 0656-072 from a timing analysis perspective through an investigation of the RXTE/PCA and Fermi/GBM data during its 2007-2008 type I outbursts. We applied two new techniques, for the first time, along with the conventional Deeter method to produce higher-resolution power density spectra (PDS) of the torque fluctuations. We also inve… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.08943v2-abstract-full').style.display = 'inline'; document.getElementById('2312.08943v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.08943v2-abstract-full" style="display: none;"> We aim to explore the properties of the Be/X-ray binary system MXB 0656-072 from a timing analysis perspective through an investigation of the RXTE/PCA and Fermi/GBM data during its 2007-2008 type I outbursts. We applied two new techniques, for the first time, along with the conventional Deeter method to produce higher-resolution power density spectra (PDS) of the torque fluctuations. We also investigated the spin frequency evolution of the source by utilising a pulse timing technique. The PDSs show a red noise pattern, with a steepness of $螕\sim -2$ and a saturation timescale of $\sim$150 d, indicating that MXB 0656-072 is a disc-fed source. With the obtained long term spin frequency evolution, we reveal the torque-luminosity correlation of MXB 0656-072 for the first time. We also demonstrate that the frequency evolution is largely consistent with the Ghosh-Lamb model. In the RXTE/PCA observations, the pulsed emission disappears below $\sim$5$\times 10^{35}$ erg s$^{-1}$, while the profiles remain stable above this value in our analysis time frame. We show that the magnetic field strength deduced from the torque model is compatible with the field strength of the pulsar derived from the cyclotron resonance scattering feature. Utilising the new distance of MXB 0656-072 measured by Gaia, we show that the spectral transition of MXB 0656-072 occurs at a luminosity that matches the expected theoretical transition from the subcritical to supercritical accretion regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.08943v2-abstract-full').style.display = 'none'; document.getElementById('2312.08943v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 5 figures. Accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 690, A5 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.07197">arXiv:2311.07197</a> <span> [<a href="https://arxiv.org/pdf/2311.07197">pdf</a>, <a href="https://arxiv.org/ps/2311.07197">ps</a>, <a href="https://arxiv.org/format/2311.07197">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Swift, NuSTAR, and INTEGRAL observations of the symbiotic X-ray binary IGR J16194-2810 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">E. Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">C. Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.07197v1-abstract-short" style="display: inline;"> We report on a simultaneous observational campaign with both Swift/XRT and NuSTAR targeting the symbiotic X-ray binary IGR J16194-2810. The main goal of the campaign was to investigate the possible presence of cyclotron scattering absorption features in the broad-band spectrum of the source, and help advance our understanding of the process of neutron star formation via the accretion-induced colla… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.07197v1-abstract-full').style.display = 'inline'; document.getElementById('2311.07197v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.07197v1-abstract-full" style="display: none;"> We report on a simultaneous observational campaign with both Swift/XRT and NuSTAR targeting the symbiotic X-ray binary IGR J16194-2810. The main goal of the campaign was to investigate the possible presence of cyclotron scattering absorption features in the broad-band spectrum of the source, and help advance our understanding of the process of neutron star formation via the accretion-induced collapse of a white dwarf. The 1-30 keV spectrum of the source, as measured during our campaign, did not reveal the presence of any statistically significant absorption feature. The spectrum could be well described using a model comprising a thermal black-body hot component, most likely emerging from the surface of the accreting neutron star, and a power-law with no measurable cut-off energy (and affected by a modest absorption column density). Compared to previous analyses in the literature, we could rule out the presence of a colder thermal component emerging from an accretion disk, compatible with the idea that IGR J16194-2810 is a wind-fed binary (as most of the symbiotic X-ray binaries). Our results were strengthened by exploiting the archival XRT and INTEGRAL data, extending the validity of the spectral model used up to 0.3-40 keV and demonstrating that IGR J16194-2810 is unlikely to undergo significant spectral variability over time in the X-ray domain. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.07197v1-abstract-full').style.display = 'none'; document.getElementById('2311.07197v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication on MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.16498">arXiv:2310.16498</a> <span> [<a href="https://arxiv.org/pdf/2310.16498">pdf</a>, <a href="https://arxiv.org/format/2310.16498">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Discovery of spin-phase dependent QPOs in the super-critical accretion regime from the X-ray pulsar RX J0440.9+4431 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">Daniela Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Roberts%2C+O+J">Oliver J. Roberts</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">Enrico Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Jenke%2C+P">Peter Jenke</a>, <a href="/search/astro-ph?searchtype=author&query=Wilson-Hodge%2C+C+A">Colleen A. Wilson-Hodge</a>, <a href="/search/astro-ph?searchtype=author&query=Falanga%2C+M">Maurizio Falanga</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.16498v2-abstract-short" style="display: inline;"> RX J0440.9+4431 is an accreting X-ray pulsar (XRP) that remained relatively unexplored until recently, when major X-ray outburst activity enabled more in-depth studies. Here, we report on the discovery of ${\sim}0.2$ Hz quasi-periodic oscillations (QPOs) from this source observed with $Fermi$-GBM. The appearance of QPOs in RX J0440.9+4431 is thricely transient, that is, QPOs appear only above a ce… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.16498v2-abstract-full').style.display = 'inline'; document.getElementById('2310.16498v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.16498v2-abstract-full" style="display: none;"> RX J0440.9+4431 is an accreting X-ray pulsar (XRP) that remained relatively unexplored until recently, when major X-ray outburst activity enabled more in-depth studies. Here, we report on the discovery of ${\sim}0.2$ Hz quasi-periodic oscillations (QPOs) from this source observed with $Fermi$-GBM. The appearance of QPOs in RX J0440.9+4431 is thricely transient, that is, QPOs appear only above a certain luminosity, only at certain pulse phases (namely corresponding to the peak of its sine-like pulse profile), and only for a few oscillations at time. We argue that this newly discovered phenomenon (appearance of thricely transient QPOs -- or ATTO) occurs if QPOs are fed through an accretion disk whose inner region viscosity is unstable to mass accretion rate and temperature variations. Such variations are triggered when the source switches to the super-critical accretion regime and the emission pattern changes. We also argue that the emission region configuration is likely responsible for the observed QPOs spin-phase dependence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.16498v2-abstract-full').style.display = 'none'; document.getElementById('2310.16498v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 + 2 appendix pages. Accepted on A&A. Proofs version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.07413">arXiv:2310.07413</a> <span> [<a href="https://arxiv.org/pdf/2310.07413">pdf</a>, <a href="https://arxiv.org/format/2310.07413">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Chasing Gravitational Waves with the Cherenkov Telescope Array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Green%2C+J+G">Jarred Gershon Green</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+A">Alessandro Carosi</a>, <a href="/search/astro-ph?searchtype=author&query=Nava%2C+L">Lara Nava</a>, <a href="/search/astro-ph?searchtype=author&query=Patricelli%2C+B">Barbara Patricelli</a>, <a href="/search/astro-ph?searchtype=author&query=Sch%C3%BCssler%2C+F">Fabian Sch眉ssler</a>, <a href="/search/astro-ph?searchtype=author&query=Seglar-Arroyo%2C+M">Monica Seglar-Arroyo</a>, <a href="/search/astro-ph?searchtype=author&query=Consortium%2C+C">Cta Consortium</a>, <a href="/search/astro-ph?searchtype=author&query=%3A"> :</a>, <a href="/search/astro-ph?searchtype=author&query=Abe%2C+K">Kazuki Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">Shotaro Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">Atreya Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adam%2C+R">Remi Adam</a>, <a href="/search/astro-ph?searchtype=author&query=Aguasca-Cabot%2C+A">Arnau Aguasca-Cabot</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Alfaro%2C+J">Jorge Alfaro</a>, <a href="/search/astro-ph?searchtype=author&query=Alvarez-Crespo%2C+N">Nuria Alvarez-Crespo</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+R+A">Rafael Alves Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Amans%2C+J">Jean-Philippe Amans</a>, <a href="/search/astro-ph?searchtype=author&query=Amato%2C+E">Elena Amato</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosino%2C+F">Filippo Ambrosino</a>, <a href="/search/astro-ph?searchtype=author&query=Ang%C3%BCner%2C+E+O">Ekrem Oguzhan Ang眉ner</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio Angelo Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">Carla Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">Cornelia Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Arrabito%2C+L">Luisa Arrabito</a> , et al. (545 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.07413v3-abstract-short" style="display: inline;"> The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.07413v3-abstract-full').style.display = 'inline'; document.getElementById('2310.07413v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.07413v3-abstract-full" style="display: none;"> The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.07413v3-abstract-full').style.display = 'none'; document.getElementById('2310.07413v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Presented at the 38th International Cosmic Ray Conference (ICRC 2023), 2023 (arXiv:2309.08219)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CTA-ICRC/2023/30 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.07577">arXiv:2309.07577</a> <span> [<a href="https://arxiv.org/pdf/2309.07577">pdf</a>, <a href="https://arxiv.org/format/2309.07577">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Modeling and Simulating X-ray Spectra </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">C. Malacaria</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2309.07577v2-abstract-short" style="display: inline;"> X-ray spectroscopy is a powerful technique for the analysis of the energy distribution of X-rays from astrophysical sources. It allows for the study of the properties, composition, and physical processes taking place at the site of emission. X-ray spectral analysis methods are diverse, as they often need to be tailored to the specific type of instrument used to collect the data. In addition, these… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.07577v2-abstract-full').style.display = 'inline'; document.getElementById('2309.07577v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.07577v2-abstract-full" style="display: none;"> X-ray spectroscopy is a powerful technique for the analysis of the energy distribution of X-rays from astrophysical sources. It allows for the study of the properties, composition, and physical processes taking place at the site of emission. X-ray spectral analysis methods are diverse, as they often need to be tailored to the specific type of instrument used to collect the data. In addition, these methods advance together with the improvement of the technology of the telescopes and detectors. Here, we present a compact overview of the common procedures currently employed in this field. We describe the fundamental data structure and the essential auxiliary information required for conducting spectral analysis and we explore some of the most relevant aspects related to statistical and computational challenges in X-ray spectroscopy. Furthermore, we outline some practical scenarios in the context of data reduction, modeling and fitting of spectra, and spectral simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.07577v2-abstract-full').style.display = 'none'; document.getElementById('2309.07577v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Invited chapter for the "Handbook of X-ray and Gamma-ray Astrophysics" (Eds. C. Bambi and A. Santangelo, Springer); typos corrected</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.06061">arXiv:2308.06061</a> <span> [<a href="https://arxiv.org/pdf/2308.06061">pdf</a>, <a href="https://arxiv.org/format/2308.06061">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Modelling the expected very high energy gamma-ray emission from accreting neutron stars in X-ray binaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a>, <a href="/search/astro-ph?searchtype=author&query=Vercellone%2C+S">S. Vercellone</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.06061v1-abstract-short" style="display: inline;"> The detection of gamma-ray emission from accreting pulsars in X-ray binaries (XRBs) has long been sought after. For some high-mass X-ray binaries (HMXBs), marginal detections have recently been reported. Regardless of whether these will be confirmed or not, future telescopes operating in the gamma-ray band could offer the sensitivity needed to achieve solid detections and possibly spectra. In view… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.06061v1-abstract-full').style.display = 'inline'; document.getElementById('2308.06061v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.06061v1-abstract-full" style="display: none;"> The detection of gamma-ray emission from accreting pulsars in X-ray binaries (XRBs) has long been sought after. For some high-mass X-ray binaries (HMXBs), marginal detections have recently been reported. Regardless of whether these will be confirmed or not, future telescopes operating in the gamma-ray band could offer the sensitivity needed to achieve solid detections and possibly spectra. In view of future observational advances, we explored the expected emission above 10 GeV from XRBs, based on the Cheng & Ruderman model, where gamma-ray photons are produced by the decay of pion-0 originated by protons accelerated in the magnetosphere of an accreting pulsar fed by an accretion disc. We improved this model by considering, through Monte Carlo simulations, the development of cascades inside of and outside the accretion disc, taking into account pair and photon production processes that involve interaction with nuclei, X-ray photons from the accretion disc, and the magnetic field. We produced grids of solutions for different input parameter values of the X-ray luminosity (L_x), magnetic field strength (B), and for different properties of the region where acceleration occurs. We found that the gamma-ray luminosity spans more than five orders of magnitude, with a maximum of ~1E35 erg/s. The gamma-ray spectra show a large variety of shapes: some have most of the emission below ~100 GeV, others are harder (emission up to 10-100 TeV). We compared our results with Fermi/LAT and VERITAS detections and upper-limits of two HMXBs: A0535+26 and GROJ1008-57. More consequential comparisons will be possible when more sensitive instruments will be operational in the coming years. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.06061v1-abstract-full').style.display = 'none'; document.getElementById('2308.06061v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.11937">arXiv:2304.11937</a> <span> [<a href="https://arxiv.org/pdf/2304.11937">pdf</a>, <a href="https://arxiv.org/format/2304.11937">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stad1407">10.1093/mnras/stad1407 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Timing analysis of Swift J0243.6+6124 with NICER and Fermi/GBM during the decay phase of the 2017-2018 outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Serim%2C+M+M">M. M. Serim</a>, <a href="/search/astro-ph?searchtype=author&query=D%C3%B6nmez%2C+%C3%87+K">脟. K. D枚nmez</a>, <a href="/search/astro-ph?searchtype=author&query=Serim%2C+D">D. Serim</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Baykal%2C+A">A. Baykal</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.11937v2-abstract-short" style="display: inline;"> We present a timing and noise analysis of the Be/X-ray binary system Swift J0243.6+6124 during its 2017-2018 super-Eddington outburst using NICER/XTI observations. We apply a synthetic pulse timing analysis to enrich the Fermi/GBM spin frequency history of the source with the new measurements from NICER/XTI. We show that the pulse profiles switch from double-peaked to single-peaked when the X-ray… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11937v2-abstract-full').style.display = 'inline'; document.getElementById('2304.11937v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.11937v2-abstract-full" style="display: none;"> We present a timing and noise analysis of the Be/X-ray binary system Swift J0243.6+6124 during its 2017-2018 super-Eddington outburst using NICER/XTI observations. We apply a synthetic pulse timing analysis to enrich the Fermi/GBM spin frequency history of the source with the new measurements from NICER/XTI. We show that the pulse profiles switch from double-peaked to single-peaked when the X-ray luminosity drops below $\sim$$7\times 10^{36}$ erg s$^{-1}$. We suggest that this transitional luminosity is associated with the transition from a pencil beam pattern to a hybrid beam pattern when the Coulomb interactions become ineffective to decelerate the accretion flow, which implies a dipolar magnetic field strength of $\sim$$5\times 10^{12}$ G. We also obtained the power density spectra (PDS) of the spin frequency derivative fluctuations. The red noise component of the PDS is found to be steeper ($蠅^{-3.36}$) than the other transient accreting sources. We find significantly high noise strength estimates above the super-Eddington luminosity levels, which may arise from the torque fluctuations due to interactions with the quadrupole fields at such levels. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11937v2-abstract-full').style.display = 'none'; document.getElementById('2304.11937v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 6 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.08816">arXiv:2304.08816</a> <span> [<a href="https://arxiv.org/pdf/2304.08816">pdf</a>, <a href="https://arxiv.org/format/2304.08816">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202346284">10.1051/0004-6361/202346284 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray flashes from the low-mass X-ray binary IGR J17407-2808 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">C. Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">E. Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Berton%2C+M">M. Berton</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Congiu%2C+E">E. Congiu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.08816v1-abstract-short" style="display: inline;"> IGR J17407-2808 is an enigmatic and poorly studied X-ray binary that was recently observed quasi-simultaneously with NuSTAR and XMM-Newton. In this paper we report the results of this observational campaign. During the first 60 ks of observation, the source was caught in a relatively low emission state, characterised by a modest variability and an average flux of ~8.3E-13 erg/cm^2/s (4-60 keV). Af… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.08816v1-abstract-full').style.display = 'inline'; document.getElementById('2304.08816v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.08816v1-abstract-full" style="display: none;"> IGR J17407-2808 is an enigmatic and poorly studied X-ray binary that was recently observed quasi-simultaneously with NuSTAR and XMM-Newton. In this paper we report the results of this observational campaign. During the first 60 ks of observation, the source was caught in a relatively low emission state, characterised by a modest variability and an average flux of ~8.3E-13 erg/cm^2/s (4-60 keV). Afterwards, IGR J17407-2808 entered a significantly more active emission state that persisted for the remaining ~40 ks of the NuSTAR observation. During this state, IGR J17407-2808 displayed several fast X-ray flares, featuring durations of ~1-100 s and profiles with either single or multiple peaks. The source flux in the flaring state reached values as high as 2E-9 erg/cm^2/s (4-60 keV), leading to a measured dynamic range during the NuSTAR and XMM-Newton campaign of >~ 10^3. We also analysed available archival photometric near-infrared data of IGR J17407-2808 to improve the constraints available so far on the the nature of the donor star hosted in this system. Our analysis shows that the donor star can be either a rare K or M-type sub-subgiant or an K type main sequence star, or sub-giant star. Our findings support the classification of IGR J17407-2808 as a low-mass X-ray binary. We discuss the source X-ray behaviour as recorded by NuSTAR and XMM-Newton in view of this revised classification. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.08816v1-abstract-full').style.display = 'none'; document.getElementById('2304.08816v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 674, A100 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.00925">arXiv:2304.00925</a> <span> [<a href="https://arxiv.org/pdf/2304.00925">pdf</a>, <a href="https://arxiv.org/format/2304.00925">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202346581">10.1051/0004-6361/202346581 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A polarimetrically oriented X-ray stare at the accreting pulsar EXO 2030+375 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Tsygankov%2C+S+S">Sergey S. Tsygankov</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Forsblom%2C+S+V">Sofia V. Forsblom</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Du%2C+Y">Yujia Du</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Lutovinov%2C+A+A">Alexander A. Lutovinov</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Mereminskiy%2C+I+A">Ilya A. Mereminskiy</a>, <a href="/search/astro-ph?searchtype=author&query=Molkov%2C+S+V">Sergey V. Molkov</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">Pierre-Olivier Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Shtykovsky%2C+A+E">Andrey E. Shtykovsky</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Baumgartner%2C+W+H">Wayne H. Baumgartner</a> , et al. (82 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.00925v2-abstract-short" style="display: inline;"> Accreting X-ray pulsars (XRPs) are presumably ideal targets for polarization measurements, as their high magnetic field strength is expected to polarize the emission up to a polarization degree of ~80%. However, such expectations are being challenged by recent observations of XRPs with the Imaging X-ray Polarimeter Explorer (IXPE). Here we report on the results of yet another XRP, EXO 2030+375, ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.00925v2-abstract-full').style.display = 'inline'; document.getElementById('2304.00925v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.00925v2-abstract-full" style="display: none;"> Accreting X-ray pulsars (XRPs) are presumably ideal targets for polarization measurements, as their high magnetic field strength is expected to polarize the emission up to a polarization degree of ~80%. However, such expectations are being challenged by recent observations of XRPs with the Imaging X-ray Polarimeter Explorer (IXPE). Here we report on the results of yet another XRP, EXO 2030+375, observed with IXPE and contemporarily monitored with Insight-HXMT and SRG/ART-XC. In line with recent results obtained with IXPE for similar sources, analysis of the EXO 2030+375 data returns a low polarization degree of 0%-3% in the phase-averaged study and variation in the range 2%-7% in the phase-resolved study. Using the rotating vector model we constrain the geometry of the system and obtain a value for the magnetic obliquity of ~$60^{\circ}$. Considering also the estimated pulsar inclination of ~$130^{\circ}$, this indicates that the magnetic axis swings close to the observer line of sight. Our joint polarimetric, spectral and timing analysis hint to a complex accreting geometry where magnetic multipoles with asymmetric topology and gravitational light bending significantly affect the observed source behavior. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.00925v2-abstract-full').style.display = 'none'; document.getElementById('2304.00925v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">A&A accepted. Proofs version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.01804">arXiv:2302.01804</a> <span> [<a href="https://arxiv.org/pdf/2302.01804">pdf</a>, <a href="https://arxiv.org/format/2302.01804">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202245807">10.1051/0004-6361/202245807 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> SRG/eROSITA-triggered XMM-Newton observations of three Be/X-ray binaries in the LMC: Discovery of X-ray pulsations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Haberl%2C+F">F. Haberl</a>, <a href="/search/astro-ph?searchtype=author&query=Maitra%2C+C">C. Maitra</a>, <a href="/search/astro-ph?searchtype=author&query=Kaltenbrunner%2C+D">D. Kaltenbrunner</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Monageng%2C+I+M">I. M. Monageng</a>, <a href="/search/astro-ph?searchtype=author&query=Udalski%2C+A">A. Udalski</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Kreykenbohm%2C+I">I. Kreykenbohm</a>, <a href="/search/astro-ph?searchtype=author&query=Maggi%2C+P">P. Maggi</a>, <a href="/search/astro-ph?searchtype=author&query=Rau%2C+A">A. Rau</a>, <a href="/search/astro-ph?searchtype=author&query=Vasilopoulos%2C+G">G. Vasilopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Weber%2C+P">P. Weber</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J. Wilms</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.01804v1-abstract-short" style="display: inline;"> Using data from eROSITA, the soft X-ray instrument aboard Spectrum-Roentgen-Gamma (SRG), we report the discovery of two new hard transients, eRASSU J050810.4-660653 and eRASSt J044811.1-691318, in the Large Magellanic Cloud. We also report the detection of the Be/X-ray binary RX J0501.6-7034 in a bright state. We initiated follow-up observations to investigate the nature of the new transients and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.01804v1-abstract-full').style.display = 'inline'; document.getElementById('2302.01804v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.01804v1-abstract-full" style="display: none;"> Using data from eROSITA, the soft X-ray instrument aboard Spectrum-Roentgen-Gamma (SRG), we report the discovery of two new hard transients, eRASSU J050810.4-660653 and eRASSt J044811.1-691318, in the Large Magellanic Cloud. We also report the detection of the Be/X-ray binary RX J0501.6-7034 in a bright state. We initiated follow-up observations to investigate the nature of the new transients and to search for X-ray pulsations coming from RX J0501.6-7034. We analysed the X-ray spectra and light curves from our XMM-Newton observations, obtained optical spectra using the South African Large Telescope to look for Balmer emission lines and utilised the archival data from the Optical Gravitational Lensing Experiment (OGLE) for the long-term monitoring of the optical counterparts. We find X-ray pulsations for eRASSU J050810.4-660653, RX J0501.6-7034, and eRASSt J044811.1-691318 of 40.6 s, 17.3 s, and 784 s, respectively. The Halpha emission lines with equivalent widths of -10.4 A (eRASSU J050810.4-660653) and -43.9 A (eRASSt J044811.1-691318) were measured, characteristic for a circumstellar disc around Be stars. The OGLE I- and V-band light curves of all three systems exhibit strong variability. A regular pattern of deep dips in the light curves of RX J0501.6-7034 suggests an orbital period of ~451 days. We identify the two new hard eROSITA transients eRASSU J050810.4-660653 and eRASSt J044811.1-691318 and the known Be/X-ray binary RX J0501.6-7034 as Be/X-ray binary pulsars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.01804v1-abstract-full').style.display = 'none'; document.getElementById('2302.01804v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 671, A90 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.05837">arXiv:2212.05837</a> <span> [<a href="https://arxiv.org/pdf/2212.05837">pdf</a>, <a href="https://arxiv.org/format/2212.05837">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stac3664">10.1093/mnras/stac3664 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The X-ray view of optically selected dual AGN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">Alessandra De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Vignali%2C+C">Cristian Vignali</a>, <a href="/search/astro-ph?searchtype=author&query=Severgnini%2C+P">Paola Severgnini</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanovi%C4%87%2C+T">Tamara Bogdanovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Charisi%2C+M">Maria Charisi</a>, <a href="/search/astro-ph?searchtype=author&query=Guainazzi%2C+M">Matteo Guainazzi</a>, <a href="/search/astro-ph?searchtype=author&query=Haiman%2C+Z">Zoltan Haiman</a>, <a href="/search/astro-ph?searchtype=author&query=Komossa%2C+S">S. Komossa</a>, <a href="/search/astro-ph?searchtype=author&query=Paragi%2C+Z">Zsolt Paragi</a>, <a href="/search/astro-ph?searchtype=author&query=Perez-Torres%2C+M">Miguel Perez-Torres</a>, <a href="/search/astro-ph?searchtype=author&query=Piconcelli%2C+E">Enrico Piconcelli</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Parvatikar%2C+M">Manali Parvatikar</a>, <a href="/search/astro-ph?searchtype=author&query=Serafinelli%2C+R">Roberto Serafinelli</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.05837v1-abstract-short" style="display: inline;"> We present a study of optically selected dual AGN with projected separations of 3--97~kpc. Using multi-wavelength (MWL) information (optical, X-rays, mid-IR), we characterized the intrinsic nuclear properties of this sample and compared them with those of isolated systems. Among the 124 X-ray detected AGN candidates, 52 appear in pairs and 72 as single X-ray sources. Through MWL analysis, we confi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.05837v1-abstract-full').style.display = 'inline'; document.getElementById('2212.05837v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.05837v1-abstract-full" style="display: none;"> We present a study of optically selected dual AGN with projected separations of 3--97~kpc. Using multi-wavelength (MWL) information (optical, X-rays, mid-IR), we characterized the intrinsic nuclear properties of this sample and compared them with those of isolated systems. Among the 124 X-ray detected AGN candidates, 52 appear in pairs and 72 as single X-ray sources. Through MWL analysis, we confirmed the presence of the AGN in a fraction >80\% of the detected targets in pairs (42 over 52). X-ray spectral analysis confirms the trend of increasing AGN luminosity with decreasing separation, suggesting that mergers may have contributed in triggering more luminous AGN. Through X/mid-IR ratio $vs$ X-ray colors, we estimated a fraction of Compton-thin AGN (with 10$^{22}$ cm$^{-2}$ $<$ N$_{\rm H} <$10$^{24}$ cm$^{-2}$) of about 80\%, while about 16\% are Compton thick (CT, with N$_{\rm H}>$10$^{24}$ cm$^{-2}$) sources. These fractions of obscured sources are larger than those found in samples of isolated AGN, confirming that pairs of AGN show higher obscuration. This trend is further confirmed by comparing the de-reddened [O\ III] emission with the observed X-ray luminosity. However, the derived fraction of Compton-thick sources in this sample at early stage of merging is lower than reported for late-merging dual-AGN samples. Comparing N$_{\rm H}$ from X-rays with that derived from E(B-V) from Narrow Line Regions, we find that the absorbing material is likely associated with the torus or the Broad Line Regions. We also explored the X-ray detection efficiency of dual-AGN candidates, finding that, when observed properly (at on-axis positions and with long exposures), X-ray data represent a powerful way to confirm and investigate dual-AGN systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.05837v1-abstract-full').style.display = 'none'; document.getElementById('2212.05837v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 4 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.06698">arXiv:2211.06698</a> <span> [<a href="https://arxiv.org/pdf/2211.06698">pdf</a>, <a href="https://arxiv.org/format/2211.06698">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202245015">10.1051/0004-6361/202245015 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> eRASSt J040515.6-745202, an X-ray burster in the Magellanic Bridge </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Haberl%2C+F">F. Haberl</a>, <a href="/search/astro-ph?searchtype=author&query=Vasilopoulos%2C+G">G. Vasilopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Maitra%2C+C">C. Maitra</a>, <a href="/search/astro-ph?searchtype=author&query=Valdes%2C+F">F. Valdes</a>, <a href="/search/astro-ph?searchtype=author&query=Lang%2C+D">D. Lang</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Kreykenbohm%2C+I">I. Kreykenbohm</a>, <a href="/search/astro-ph?searchtype=author&query=Rau%2C+A">A. Rau</a>, <a href="/search/astro-ph?searchtype=author&query=Weber%2C+P">P. Weber</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J. Wilms</a>, <a href="/search/astro-ph?searchtype=author&query=Maggi%2C+P">P. Maggi</a>, <a href="/search/astro-ph?searchtype=author&query=Bailyn%2C+C+D">C. D. Bailyn</a>, <a href="/search/astro-ph?searchtype=author&query=Jaisawal%2C+G+K">G. K. Jaisawal</a>, <a href="/search/astro-ph?searchtype=author&query=Ray%2C+P+S">P. S. Ray</a>, <a href="/search/astro-ph?searchtype=author&query=Treiber%2C+H">H. Treiber</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.06698v1-abstract-short" style="display: inline;"> During the third all-sky survey (eRASS3), eROSITA, the soft X-ray instrument aboard Spectrum-Roentgen-Gamma, detected a new hard X-ray transient, eRASSt J040515.6-745202, in the direction of the Magellanic Bridge. We arranged follow-up observations and searched for archival data to reveal the nature of the transient. Using X-ray observations with XMM-Newton, NICER, and Swift, we investigated the t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06698v1-abstract-full').style.display = 'inline'; document.getElementById('2211.06698v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.06698v1-abstract-full" style="display: none;"> During the third all-sky survey (eRASS3), eROSITA, the soft X-ray instrument aboard Spectrum-Roentgen-Gamma, detected a new hard X-ray transient, eRASSt J040515.6-745202, in the direction of the Magellanic Bridge. We arranged follow-up observations and searched for archival data to reveal the nature of the transient. Using X-ray observations with XMM-Newton, NICER, and Swift, we investigated the temporal and spectral behaviour of the source for over about 10 days. The X-ray light curve obtained from the XMM-Newton observation with an 28 ks exposure revealed a type-I X-ray burst with a peak bolometric luminosity of at least 1.4e37 erg/s. The burst energetics are consistent with a location of the burster at the distance of the Magellanic Bridge. The relatively long exponential decay time of the burst of 70 s indicates that it ignited in a H-rich environment. The non-detection of the source during the other eROSITA surveys, twelve and six months before and six months after eRASS3, suggests that the burst was discovered during a moderate outburst which reached 2.6e36 erg/s in persistent emission. During the NICER observations, the source showed alternating flux states with the high level at a similar brightness as during the XMM-Newton observation. This behaviour is likely caused by dips as also seen during the last hour of the XMM-Newton observation. Evidence for a recurrence of the dips with a period of 21.8 hr suggests eRASSt J040515.6-745202 is a low-mass X-ray binary (LMXB) system with an accretion disk seen nearly edge on. We identify a multi-wavelength counterpart to the X-ray source in UVW1 and g, r, i, and z images obtained by the optical/UV monitor on XMM-Newton and the Dark Energy Camera at the Cerro Tololo Inter-American Observatory. (abbreviated) <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06698v1-abstract-full').style.display = 'none'; document.getElementById('2211.06698v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics. 10 pages, 13 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 669, A66 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.06367">arXiv:2211.06367</a> <span> [<a href="https://arxiv.org/pdf/2211.06367">pdf</a>, <a href="https://arxiv.org/format/2211.06367">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202245123">10.1051/0004-6361/202245123 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The unaltered pulsar: GRO J1750-27, a super-critical X-ray neutron star that does not blink an eye </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">C. Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Falanga%2C+M">M. Falanga</a>, <a href="/search/astro-ph?searchtype=author&query=Altamirano%2C+D">D. Altamirano</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">E. Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">S. Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Jaisawal%2C+G+K">G. K. Jaisawal</a>, <a href="/search/astro-ph?searchtype=author&query=Kretschmar%2C+P">P. Kretschmar</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">M. Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Pradhan%2C+P">P. Pradhan</a>, <a href="/search/astro-ph?searchtype=author&query=Rothschild%2C+R">R. Rothschild</a>, <a href="/search/astro-ph?searchtype=author&query=Sanna%2C+A">A. Sanna</a>, <a href="/search/astro-ph?searchtype=author&query=Thalhammer%2C+P">P. Thalhammer</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J. Wilms</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.06367v2-abstract-short" style="display: inline;"> When accreting X-ray pulsars (XRPs) undergo bright X-ray outbursts, their luminosity-dependent spectral and timing features can be analysed in detail. The XRP GRO J1750-27 recently underwent one of such episodes, during which it was observed with $NuSTAR$ and monitored with $NICER$. Such a data set is rarely available, as it samples the outburst over more than a month at a luminosity that is alway… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06367v2-abstract-full').style.display = 'inline'; document.getElementById('2211.06367v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.06367v2-abstract-full" style="display: none;"> When accreting X-ray pulsars (XRPs) undergo bright X-ray outbursts, their luminosity-dependent spectral and timing features can be analysed in detail. The XRP GRO J1750-27 recently underwent one of such episodes, during which it was observed with $NuSTAR$ and monitored with $NICER$. Such a data set is rarely available, as it samples the outburst over more than a month at a luminosity that is always exceeding ${\sim}5\times10^{37}\,$erg/s. This value is larger than the typical critical luminosity value, where a radiative shock is formed above the neutron star's surface. Our data analysis of the joint spectra returns a highly ($N_H\sim(5-8)\times10^{22}\,$cm$^{-2}$) absorbed spectrum showing a K$伪$ iron line, a soft blackbody component likely originating from the inner edge of the accretion disk, and confirms the discovery of one of the deepest cyclotron lines, at a centroid energy of ${\sim}44\,$keV corresponding to a magnetic field strength of $4.7\times10^{12}\,$G. This value is independently supported by the best-fit physical model for spectral formation in accreting XRPs which, in agreement with recent findings, favours a distance of $14$ kpc and also reflects a bulk-Comptonization dominated accretion flow. Contrary to theoretical expectations and observational evidence from other similar sources, the pulse profiles as observed by $NICER$ through the outburst raise, peak and decay remain remarkably steady. The $NICER$ spectrum, including the iron K$伪$ line best-fit parameters, also remain almost unchanged at all probed outburst stages, similar to the pulsed fraction behaviour. We argue that all these phenomena are linked and interpret them as resulting from a saturation effect of the accretion column's emission, which occurs in the high-luminosity regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06367v2-abstract-full').style.display = 'none'; document.getElementById('2211.06367v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted on A&A -- proof version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 669, A38 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.06200">arXiv:2211.06200</a> <span> [<a href="https://arxiv.org/pdf/2211.06200">pdf</a>, <a href="https://arxiv.org/format/2211.06200">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stad304">10.1093/mnras/stad304 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> New Constraints on Decaying Dark Matter from INTEGRAL/SPI </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fischer%2C+S">S. Fischer</a>, <a href="/search/astro-ph?searchtype=author&query=Malyshev%2C+D">D. Malyshev</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.06200v2-abstract-short" style="display: inline;"> Based on almost 20 years of data collected by the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) we present constraints on a decaying dark matter particle undergoing a decay into two bodies, at least one of which is a photon, manifesting itself via a narrow line-like spectral feature. Our ON-OFF type analysis of the Milky Way observations a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06200v2-abstract-full').style.display = 'inline'; document.getElementById('2211.06200v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.06200v2-abstract-full" style="display: none;"> Based on almost 20 years of data collected by the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) we present constraints on a decaying dark matter particle undergoing a decay into two bodies, at least one of which is a photon, manifesting itself via a narrow line-like spectral feature. Our ON-OFF type analysis of the Milky Way observations allowed us to constrain the lifetime to be $\gtrsim 10^{20}-10^{21}$ yrs for DM particles with masses $40\,\text{keV}\,<\,M_{\text{DM}}\,<\,14\,\text{MeV}$. Within this mass range our analysis also reveals 32 line-like features detected at $\geq 3蟽$ significance, 29 of which coincide with known instrumental and astrophysical lines. In particular, we report on the detection of the electron-positron annihilation (511 keV) and $^{26}$Al (1809 keV) lines with spatial profiles consistent with previous results in the literature. For the particular case of the sterile neutrino DM we report the limits on the mixing angle as a function of sterile neutrino mass. We discuss the dominant impact of systematic uncertainties connected to the strongly time-variable INTEGRAL/SPI instrumental background as well as the ones connected to the uncertainties of MW DM density profile measurements on the derived results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06200v2-abstract-full').style.display = 'none'; document.getElementById('2211.06200v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">To match accepted MNRAS version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.01664">arXiv:2209.01664</a> <span> [<a href="https://arxiv.org/pdf/2209.01664">pdf</a>, <a href="https://arxiv.org/format/2209.01664">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202244328">10.1051/0004-6361/202244328 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Broadband study and the discovery of pulsations from the Be/X-ray binary eRASSU J052914.9-662446 in the Large Magellanic Cloud </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Maitra%2C+C">C. Maitra</a>, <a href="/search/astro-ph?searchtype=author&query=Kaltenbrunner%2C+D">D. Kaltenbrunner</a>, <a href="/search/astro-ph?searchtype=author&query=Haberl%2C+F">F. Haberl</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Monageng%2C+I+M">I. M. Monageng</a>, <a href="/search/astro-ph?searchtype=author&query=Udalski%2C+A">A. Udalski</a>, <a href="/search/astro-ph?searchtype=author&query=Carpano%2C+S">S. Carpano</a>, <a href="/search/astro-ph?searchtype=author&query=Coley%2C+J+B">J. B. Coley</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">C. Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=K%C3%B6nig%2C+O">O. K枚nig</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Vasilopoulos%2C+G">G. Vasilopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J. Wilms</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.01664v1-abstract-short" style="display: inline;"> Context. The Magellanic Clouds are our nearest star-forming galaxies. While the population of high-mass X-ray binaries (HMXBs) in the Small Magellanic Cloud (SMC) is relatively well studied, our knowledge about the Large Magellanic Cloud (LMC) is far from complete given its large angular extent and insufficient coverage with X-ray observations. Aims. We conducted a search for new HMXBs in the LMC… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.01664v1-abstract-full').style.display = 'inline'; document.getElementById('2209.01664v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.01664v1-abstract-full" style="display: none;"> Context. The Magellanic Clouds are our nearest star-forming galaxies. While the population of high-mass X-ray binaries (HMXBs) in the Small Magellanic Cloud (SMC) is relatively well studied, our knowledge about the Large Magellanic Cloud (LMC) is far from complete given its large angular extent and insufficient coverage with X-ray observations. Aims. We conducted a search for new HMXBs in the LMC using data from eROSITA, the soft X-ray instrument on board the Spektrum-Roentgen-Gamma (SRG) satellite. Methods. After confirming the nature of eRASSU J052914.9-662446 as a hard X-ray source positionally coincident with an early type star, we followed it up with optical spectroscopic observations from South African Large Telescope (SALT) and a dedicated NuSTAR observation. Results. We study the broadband timing and spectral behaviour of the newly discovered HMXB eRASSU J052914.9-662446 through eROSITA, Swift and NuSTAR data in X-rays and the Optical Gravitational Lensing Experiment (OGLE) and SALT RSS data at optical wavelength. We report on detection of the spin period at 1412 s and suggest an orbital period of the system of ~151 days, and thereby establish eRASSU J052914.9-662446 as an accreting pulsar. Further, through optical spectroscopic observations and the existence of H alpha emission the source is identified as a Be X-ray binary pulsar in the LMC. We also investigate the variability of the source in the optical and X-ray regime over the last decades and provide estimates on the possible magnetic field strength of the neutron star. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.01664v1-abstract-full').style.display = 'none'; document.getElementById('2209.01664v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 13 figures, 3 tables, accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 669, A30 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.11525">arXiv:2208.11525</a> <span> [<a href="https://arxiv.org/pdf/2208.11525">pdf</a>, <a href="https://arxiv.org/format/2208.11525">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="General Relativity and Quantum Cosmology">gr-qc</span> </div> </div> <p class="title is-5 mathjax"> Studying radiation of a white dwarf star falling on a black hole </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Niko%C5%82ajuk%2C+M">Marek Niko艂ajuk</a>, <a href="/search/astro-ph?searchtype=author&query=Karpiuk%2C+T">Tomasz Karpiuk</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Brewczyk%2C+M">Miros艂aw Brewczyk</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.11525v3-abstract-short" style="display: inline;"> We investigate electromagnetic and gravitational radiation generated during a process of the tidal stripping of a white dwarf star circulating a black hole. We model a white dwarf star by a Bose-Fermi droplet and use the quantum hydrodynamic equations to simulate evolution of a black hole-white dwarf binary system. While going through the periastron, the white dwarf loses a small fraction of its m… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.11525v3-abstract-full').style.display = 'inline'; document.getElementById('2208.11525v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.11525v3-abstract-full" style="display: none;"> We investigate electromagnetic and gravitational radiation generated during a process of the tidal stripping of a white dwarf star circulating a black hole. We model a white dwarf star by a Bose-Fermi droplet and use the quantum hydrodynamic equations to simulate evolution of a black hole-white dwarf binary system. While going through the periastron, the white dwarf loses a small fraction of its mass. The mass falling onto a black hole is a source of powerful electromagnetic and gravitational radiation. Bursts of ultraluminous radiation are flared at each periastron passage. This resembles the recurrent flaring of X-ray sources discovered recently by Irwin {\it et al.}. Gravitational energy bursts occur mainly through emission at very low frequencies. The accretion disc, formed due to stripping of a white dwarf, starts at some point to contribute continuously to radiation of both electromagnetic and gravitational types. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.11525v3-abstract-full').style.display = 'none'; document.getElementById('2208.11525v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 4 figures. New scaling included</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.11376">arXiv:2201.11376</a> <span> [<a href="https://arxiv.org/pdf/2201.11376">pdf</a>, <a href="https://arxiv.org/format/2201.11376">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac524f">10.3847/1538-4357/ac524f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Accreting on the edge: a luminosity-dependent cyclotron line in the Be/X-ray Binary 2S 1553-542 accompanied by accretion regimes transition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Bhargava%2C+Y">Yash Bhargava</a>, <a href="/search/astro-ph?searchtype=author&query=Coley%2C+J+B">Joel B. Coley</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Pradhan%2C+P">Pragati Pradhan</a>, <a href="/search/astro-ph?searchtype=author&query=Ballhausen%2C+R">Ralf Ballhausen</a>, <a href="/search/astro-ph?searchtype=author&query=Fuerst%2C+F">Felix Fuerst</a>, <a href="/search/astro-ph?searchtype=author&query=Islam%2C+N">Nazma Islam</a>, <a href="/search/astro-ph?searchtype=author&query=Jaisawal%2C+G+K">Gaurava K. Jaisawal</a>, <a href="/search/astro-ph?searchtype=author&query=Jenke%2C+P">Peter Jenke</a>, <a href="/search/astro-ph?searchtype=author&query=Kretschmar%2C+P">Peter Kretschmar</a>, <a href="/search/astro-ph?searchtype=author&query=Kreykenbohm%2C+I">Ingo Kreykenbohm</a>, <a href="/search/astro-ph?searchtype=author&query=Pottschmidt%2C+K">Katja Pottschmidt</a>, <a href="/search/astro-ph?searchtype=author&query=Sokolova-Lapa%2C+E">Ekaterina Sokolova-Lapa</a>, <a href="/search/astro-ph?searchtype=author&query=Staubert%2C+R">Rudiger Staubert</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">Joern Wilms</a>, <a href="/search/astro-ph?searchtype=author&query=Wilson-Hodge%2C+C+A">Colleen A. Wilson-Hodge</a>, <a href="/search/astro-ph?searchtype=author&query=Wolff%2C+M+T">Michael T. Wolff</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.11376v2-abstract-short" style="display: inline;"> Accreting X-ray pulsars (XRPs) undergo luminous X-ray outbursts during which the luminosity-dependent spectral and timing features of the neutron star's emission can be analyzed in detail, thus shedding light on the accretion regime at work. We took advantage of a monitoring campaign performed with NuSTAR, Swift/XRT, AstroSat and NICER, to follow the Be/X-ray Binary 2S 1553-542 along one of its ra… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.11376v2-abstract-full').style.display = 'inline'; document.getElementById('2201.11376v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.11376v2-abstract-full" style="display: none;"> Accreting X-ray pulsars (XRPs) undergo luminous X-ray outbursts during which the luminosity-dependent spectral and timing features of the neutron star's emission can be analyzed in detail, thus shedding light on the accretion regime at work. We took advantage of a monitoring campaign performed with NuSTAR, Swift/XRT, AstroSat and NICER, to follow the Be/X-ray Binary 2S 1553-542 along one of its rare outbursts and trace its spectral and timing evolution. We report the discovery of a luminosity-dependent cyclotron line energy for the first time in this source. The pulse profiles and pulsed fraction also show variability along the outburst, consistently with the interpretation that the source transitions from the sub-critical to the super-critical accretion regime, separated by a critical luminosity of L$_{crit}\approx4\times10^{37}$ erg/s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.11376v2-abstract-full').style.display = 'none'; document.getElementById('2201.11376v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted on ApJ. 11 pages, 7 figures, 3 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.10026">arXiv:2201.10026</a> <span> [<a href="https://arxiv.org/pdf/2201.10026">pdf</a>, <a href="https://arxiv.org/format/2201.10026">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stac210">10.1093/mnras/stac210 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Mysterious Odd Radio Circle near the Large Magellanic Cloud -- An Intergalactic Supernova Remnant? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Filipovi%C4%87%2C+M+D">Miroslav D. Filipovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Payne%2C+J+L">J. L. Payne</a>, <a href="/search/astro-ph?searchtype=author&query=Alsaberi%2C+R+Z+E">R. Z. E. Alsaberi</a>, <a href="/search/astro-ph?searchtype=author&query=Norris%2C+R+P">R. P. Norris</a>, <a href="/search/astro-ph?searchtype=author&query=Macgregor%2C+P+J">P. J. Macgregor</a>, <a href="/search/astro-ph?searchtype=author&query=Rudnick%2C+L">L. Rudnick</a>, <a href="/search/astro-ph?searchtype=author&query=Koribalski%2C+B+S">B. S. Koribalski</a>, <a href="/search/astro-ph?searchtype=author&query=Leahy%2C+D">D. Leahy</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Kothes%2C+R">R. Kothes</a>, <a href="/search/astro-ph?searchtype=author&query=Andernach%2C+H">H. Andernach</a>, <a href="/search/astro-ph?searchtype=author&query=Barnes%2C+L">L. Barnes</a>, <a href="/search/astro-ph?searchtype=author&query=Boji%C4%8Di%C4%87%2C+I+S">I. S. Boji膷i膰</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzetto%2C+L+M">L. M. Bozzetto</a>, <a href="/search/astro-ph?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/astro-ph?searchtype=author&query=Collier%2C+J+D">J. D. Collier</a>, <a href="/search/astro-ph?searchtype=author&query=Crawford%2C+E+J">E. J. Crawford</a>, <a href="/search/astro-ph?searchtype=author&query=Crocker%2C+R+M">R. M. Crocker</a>, <a href="/search/astro-ph?searchtype=author&query=Dai%2C+S">S. Dai</a>, <a href="/search/astro-ph?searchtype=author&query=Galvin%2C+T+J">T. J. Galvin</a>, <a href="/search/astro-ph?searchtype=author&query=Haberl%2C+F">F. Haberl</a>, <a href="/search/astro-ph?searchtype=author&query=Heber%2C+U">U. Heber</a>, <a href="/search/astro-ph?searchtype=author&query=Hill%2C+T">T. Hill</a>, <a href="/search/astro-ph?searchtype=author&query=Hopkins%2C+A+M">A. M. Hopkins</a>, <a href="/search/astro-ph?searchtype=author&query=Hurley-Walker%2C+N">N. Hurley-Walker</a> , et al. (26 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.10026v1-abstract-short" style="display: inline;"> We report the discovery of J0624-6948, a low-surface brightness radio ring, lying between the Galactic Plane and the Large Magellanic Cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ~196 arcsec. This source has phenomenological similarities to Odd Radio Circles (ORCs). Significant differences to the known ORCs - a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.10026v1-abstract-full').style.display = 'inline'; document.getElementById('2201.10026v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.10026v1-abstract-full" style="display: none;"> We report the discovery of J0624-6948, a low-surface brightness radio ring, lying between the Galactic Plane and the Large Magellanic Cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ~196 arcsec. This source has phenomenological similarities to Odd Radio Circles (ORCs). Significant differences to the known ORCs - a flatter radio spectral index, the lack of a prominent central galaxy as a possible host, and larger apparent size - suggest that J0624-6948 may be a different type of object. We argue that the most plausible explanation for J0624-6948 is an intergalactic supernova remnant due to a star that resided in the LMC outskirts that had undergone a single-degenerate type Ia supernova, and we are seeing its remnant expand into a rarefied, intergalactic environment. We also examine if a massive star or a white dwarf binary ejected from either galaxy could be the supernova progenitor. Finally, we consider several other hypotheses for the nature of the object, including the jets of an active galactic nucleus (AGN) or the remnant of a nearby stellar super-flare. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.10026v1-abstract-full').style.display = 'none'; document.getElementById('2201.10026v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages accepted to MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.08517">arXiv:2112.08517</a> <span> [<a href="https://arxiv.org/pdf/2112.08517">pdf</a>, <a href="https://arxiv.org/ps/2112.08517">ps</a>, <a href="https://arxiv.org/format/2112.08517">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stab3688">10.1093/mnras/stab3688 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Accretion of a clumped wind from a red supergiant donor onto a magnetar is suggested by the analysis of the XMM-Newton and NuSTAR observations of the X-ray binary 3A 1954+319 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">E. Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">C. Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Oskinova%2C+L">L. Oskinova</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2112.08517v1-abstract-short" style="display: inline;"> 3A 1954+319 has been classified for a long time as a symbiotic X-ray binary, hosting a slowly rotating neutron star and an aged M red giant. Recently, this classification has been revised thanks to the discovery that the donor star is an M supergiant. This makes 3A 1954+319 a rare type of high mass X-ray binary consisting of a neutron star and a red supergiant donor. In this paper, we analyse two… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.08517v1-abstract-full').style.display = 'inline'; document.getElementById('2112.08517v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.08517v1-abstract-full" style="display: none;"> 3A 1954+319 has been classified for a long time as a symbiotic X-ray binary, hosting a slowly rotating neutron star and an aged M red giant. Recently, this classification has been revised thanks to the discovery that the donor star is an M supergiant. This makes 3A 1954+319 a rare type of high mass X-ray binary consisting of a neutron star and a red supergiant donor. In this paper, we analyse two archival and still unpublished XMM-Newton and NuSTAR observations of the source. We perform a detailed hardness ratio-resolved spectral analysis to search for spectral variability that could help investigating the structures of the inhomogeneous M supergiant wind from which the neutron star is accreting. We discuss our results in the context of wind-fed supergiant X-ray binaries and show that the newest findings on 3A 1954+319 reinforce the hypothesis that the neutron star in this system is endowed with a magnetar-like magnetic field strength ($\gtrsim10^{14}$ G). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.08517v1-abstract-full').style.display = 'none'; document.getElementById('2112.08517v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication on MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.14541">arXiv:2106.14541</a> <span> [<a href="https://arxiv.org/pdf/2106.14541">pdf</a>, <a href="https://arxiv.org/format/2106.14541">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202140867">10.1051/0004-6361/202140867 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> eROSITA detection of flares from the Be/X-ray binary A0538-66 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Mereghetti%2C+S">S. Mereghetti</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Carpano%2C+S">S. Carpano</a>, <a href="/search/astro-ph?searchtype=author&query=Covino%2C+S">S. Covino</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Haberl%2C+F">F. Haberl</a>, <a href="/search/astro-ph?searchtype=author&query=Maitra%2C+C">C. Maitra</a>, <a href="/search/astro-ph?searchtype=author&query=Kreykenbohm%2C+I">I. Kreykenbohm</a>, <a href="/search/astro-ph?searchtype=author&query=Udalski%2C+A">A. Udalski</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.14541v1-abstract-short" style="display: inline;"> In 2018, XMM-Newton observed the awakening in X-rays of the Be/X-ray binary (Be/XRB) A0538-66. It showed bright and fast flares close to periastron with properties that had never been observed in other Be/XRBs before. We report the results from the observations of A0538-66 collected during the first all-sky survey of eROSITA, an X-ray telescope (0.2-10 keV) on board the Spektrum-Roentgen-Gamma (SR… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14541v1-abstract-full').style.display = 'inline'; document.getElementById('2106.14541v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.14541v1-abstract-full" style="display: none;"> In 2018, XMM-Newton observed the awakening in X-rays of the Be/X-ray binary (Be/XRB) A0538-66. It showed bright and fast flares close to periastron with properties that had never been observed in other Be/XRBs before. We report the results from the observations of A0538-66 collected during the first all-sky survey of eROSITA, an X-ray telescope (0.2-10 keV) on board the Spektrum-Roentgen-Gamma (SRG) satellite. eROSITA caught two flares within one orbital cycle at orbital phases $蠁= 0.29$ and $蠁= 0.93$ (where $蠁=0$ corresponds to periastron), with peak luminosities of $\sim 2-4 \times 10^{36}$ erg/s (0.2-10 keV) and durations of $42 \leq 螖t_{\rm fl} \leq 5.7\times 10^4$ s. The flare observed at $蠁\approx 0.29$ shows that the neutron star can accrete considerably far from periastron, although it is expected to be outside of the circumstellar disk, thus providing important new information about the plasma environment surrounding the binary system. We also report the results from the photometric monitoring of A0538-66 carried out with the REM, OGLE, and MACHO telescopes from January 1993 until March 2020. We found that the two sharp peaks that characterize the orbital modulation in the optical occur asymmetrically in the orbit, relative to the position of the donor star. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14541v1-abstract-full').style.display = 'none'; document.getElementById('2106.14541v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">To appear on A&A, Special Issue: The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 661, A22 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.10100">arXiv:2012.10100</a> <span> [<a href="https://arxiv.org/pdf/2012.10100">pdf</a>, <a href="https://arxiv.org/ps/2012.10100">ps</a>, <a href="https://arxiv.org/format/2012.10100">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039468">10.1051/0004-6361/202039468 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fast flaring observed from XMMU J053108.3-690923 by eROSITA: a supergiant fast X-ray transient in the Large Magellanic Cloud </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Maitra%2C+C">C. Maitra</a>, <a href="/search/astro-ph?searchtype=author&query=Haberl%2C+F">F. Haberl</a>, <a href="/search/astro-ph?searchtype=author&query=Vasilopoulos%2C+G">G. Vasilopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Dennerl%2C+K">K. Dennerl</a>, <a href="/search/astro-ph?searchtype=author&query=Carpano%2C+S">S. Carpano</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.10100v1-abstract-short" style="display: inline;"> Supergiant fast X-ray transients (SFXTs) are a peculiar class of supergiant high-mass X-ray binary (HMXB) systems characterised by extreme variability in the X-ray domain. In current models, this is mainly attributed to the clumpy nature of the stellar wind coupled with gating mechanisms involving the spin and magnetic field of the neutron star. We studied the X-ray properties of the supergiant HM… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10100v1-abstract-full').style.display = 'inline'; document.getElementById('2012.10100v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.10100v1-abstract-full" style="display: none;"> Supergiant fast X-ray transients (SFXTs) are a peculiar class of supergiant high-mass X-ray binary (HMXB) systems characterised by extreme variability in the X-ray domain. In current models, this is mainly attributed to the clumpy nature of the stellar wind coupled with gating mechanisms involving the spin and magnetic field of the neutron star. We studied the X-ray properties of the supergiant HMXB XMMU J053108.3-690923 in the Large Magellanic Cloud to understand its nature. We performed a detailed temporal and spectral analysis of the eROSITA and XMM-Newton data of XMMU J053108.3-690923. We confirm the putative pulsations previously reported for the source with high confidence, certifying its nature as a neutron star in orbit with a supergiant companion. We identify the extremely variable nature of the source in the form of flares seen in the eROSITA light curves. The source flux exhibits a total dynamic range of more than three orders of magnitude, which confirms its nature as an SFXT, and is the first such direct evidence from a HMXB outside our Galaxy exhibiting a very high dynamic range in luminosity as well as a fast flaring behaviour. We detect changes in the hardness ratio during the flaring intervals where the hardness ratio reaches its minimum during the peak of the flare and increases steeply shortly afterwards. This is also supported by the results of the spectral analysis carried out at the peak and off-flare intervals. This scenario is consistent with the presence of dense structures in the supergiant wind of XMMU J053108.3-690923 where the clumpy medium becomes photoionised at the peak of the flare leading to a drop in the photo-electric absorption. Further, we provide an estimate of the clumpiness of the medium and the magnetic field of the neutron star assuming a spin equilibrium condition. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10100v1-abstract-full').style.display = 'none'; document.getElementById('2012.10100v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 10 figures, Accepted for publication in A&A on 05/11/2020</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.02556">arXiv:2012.02556</a> <span> [<a href="https://arxiv.org/pdf/2012.02556">pdf</a>, <a href="https://arxiv.org/ps/2012.02556">ps</a>, <a href="https://arxiv.org/format/2012.02556">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/staa3788">10.1093/mnras/staa3788 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray reprocessing in accreting pulsar GX 301-2 observed with Insight-HXMT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">V. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Orlandini%2C+M">M. Orlandini</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+J">J. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S+N">S. N. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Nabizadeh%2C+A">A. Nabizadeh</a>, <a href="/search/astro-ph?searchtype=author&query=Gavran%2C+D">D. Gavran</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">S. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M+Y">M. Y. Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+X+B">X. B. Li</a>, <a href="/search/astro-ph?searchtype=author&query=Tao%2C+L">L. Tao</a>, <a href="/search/astro-ph?searchtype=author&query=Bu%2C+Q+C">Q. C. Bu</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+J+L">J. L. Qu</a>, <a href="/search/astro-ph?searchtype=author&query=Lu%2C+F+J">F. J. Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Song%2C+L+M">L. M. Song</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+T+P">T. P. Li</a>, <a href="/search/astro-ph?searchtype=author&query=Xu%2C+Y+P">Y. P. Xu</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+X+L">X. L. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+C+Z">C. Z. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+C">C. Cai</a> , et al. (78 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.02556v1-abstract-short" style="display: inline;"> We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe Kalpha, Kbeta and Ni Kalpha lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.02556v1-abstract-full').style.display = 'inline'; document.getElementById('2012.02556v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.02556v1-abstract-full" style="display: none;"> We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe Kalpha, Kbeta and Ni Kalpha lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding accretion material. According to the ratio of iron lines Kalpha and Kbeta, we infer the accretion material is in a low ionisation state. We find an orbital-dependent local absorption column density, which has a large value and strong variability around the periastron. We explain its variability as a result of inhomogeneities of the accretion environment and/or instabilities of accretion processes. In addition, the variable local column density is correlated with the equivalent width of the iron Kalpha lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.02556v1-abstract-full').style.display = 'none'; document.getElementById('2012.02556v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 5 figures, 2 tables, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.00392">arXiv:2012.00392</a> <span> [<a href="https://arxiv.org/pdf/2012.00392">pdf</a>, <a href="https://arxiv.org/ps/2012.00392">ps</a>, <a href="https://arxiv.org/format/2012.00392">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/staa3761">10.1093/mnras/staa3761 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A semi-analytical treatment to wind accretion in neutron star supergiant high mass X-ray binaries: I. eccentric orbits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">E. Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Falanga%2C+M">M. Falanga</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.00392v1-abstract-short" style="display: inline;"> We present in this paper a first step toward a semi-analytical treatment of the accretion process in wind-fed neutron star supergiant X-ray binaries with eccentric orbits. We consider the case of a spherically symmetric wind for the supergiant star and a simplified model for the accretion onto the compact object. A self-consistent calculation of the photoionization of the stellar wind by the X-ray… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00392v1-abstract-full').style.display = 'inline'; document.getElementById('2012.00392v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.00392v1-abstract-full" style="display: none;"> We present in this paper a first step toward a semi-analytical treatment of the accretion process in wind-fed neutron star supergiant X-ray binaries with eccentric orbits. We consider the case of a spherically symmetric wind for the supergiant star and a simplified model for the accretion onto the compact object. A self-consistent calculation of the photoionization of the stellar wind by the X-rays from the accreting neutron star is included. This effect is convolved with the modulation of the mass accretion rate induced by the eccentric orbit to obtain the expected X-ray luminosity of a system along the orbit. As part of our results, we first show that the bi-modality of low and high X-ray luminosity solutions for supergiant X-ray binaries reported in previous papers is likely to result from the effect of the neutron star approaching first and then moving away from the companion (without coexisting simultaneously). We propose that episodes of strong wind photoionization can give rise to off-states of the sources. Our calculations are applied to the case of a few classical supergiant X-ray binary systems with known eccentricities (Vela X-1, 4U 1907+09, GX 301-2) and to the case of the only supergiant fast X-ray transient with a confirmed eccentric orbit, IGR J08408-4503. The results are compared with observational findings on these sources. We also discuss the next steps needed to expand the calculations toward a more comprehensive treatment in future publications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00392v1-abstract-full').style.display = 'none'; document.getElementById('2012.00392v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.03244">arXiv:2009.03244</a> <span> [<a href="https://arxiv.org/pdf/2009.03244">pdf</a>, <a href="https://arxiv.org/format/2009.03244">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.newar.2020.101546">10.1016/j.newar.2020.101546 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Advances in Understanding High-Mass X-ray Binaries with INTEGRAL and Future Directions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kretschmar%2C+P">Peter Kretschmar</a>, <a href="/search/astro-ph?searchtype=author&query=F%C3%BCrst%2C+F">Felix F眉rst</a>, <a href="/search/astro-ph?searchtype=author&query=Sidoli%2C+L">Lara Sidoli</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">Enrico Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Alfonso-Garz%C3%B3n%2C+J">Julia Alfonso-Garz贸n</a>, <a href="/search/astro-ph?searchtype=author&query=Bodaghee%2C+A">Arash Bodaghee</a>, <a href="/search/astro-ph?searchtype=author&query=Chaty%2C+S">Sylvain Chaty</a>, <a href="/search/astro-ph?searchtype=author&query=Chernyakova%2C+M">Masha Chernyakova</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">Carlo Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Manousakis%2C+A">Antonios Manousakis</a>, <a href="/search/astro-ph?searchtype=author&query=Negueruela%2C+I">Ignacio Negueruela</a>, <a href="/search/astro-ph?searchtype=author&query=Postnov%2C+K">Konstantin Postnov</a>, <a href="/search/astro-ph?searchtype=author&query=Paizis%2C+A">Adamantia Paizis</a>, <a href="/search/astro-ph?searchtype=author&query=Reig%2C+P">Pablo Reig</a>, <a href="/search/astro-ph?searchtype=author&query=Rodes-Roca%2C+J+J">Jos茅 Joaqu铆n Rodes-Roca</a>, <a href="/search/astro-ph?searchtype=author&query=Tsygankov%2C+S">Sergey Tsygankov</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+A+J">Antony J. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=K%C3%BChnel%2C+M+B+n">Matthias Bissinger n茅 K眉hnel</a>, <a href="/search/astro-ph?searchtype=author&query=Blay%2C+P">Pere Blay</a>, <a href="/search/astro-ph?searchtype=author&query=Caballero%2C+I">Isabel Caballero</a>, <a href="/search/astro-ph?searchtype=author&query=Coe%2C+M+J">Malcolm J. Coe</a>, <a href="/search/astro-ph?searchtype=author&query=Domingo%2C+A">Albert Domingo</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Falanga%2C+M">Maurizio Falanga</a> , et al. (26 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.03244v1-abstract-short" style="display: inline;"> High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.03244v1-abstract-full').style.display = 'inline'; document.getElementById('2009.03244v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.03244v1-abstract-full" style="display: none;"> High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands, ranging from the infrared to very high energies. In this review, we provide a broad but concise summary of the physical processes dominating the emission from high mass X-ray binaries across virtually the whole electromagnetic spectrum. These comprise the interaction of stellar winds with the high gravitational and magnetic fields of compact objects, the behaviour of matter under extreme magnetic and gravity conditions, and the perturbation of the massive star evolutionary processes by presence in a binary system. We highlight the role of the INTEGRAL mission in the discovery of many of the most interesting objects in the high mass X-ray binary class and its contribution in reviving the interest for these sources over the past two decades. We show how the INTEGRAL discoveries have not only contributed to significantly increase the number of high mass X-ray binaries known, thus advancing our understanding of the population as a whole, but also have opened new windows of investigation that stimulated the multi-wavelength approach nowadays common in most astrophysical research fields. We conclude the review by providing an overview of future facilities being planned from the X-ray to the very high energy domain that will hopefully help us in finding an answer to the many questions left open after more than 18 years of INTEGRAL scientific observations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.03244v1-abstract-full').style.display = 'none'; document.getElementById('2009.03244v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">61 pages, 22 figures, 1 table, will be published in New Astronomy Reviews</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.13434">arXiv:2008.13434</a> <span> [<a href="https://arxiv.org/pdf/2008.13434">pdf</a>, <a href="https://arxiv.org/format/2008.13434">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202038855">10.1051/0004-6361/202038855 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The cyclotron line energy in Her X-1: stable after the decay </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Staubert%2C+R">R. Staubert</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Fuerst%2C+F">F. Fuerst</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J. Wilms</a>, <a href="/search/astro-ph?searchtype=author&query=Rothschild%2C+R+E">R. E. Rothschild</a>, <a href="/search/astro-ph?searchtype=author&query=Pottschmidt%2C+K">K. Pottschmidt</a>, <a href="/search/astro-ph?searchtype=author&query=Brumback%2C+M">M. Brumback</a>, <a href="/search/astro-ph?searchtype=author&query=Harrison%2C+F">F. Harrison</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.13434v1-abstract-short" style="display: inline;"> We summarize the results of a dedicated effort between 2012 and 2019 to follow the evolution of the cyclotron line in Her~X-1 through repeated NuSTAR observations. The previously observed nearly 20-year long decay of the cyclotron line energy has ended around 2012: from there onward the pulse phase averaged flux corrected cyclotron line energy has remained stable and constant at an average value o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.13434v1-abstract-full').style.display = 'inline'; document.getElementById('2008.13434v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.13434v1-abstract-full" style="display: none;"> We summarize the results of a dedicated effort between 2012 and 2019 to follow the evolution of the cyclotron line in Her~X-1 through repeated NuSTAR observations. The previously observed nearly 20-year long decay of the cyclotron line energy has ended around 2012: from there onward the pulse phase averaged flux corrected cyclotron line energy has remained stable and constant at an average value of Ecyc= (37.44+/-0.07) keV (normalized to a flux level of 6.8 RXTE/ASM-cts/s). The flux dependence of Ecyc discovered in 2007 is now measured with high precision, giving a slope of (0.675+/-0.075) keV/(ASM-cts/s), corresponding to an increase of 6.5% of Ecyc for an increase in flux by a factor of two. We also find that all line parameters as well as the continuum parameters show a correlation with X-ray flux. While a correlation between Ecyc and X-ray flux (both positive and negative) is now known for several accreting binaries with various suggestions for the underlying physics, the phenomenon of a long-term decay has so far only been seen in Her~X-1 and Vela~X-1, with far less convincing explanations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.13434v1-abstract-full').style.display = 'none'; document.getElementById('2008.13434v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 17 figures, Astronomy and Astrophysics (in press)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 642, A196 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.10665">arXiv:2008.10665</a> <span> [<a href="https://arxiv.org/pdf/2008.10665">pdf</a>, <a href="https://arxiv.org/format/2008.10665">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.newar.2020.101547">10.1016/j.newar.2020.101547 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> INTEGRAL view on Cataclysmic Variables and Symbiotic Binaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lutovinov%2C+A">Alexander Lutovinov</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">Valery Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Luna%2C+G+J+M">Gerardo Juan Manuel Luna</a>, <a href="/search/astro-ph?searchtype=author&query=Sazonov%2C+S">Sergey Sazonov</a>, <a href="/search/astro-ph?searchtype=author&query=de+Martino%2C+D">Domitilla de Martino</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Falanga%2C+M">Maurizio Falanga</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.10665v1-abstract-short" style="display: inline;"> Accreting white dwarfs (WDs) constitute a significant fraction of the hard X-ray sources detected by the INTEGRAL observatory. Most of them are magnetic Cataclysmic Variables (CVs) of the intermediate polar (IP) and polar types, but the contribution of the Nova-likes systems and the systems with optically thin boundary layers, Dwarf Novae (DNs) and Symbiotic Binaries (or Symbiotic Stars, SySs) in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.10665v1-abstract-full').style.display = 'inline'; document.getElementById('2008.10665v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.10665v1-abstract-full" style="display: none;"> Accreting white dwarfs (WDs) constitute a significant fraction of the hard X-ray sources detected by the INTEGRAL observatory. Most of them are magnetic Cataclysmic Variables (CVs) of the intermediate polar (IP) and polar types, but the contribution of the Nova-likes systems and the systems with optically thin boundary layers, Dwarf Novae (DNs) and Symbiotic Binaries (or Symbiotic Stars, SySs) in quiescence is also not negligible. Here we present a short review of the results obtained from the observations of cataclysmic variables and symbiotic binaries by INTEGRAL. The highlight results include the significant increase of the known IP population, determination of the WD mass for a significant fraction of IPs, the establishment of the luminosity function of magnetic CVs, and uncovering origin of the Galactic ridge X-ray emission which appears to largely be associated with hard emission from magnetic CVs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.10665v1-abstract-full').style.display = 'none'; document.getElementById('2008.10665v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">55 pages, 8 figures, 2 tables, will be published in New Astronomy Reviews</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.11009">arXiv:2002.11009</a> <span> [<a href="https://arxiv.org/pdf/2002.11009">pdf</a>, <a href="https://arxiv.org/ps/2002.11009">ps</a>, <a href="https://arxiv.org/format/2002.11009">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201936479">10.1051/0004-6361/201936479 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An X-ray activity cycle on the young solar-like star $蔚\ \rm Eridani$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Coffaro%2C+M">M. Coffaro</a>, <a href="/search/astro-ph?searchtype=author&query=Stelzer%2C+B">B. Stelzer</a>, <a href="/search/astro-ph?searchtype=author&query=Orlando%2C+S">S. Orlando</a>, <a href="/search/astro-ph?searchtype=author&query=Hall%2C+J">J. Hall</a>, <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">T. S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=Wolter%2C+U">U. Wolter</a>, <a href="/search/astro-ph?searchtype=author&query=Mittag%2C+M">M. Mittag</a>, <a href="/search/astro-ph?searchtype=author&query=Sanz-Forcada%2C+J">J. Sanz-Forcada</a>, <a href="/search/astro-ph?searchtype=author&query=Schneider%2C+P+C">P. C. Schneider</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.11009v1-abstract-short" style="display: inline;"> In 2015 we started the XMM-Newton monitoring of the young solar-like star Epsilon Eridani (440 Myr), one of the youngest solar-like stars with a known chromospheric CaII cycle. By analyzing the most recent Mount Wilson S-index CaII data of this star, we found that the chromospheric cycle lasts 2.92 +/- 0.02 yr, in agreement with past results. From the long-term X-ray lightcurve, we find clear and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.11009v1-abstract-full').style.display = 'inline'; document.getElementById('2002.11009v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.11009v1-abstract-full" style="display: none;"> In 2015 we started the XMM-Newton monitoring of the young solar-like star Epsilon Eridani (440 Myr), one of the youngest solar-like stars with a known chromospheric CaII cycle. By analyzing the most recent Mount Wilson S-index CaII data of this star, we found that the chromospheric cycle lasts 2.92 +/- 0.02 yr, in agreement with past results. From the long-term X-ray lightcurve, we find clear and systematic X-ray variability of our target, consistent with the chromospheric CaII cycle. The average X-ray luminosity results to be 2 x 10^28 erg/s, with an amplitude that is only a factor 2 throughout the cycle. We apply a new method to describe the evolution of the coronal emission measure distribution of Epsilon Eridani in terms of solar magnetic structures: active regions, cores of active regions and flares covering the stellar surface at varying filling fractions. Combinations of these magnetic structures can describe the observed X-ray emission measure of Epsilon Eridani only if the solar flare emission measure distribution is restricted to events in the decay phase. The interpretation is that flares in the corona of Epsilon Eridani last longer than their solar counterparts. We ascribe this to the lower metallicity of Epsilon Eridani. Our analysis revealed also that the X-ray cycle of Epsilon Eridani is strongly dominated by cores of active regions. The coverage fraction of cores throughout the cycle changes by the same factor as the X-ray luminosity. The maxima of the cycle are characterized by a high percentage of covering fraction of the flares, consistent with the fact that flaring events are seen in the corresponding short-term X-ray lightcurves predominately at the cycle maxima. The high X-ray emission throughout the cycle of Epsilon Eridani is thus explained by the high percentage of magnetic structures on its surface. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.11009v1-abstract-full').style.display = 'none'; document.getElementById('2002.11009v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 27 figures, 2 tables. Accepted by Astronomy and Astrophysics. Abstract shortened for the arXiv listing</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 636, A49 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.08919">arXiv:2002.08919</a> <span> [<a href="https://arxiv.org/pdf/2002.08919">pdf</a>, <a href="https://arxiv.org/ps/2002.08919">ps</a>, <a href="https://arxiv.org/format/2002.08919">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/staa569">10.1093/mnras/staa569 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Switches between accretion structures during flares in 4U 1901+03 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">S. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">V. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Tsygankov%2C+S">S. Tsygankov</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Nabizadeh%2C+A">A. Nabizadeh</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S+N">S. N. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M+Y">M. Y. Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Tao%2C+L">L. Tao</a>, <a href="/search/astro-ph?searchtype=author&query=Bu%2C+Q+C">Q. C. Bu</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+J+L">J. L. Qu</a>, <a href="/search/astro-ph?searchtype=author&query=Lu%2C+F+J">F. J. Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Song%2C+L+M">L. M. Song</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+T+P">T. P. Li</a>, <a href="/search/astro-ph?searchtype=author&query=Xu%2C+Y+P">Y. P. Xu</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+X+L">X. L. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+C+Z">C. Z. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+C">C. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+Z">Z. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+G">G. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+T+X">T. X. Chen</a> , et al. (98 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.08919v1-abstract-short" style="display: inline;"> We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the flares, which have a duration from tens to hundreds… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.08919v1-abstract-full').style.display = 'inline'; document.getElementById('2002.08919v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.08919v1-abstract-full" style="display: none;"> We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the flares, which have a duration from tens to hundreds of seconds, are generally brighter than the persistent emission by a factor of $\sim$ 1.5. The pulse profile shape during the flares can be significantly different than that of the persistent emission. In particular, a phase shift is clearly observed in many cases. We interpret these findings as direct evidence of changes of the pulsed beam pattern, due to transitions between the sub- and super-critical accretion regimes on a short time scale. We also observe that at comparable luminosities the flares' pulse profiles are rather similar to those of the persistent emission. This indicates that the accretion on the polar cap of the neutron star is mainly determined by the luminosity, i.e., the mass accretion rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.08919v1-abstract-full').style.display = 'none'; document.getElementById('2002.08919v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 8 figures, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.03955">arXiv:1910.03955</a> <span> [<a href="https://arxiv.org/pdf/1910.03955">pdf</a>, <a href="https://arxiv.org/ps/1910.03955">ps</a>, <a href="https://arxiv.org/format/1910.03955">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stz2745">10.1093/mnras/stz2745 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Timing analysis of 2S 1417-624 observed with NICER and Insight-HXMT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">V. Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Gungor%2C+C">C. Gungor</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">S. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S+-">S. -N. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M+-">M. -Y. Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+L+J">L. J. Qu</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y+P">Y. P. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Bu%2C+Q+C">Q. C. Bu</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+X+L">X. L. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+Z">Z. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+G">G. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+T+X">T. X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y+B">Y. B. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W+W">W. W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Deng%2C+J+K">J. K. Deng</a>, <a href="/search/astro-ph?searchtype=author&query=Dong%2C+Y+W">Y. W. Dong</a>, <a href="/search/astro-ph?searchtype=author&query=Du%2C+Y+Y">Y. Y. Du</a>, <a href="/search/astro-ph?searchtype=author&query=Fu%2C+M+X">M. X. Fu</a>, <a href="/search/astro-ph?searchtype=author&query=Gao%2C+G+H">G. H. Gao</a> , et al. (91 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.03955v1-abstract-short" style="display: inline;"> We present a study of timing properties of the accreting pulsar 2S 1417-624 observed during its 2018 outburst, based on Swift/BAT, Fermi/GBM, Insight-HXMT and NICER observations. We report a dramatic change of the pulse profiles with luminosity. The morphology of the profile in the range 0.2-10.0keV switches from double to triple peaks at $\sim2.5$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$ a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03955v1-abstract-full').style.display = 'inline'; document.getElementById('1910.03955v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.03955v1-abstract-full" style="display: none;"> We present a study of timing properties of the accreting pulsar 2S 1417-624 observed during its 2018 outburst, based on Swift/BAT, Fermi/GBM, Insight-HXMT and NICER observations. We report a dramatic change of the pulse profiles with luminosity. The morphology of the profile in the range 0.2-10.0keV switches from double to triple peaks at $\sim2.5$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$ and from triple to quadruple peaks at $\sim7$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$. The profile at high energies (25-100keV) shows significant evolutions as well. We explain this phenomenon according to existing theoretical models. We argue that the first change is related to the transition from the sub to the super-critical accretion regime, while the second to the transition of the accretion disc from the gas-dominated to the radiation pressure-dominated state. Considering the spin-up as well due to the accretion torque, this interpretation allows to estimate the magnetic field self-consistently at $\sim7\times 10^{12}$G. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03955v1-abstract-full').style.display = 'none'; document.getElementById('1910.03955v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 4 figures, 1 tables, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.03321">arXiv:1910.03321</a> <span> [<a href="https://arxiv.org/pdf/1910.03321">pdf</a>, <a href="https://arxiv.org/format/1910.03321">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201936544">10.1051/0004-6361/201936544 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Accretion disc by Roche lobe overflow in the supergiant fast X-ray transient IGR J08408-4503 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.03321v1-abstract-short" style="display: inline;"> Supergiant fast X-ray transients (SFXTs) are X-ray binary systems with a supergiant companion and likely a neutron star, which show a fast ($\sim 10^3$ s) and high variability with a dynamic range up to $10^{5-6}$. Given their extreme properties, they are considered among the most valuable laboratories to test accretion models. Recently, the orbital parameters of a member of this class, IGR J08408… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03321v1-abstract-full').style.display = 'inline'; document.getElementById('1910.03321v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.03321v1-abstract-full" style="display: none;"> Supergiant fast X-ray transients (SFXTs) are X-ray binary systems with a supergiant companion and likely a neutron star, which show a fast ($\sim 10^3$ s) and high variability with a dynamic range up to $10^{5-6}$. Given their extreme properties, they are considered among the most valuable laboratories to test accretion models. Recently, the orbital parameters of a member of this class, IGR J08408-4503, were obtained from optical observations. We used this information, together with X-ray observations from previous publications and new results from X-ray and optical data collected by INTEGRAL and presented in this work, to study the accretion mechanisms at work in IGR J08408-4503. We found that the high eccentricity of the compact object orbit and the large size of the donor star imply Roche lobe overflow (RLO) around the periastron. It is also likely that a fraction of the outer layers of the photosphere of the donor star are lost from the Lagrangian point $L_2$ during the periastron passages. On the basis of these findings, we discuss the flaring variability of IGR J08408-4503 assuming the presence of an accretion disc. We point out that IGR J08408-4503 may not be the only SFXT with an accretion disc fueled by RLO. These findings open a new scenario for accretion mechanisms in SFXTs, since most of them have so far been based on the assumption of spherically symmetric accretion. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03321v1-abstract-full').style.display = 'none'; document.getElementById('1910.03321v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 631, A135 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.02393">arXiv:1910.02393</a> <span> [<a href="https://arxiv.org/pdf/1910.02393">pdf</a>, <a href="https://arxiv.org/ps/1910.02393">ps</a>, <a href="https://arxiv.org/format/1910.02393">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Constant cyclotron line energy in Hercules X-1 -- Joint Insight-HXMT and NuSTAR observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Xiao%2C+G+C">G. C. Xiao</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">L. Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Staubert%2C+R">R. Staubert</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M+Y">M. Y. Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">S. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S+N">S. N. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Liao%2C+J+Y">J. Y. Liao</a>, <a href="/search/astro-ph?searchtype=author&query=Guo%2C+C+C">C. C. Guo</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+X+B">X. B. Li</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+W">W. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+J+L">J. L. Qu</a>, <a href="/search/astro-ph?searchtype=author&query=Lu%2C+F+J">F. J. Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+T+P">T. P. Li</a>, <a href="/search/astro-ph?searchtype=author&query=Song%2C+L+M">L. M. Song</a>, <a href="/search/astro-ph?searchtype=author&query=Xu%2C+Y+P">Y. P. Xu</a>, <a href="/search/astro-ph?searchtype=author&query=Bu%2C+Q+C">Q. C. Bu</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+C">C. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+X+L">X. L. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+Z">Z. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+G">G. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+T+X">T. X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y+B">Y. B. Chen</a> , et al. (91 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.02393v1-abstract-short" style="display: inline;"> The long-term evolution of the centroid energy of the CRSF in Her X-1 is still a mystery. We report a new measurement from a campaign between {\sl Insight}-HXMT and {\sl NuSTAR} performed in February 2018. Generally, the two satellites show well consistent results of timing and spectral properties. The joint spectral analysis confirms that the previously observed long decay phase has ended, and th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.02393v1-abstract-full').style.display = 'inline'; document.getElementById('1910.02393v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.02393v1-abstract-full" style="display: none;"> The long-term evolution of the centroid energy of the CRSF in Her X-1 is still a mystery. We report a new measurement from a campaign between {\sl Insight}-HXMT and {\sl NuSTAR} performed in February 2018. Generally, the two satellites show well consistent results of timing and spectral properties. The joint spectral analysis confirms that the previously observed long decay phase has ended, and that the line energy instead keeps constant around 37.5 keV after flux correction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.02393v1-abstract-full').style.display = 'none'; document.getElementById('1910.02393v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.08078">arXiv:1907.08078</a> <span> [<a href="https://arxiv.org/pdf/1907.08078">pdf</a>, <a href="https://arxiv.org/format/1907.08078">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ab32f0">10.3847/2041-8213/ab32f0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Awakening of the fast-spinning accreting Be/X-ray pulsar A0538-66 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Mereghetti%2C+S">S. Mereghetti</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1907.08078v1-abstract-short" style="display: inline;"> A0538-66 is a Be/X-ray binary (Be/XRB) hosting a 69 ms pulsar. It emitted bright X-ray outbursts with peak luminosity up to $\sim 10^{39}$ erg/s during the first years after its discovery in 1977. Since then, it was always seen in quiescence or during outbursts with $L_x \lesssim 4 \times 10^{37}$ erg/s. In 2018 we carried out XMM-Newton observations of A0538-66 during three consecutive orbits whe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.08078v1-abstract-full').style.display = 'inline'; document.getElementById('1907.08078v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.08078v1-abstract-full" style="display: none;"> A0538-66 is a Be/X-ray binary (Be/XRB) hosting a 69 ms pulsar. It emitted bright X-ray outbursts with peak luminosity up to $\sim 10^{39}$ erg/s during the first years after its discovery in 1977. Since then, it was always seen in quiescence or during outbursts with $L_x \lesssim 4 \times 10^{37}$ erg/s. In 2018 we carried out XMM-Newton observations of A0538-66 during three consecutive orbits when the pulsar was close to periastron. In the first two observations we discovered a remarkable variability, with flares of typical durations between $\sim$2-50 s and peak luminosities up to $\sim 4\times 10^{38}$ erg/s (0.2-10 keV). Between the flares the luminosity was $\sim 2\times 10^{35}$ erg/s. The flares were absent in the third observation, during which A0538-66 had a steady luminosity of $2\times 10^{34}$ erg/s. In all observations, the X-ray spectra consist of a softer component, well described by an absorbed power law with photon index $螕_1\approx 2-4$ and $N_H\approx 10^{21}$ cm$^{-2}$, plus a harder power-law component ($螕_2\approx 0-0.5$) dominating above $\sim$2 keV. The softer component shows larger flux variations than the harder one, and a moderate hardening correlated with the luminosity. The fast flaring activity seen in these observations was never observed before in A0538-66, nor, to our best knowledge, in other Be/XRBs. We explore the possibility that during our observations the source was accreting in a regime of nearly spherically symmetric inflow. In this case, an atmosphere can form around the neutron star magnetosphere and the observed variability can be explained by transitions between the accretion and supersonic propeller regimes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.08078v1-abstract-full').style.display = 'none'; document.getElementById('1907.08078v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.13699">arXiv:1905.13699</a> <span> [<a href="https://arxiv.org/pdf/1905.13699">pdf</a>, <a href="https://arxiv.org/ps/1905.13699">ps</a>, <a href="https://arxiv.org/format/1905.13699">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201834983">10.1051/0004-6361/201834983 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Classification of low-luminosity stellar X-ray sources in the field of the Draco dwarf spheroidal galaxy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Saeedi%2C+S">Sara Saeedi</a>, <a href="/search/astro-ph?searchtype=author&query=Sasaki%2C+M">Manami Sasaki</a>, <a href="/search/astro-ph?searchtype=author&query=Stelzer%2C+B">Beate Stelzer</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1905.13699v2-abstract-short" style="display: inline;"> A previous study of the X-ray luminosity function of the X-ray sources in the field of the Draco dwarf spheroidal (dSph) galaxy indicated the presence of a population of unknown X-ray sources in the soft energy range of 0.5-2 keV. In 2015, Draco dSph was observed again in twenty-six deep XMM-Newton, observations providing an opportunity for a new study of the yet unclassified sources. We apply the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.13699v2-abstract-full').style.display = 'inline'; document.getElementById('1905.13699v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.13699v2-abstract-full" style="display: none;"> A previous study of the X-ray luminosity function of the X-ray sources in the field of the Draco dwarf spheroidal (dSph) galaxy indicated the presence of a population of unknown X-ray sources in the soft energy range of 0.5-2 keV. In 2015, Draco dSph was observed again in twenty-six deep XMM-Newton, observations providing an opportunity for a new study of the yet unclassified sources. We apply the classification criteria presented in our previous multi-wavelength study of the X-ray sources of the Draco dSph to the sources detected in the combined 2009 and 2015 XMM-Newton data set. These criteria are based on X-ray studies and properties of the optical, near-infrared, and mid-infrared counterparts and allows us to distinguish background active galactic nuclei~(AGNs) and galaxies from other types of X-ray sources. We present the classification of X-ray sources, for which the counterpart is identified as a stellar object based on our criteria from multi-wavelength data. We identify three new symbiotic stars in the Draco dSph with X-ray luminosities between $\sim$3.5$\times10^{34}$ erg s$^{-1}$ and 5.5$\times10^{34}$ erg s$^{-1}$. The X-ray spectral analysis shows that two of the classified symbiotic stars are $尾$-type. This is the first identification of this class of symbiotic stars in a nearby galaxy. Eight sources are classified as Galactic M dwarfs in the field of the Draco dSph. The distances of these M dwarfs are between$\sim$140-800 pc, their X-ray luminosities are between $10^{28}-10^{29}$ erg s$^{-1}$ and the logarithmic ratio of X-ray to bolometric luminosity, log$(\frac{L_\text{X}}{L_\text{bol}})$, is between $-3.4$ to $-2.1$. The multiple observations allowed us to investigate flare activity of the M dwarfs. Moreover, we classified three foreground sources, located at distances of the order of $\sim$1-3 kpc in the field of the Draco dSph. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.13699v2-abstract-full').style.display = 'none'; document.getElementById('1905.13699v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted, A&A, 05/2019, 19 pages, 45 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> AA/2018/34983 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 627, A128 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1903.02918">arXiv:1903.02918</a> <span> [<a href="https://arxiv.org/pdf/1903.02918">pdf</a>, <a href="https://arxiv.org/ps/1903.02918">ps</a>, <a href="https://arxiv.org/format/1903.02918">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201834390">10.1051/0004-6361/201834390 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring the role of X-ray reprocessing and irradiation in the anomalous bright optical outbursts of A0538-66 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">L. Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Mereghetti%2C+S">S. Mereghetti</a>, <a href="/search/astro-ph?searchtype=author&query=Hryniewicz%2C+K">K. Hryniewicz</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">A. Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1903.02918v1-abstract-short" style="display: inline;"> In 1981, the Be/X-ray binary (Be/XRB) A0538-66 showed outbursts characterized by high peak luminosities in the X-ray and optical bands. The optical outbursts were qualitatively explained as X-ray reprocessing in a gas cloud surrounding the binary system. Since then, further important information about A0538-66 have been obtained, and sophisticated photoionization codes have been developed to calcu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.02918v1-abstract-full').style.display = 'inline'; document.getElementById('1903.02918v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1903.02918v1-abstract-full" style="display: none;"> In 1981, the Be/X-ray binary (Be/XRB) A0538-66 showed outbursts characterized by high peak luminosities in the X-ray and optical bands. The optical outbursts were qualitatively explained as X-ray reprocessing in a gas cloud surrounding the binary system. Since then, further important information about A0538-66 have been obtained, and sophisticated photoionization codes have been developed to calculate the radiation emerging from a gas nebula illuminated by a central X-ray source. In the light of the new information and tools available, we studied again the enhanced optical emission displayed by A0538-66 to understand the mechanisms responsible for these unique events among the class of Be/XRBs. We performed about 10^5 simulations of a gas envelope photoionized by an X-ray source. We assumed for the shape of the gas cloud either a sphere or a circumstellar disc observed edge-on. We studied the effects of varying the main properties of the envelope and the influence of different input X-ray spectra on the optical/UV emission emerging from the photoionized cloud. We compared the computed spectra with the IUE spectrum and photometric UBV measurements obtained during the outburst of 29 April 1981. We also explored the role played by the X-ray heating of the surface of the donor star irradiated by the X-ray emission of the neutron star (NS). We found that reprocessing in a spherical cloud with a shallow radial density distribution can reproduce the optical/UV emission. To our knowledge, this configuration has never been observed either in A0538-66 during other epochs or in other Be/XRBs. We found, contrary to the case of most other Be/XRBs, that the optical/UV radiation produced by the X-ray heating of the surface of the donor star irradiated by the NS is non-negligible, due to the particular orbital parameters of this system that bring the NS very close to its companion. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.02918v1-abstract-full').style.display = 'none'; document.getElementById('1903.02918v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 March, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics. Abstract abridged to meet arXiv requirements</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 624, A9 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.07269">arXiv:1901.07269</a> <span> [<a href="https://arxiv.org/pdf/1901.07269">pdf</a>, <a href="https://arxiv.org/ps/1901.07269">ps</a>, <a href="https://arxiv.org/format/1901.07269">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stz264">10.1093/mnras/stz264 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Long-term evolutions of the cyclotron line energies in Her X-1, Vela X-1 and Cen X-3 as observed with Swift/BAT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">Long Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Staubert%2C+R">Ruediger Staubert</a>, <a href="/search/astro-ph?searchtype=author&query=Ducci%2C+L">Lorenzo Ducci</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shu Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+Z">Zhi Chang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1901.07269v1-abstract-short" style="display: inline;"> We study the long-term evolution of the centroid energy of cyclotron lines - often referered to as Cyclotron Resonance Scattering Features (CRSF) - in Her X-1, Vela X-1 and Cen X-3, using survey observations of the Burst Alert Telescope (BAT) onboard Swift. We find a significant decrease of the fundamental CRSF energy in Her X-1 and the first harmonic line energy in Vela X-1, since the launch of S… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.07269v1-abstract-full').style.display = 'inline'; document.getElementById('1901.07269v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.07269v1-abstract-full" style="display: none;"> We study the long-term evolution of the centroid energy of cyclotron lines - often referered to as Cyclotron Resonance Scattering Features (CRSF) - in Her X-1, Vela X-1 and Cen X-3, using survey observations of the Burst Alert Telescope (BAT) onboard Swift. We find a significant decrease of the fundamental CRSF energy in Her X-1 and the first harmonic line energy in Vela X-1, since the launch of Swift in 2004 and until 2010 and 2012, respectively.In both sources the decreases stopped at some time, with a quite stable centroid energy thereafter. Unlike in Her X-1 and Vela X-1, the CRSF energy in Cen X-3 does not show a long-term decrease. It is observed not to change for at least the past 14 years. The long-term variation of the line energy is a direct way to investigate the magnetic field structure in the polar regions of pulsars. Our results may stimulate the development of theoretical models, especially regarding to how the accreted mass accumulates in the accretion mound or how the magnetic field distorts around the polar cap. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.07269v1-abstract-full').style.display = 'none'; document.getElementById('1901.07269v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 January, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 5 figures, 3 tables, accepted for publication in MNRAS</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" 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