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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <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/2411.01215">arXiv:2411.01215</a> <span> [<a href="https://arxiv.org/pdf/2411.01215">pdf</a>, <a href="https://arxiv.org/format/2411.01215">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"> Detection of two TeV gamma-ray outbursts from NGC 1275 by LHAASO </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+T+L">T. L. Chen</a> , et al. (254 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="2411.01215v2-abstract-short" style="display: inline;"> The Water Cherenkov Detector Array (WCDA) is one of the components of Large High Altitude Air Shower Observatory (LHAASO) and can monitor any sources over two-thirds of the sky for up to 7 hours per day with >98\% duty cycle. In this work, we report the detection of two outbursts of the Fanaroff-Riley I radio galaxy NGC 1275 that were detected by LHAASO-WCDA between November 2022 and January 2023… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.01215v2-abstract-full').style.display = 'inline'; document.getElementById('2411.01215v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.01215v2-abstract-full" style="display: none;"> The Water Cherenkov Detector Array (WCDA) is one of the components of Large High Altitude Air Shower Observatory (LHAASO) and can monitor any sources over two-thirds of the sky for up to 7 hours per day with >98\% duty cycle. In this work, we report the detection of two outbursts of the Fanaroff-Riley I radio galaxy NGC 1275 that were detected by LHAASO-WCDA between November 2022 and January 2023 with statistical significance of 5.2~$蟽$ and 8.3~$蟽$. The observed spectral energy distribution in the range from 500 GeV to 3 TeV is fitted by a power-law with a best-fit spectral index of $伪=-3.37\pm0.52$ and $-3.35\pm0.29$, respectively. The outburst flux above 0.5~TeV was ($4.55\pm 4.21)\times~10^{-11}~\rm cm^{-2}~s^{-1}$ and ($3.45\pm 1.78)\times~10^{-11}~\rm cm^{-2}~s^{-1}$, corresponding to 60\%, 45\% of Crab Nebula flux. Variation analysis reveals the variability time-scale of days at the TeV energy band. A simple test by one-zone synchrotron self-Compton model reproduces the data in the gamma-ray band well. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.01215v2-abstract-full').style.display = 'none'; document.getElementById('2411.01215v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 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">11 pages, 8 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/2410.04425">arXiv:2410.04425</a> <span> [<a href="https://arxiv.org/pdf/2410.04425">pdf</a>, <a href="https://arxiv.org/format/2410.04425">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"> LHAASO detection of very-high-energy gamma-ray emission surrounding PSR J0248+6021 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2410.04425v2-abstract-short" style="display: inline;"> We report the detection of an extended very-high-energy (VHE) gamma-ray source coincident with the location of middle-aged (62.4~\rm kyr) pulsar PSR J0248+6021, by using the LHAASO-WCDA data of live 796 days and LHAASO-KM2A data of live 1216 days. A significant excess of \gray induced showers is observed both by WCDA in energy bands of 1-25~\rm TeV and KM2A in energy bands of $>$ 25~\rm TeV with 7… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04425v2-abstract-full').style.display = 'inline'; document.getElementById('2410.04425v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.04425v2-abstract-full" style="display: none;"> We report the detection of an extended very-high-energy (VHE) gamma-ray source coincident with the location of middle-aged (62.4~\rm kyr) pulsar PSR J0248+6021, by using the LHAASO-WCDA data of live 796 days and LHAASO-KM2A data of live 1216 days. A significant excess of \gray induced showers is observed both by WCDA in energy bands of 1-25~\rm TeV and KM2A in energy bands of $>$ 25~\rm TeV with 7.3 $蟽$ and 13.5 $蟽$, respectively. The best-fit position derived through WCDA data is R.A. = 42.06$^\circ \pm$ 0.12$^\circ$ and Dec. = 60.24$^\circ \pm $ 0.13$^\circ$ with an extension of 0.69$^\circ\pm$0.15$^\circ$ and that of the KM2A data is R.A.= 42.29$^\circ \pm $ 0.13$^\circ$ and Dec. = 60.38$^\circ \pm$ 0.07$^\circ$ with an extension of 0.37$^\circ\pm$0.07$^\circ$. No clear extended multiwavelength counterpart of this LHAASO source has been found from the radio band to the GeV band. The most plausible explanation of the VHE \gray emission is the inverse Compton process of highly relativistic electrons and positrons injected by the pulsar. These electrons/positrons are hypothesized to be either confined within the pulsar wind nebula or to have already escaped into the interstellar medium, forming a pulsar halo. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04425v2-abstract-full').style.display = 'none'; document.getElementById('2410.04425v2-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 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">12 pages, 10 figures, Accepted by Sci. China-Phys. Mech. Astron</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.04818">arXiv:2409.04818</a> <span> [<a href="https://arxiv.org/pdf/2409.04818">pdf</a>, <a href="https://arxiv.org/ps/2409.04818">ps</a>, <a href="https://arxiv.org/format/2409.04818">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/ad6b0a">10.3847/1538-4357/ad6b0a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A precessing stellar disk model for superorbital modulations of the gamma-ray binary LS I+61$^{\circ}$ 303 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Takata%2C+J">J. Takata</a>, <a href="/search/astro-ph?searchtype=author&query=Yu%2C+Y+W">Y. W. Yu</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="2409.04818v1-abstract-short" style="display: inline;"> Gamma-ray binary LS I+61$^{\circ}$ 303 consists of a neutron star orbiting around a Be star with a period of $P_{\rm orb}\simeq26.5\ {\rm d}$. Apart from orbital modulations, the binary shows long-term flux variations with a superorbital period of $P_{\rm sup}\simeq4.6\ {\rm yrs}$ as seen in nearly all wavelengths. The origin of this superorbital modulation is still not well understood. Under the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.04818v1-abstract-full').style.display = 'inline'; document.getElementById('2409.04818v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.04818v1-abstract-full" style="display: none;"> Gamma-ray binary LS I+61$^{\circ}$ 303 consists of a neutron star orbiting around a Be star with a period of $P_{\rm orb}\simeq26.5\ {\rm d}$. Apart from orbital modulations, the binary shows long-term flux variations with a superorbital period of $P_{\rm sup}\simeq4.6\ {\rm yrs}$ as seen in nearly all wavelengths. The origin of this superorbital modulation is still not well understood. Under the pulsar wind-stellar outflow interaction scenario, we propose that the superorbital modulations of LS I+61$^{\circ}$ 303 could be caused by the precession of the Be disk. Assuming X-rays arise from synchrotron radiation of the intrabinary shock, we develop an analytical model to calculate expected flux modulations over the orbital and superorbital phases. The asymmetric two-peak profiles in orbital light curves and sinusoidal-like long-term modulations are reproduced under the precessing disk scenario. The observed orbital phase drifting of the X-ray peak and our fitting of long-term X-ray data indicate that the neutron star is likely orbiting around the star with a small eccentricity and periastron phase around $桅_{\rm p}\sim0.6$. We compare the Corbet diagrams of LS I+61$^{\circ}$ 303 with other Be/X-ray binaries and the linear correlation in the $P_{\rm sup}-P_{\rm orb}$ diagram suggests that the precession of the Be disk in LS I+61$^{\circ}$ 303 is induced by the tidal torque of its neutron star companion. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.04818v1-abstract-full').style.display = 'none'; document.getElementById('2409.04818v1-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, 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">16 pages, 6 figures, 2 tables, accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, 973:162 (11pp), 2024 October 1 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.08698">arXiv:2406.08698</a> <span> [<a href="https://arxiv.org/pdf/2406.08698">pdf</a>, <a href="https://arxiv.org/format/2406.08698">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> <p class="title is-5 mathjax"> Constraints on Ultra Heavy Dark Matter Properties from Dwarf Spheroidal Galaxies with LHAASO Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2406.08698v1-abstract-short" style="display: inline;"> In this work we try to search for signals generated by ultra-heavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible gamma-ray by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter which have low fluxes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08698v1-abstract-full').style.display = 'inline'; document.getElementById('2406.08698v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.08698v1-abstract-full" style="display: none;"> In this work we try to search for signals generated by ultra-heavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible gamma-ray by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter which have low fluxes of astrophysical $纬$-ray background while large amount of dark matter. By analyzing more than 700 days observational data at LHAASO, no significant dark matter signal from 1 TeV to 1 EeV is detected. Accordingly we derive the most stringent constraints on the ultra-heavy dark matter annihilation cross-section up to EeV. The constraints on the lifetime of dark matter in decay mode are also derived. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08698v1-abstract-full').style.display = 'none'; document.getElementById('2406.08698v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">17 pages, 12 figures, accepted by PRL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.11826">arXiv:2405.11826</a> <span> [<a href="https://arxiv.org/pdf/2405.11826">pdf</a>, <a href="https://arxiv.org/format/2405.11826">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> </div> <p class="title is-5 mathjax"> Data quality control system and long-term performance monitor of the LHAASO-KM2A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bian%2C+W">W. Bian</a>, <a href="/search/astro-ph?searchtype=author&query=Bukevich%2C+A+V">A. V. Bukevich</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+H+X">H. X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S">S. Chen</a> , et al. (263 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="2405.11826v3-abstract-short" style="display: inline;"> The KM2A is the largest sub-array of the Large High Altitude Air Shower Observatory (LHAASO). It consists of 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). The data recorded by the EDs and MDs are used to reconstruct primary information of cosmic ray and gamma-ray showers. This information is used for physical analysis in gamma-ray astronomy and cosmic ray physics. To… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11826v3-abstract-full').style.display = 'inline'; document.getElementById('2405.11826v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.11826v3-abstract-full" style="display: none;"> The KM2A is the largest sub-array of the Large High Altitude Air Shower Observatory (LHAASO). It consists of 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). The data recorded by the EDs and MDs are used to reconstruct primary information of cosmic ray and gamma-ray showers. This information is used for physical analysis in gamma-ray astronomy and cosmic ray physics. To ensure the reliability of the LHAASO-KM2A data, a three-level quality control system has been established. It is used to monitor the status of detector units, stability of reconstructed parameters and the performance of the array based on observations of the Crab Nebula and Moon shadow. This paper will introduce the control system and its application on the LHAASO-KM2A data collected from August 2021 to July 2023. During this period, the pointing and angular resolution of the array were stable. From the observations of the Moon shadow and Crab Nebula, the results achieved using the two methods are consistent with each other. According to the observation of the Crab Nebula at energies from 25 TeV to 100 TeV, the time averaged pointing errors are estimated to be $-0.003^{\circ} \pm 0.005^{\circ}$ and $0.001^{\circ} \pm 0.006^{\circ}$ in the R.A. and Dec directions, respectively. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11826v3-abstract-full').style.display = 'none'; document.getElementById('2405.11826v3-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">15 pages, 9 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/2405.07691">arXiv:2405.07691</a> <span> [<a href="https://arxiv.org/pdf/2405.07691">pdf</a>, <a href="https://arxiv.org/format/2405.07691">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/ad5e6d">10.3847/2041-8213/ad5e6d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of Very-high-energy Gamma-ray Emissions from the Low Luminosity AGN NGC 4278 by LHAASO </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2405.07691v1-abstract-short" style="display: inline;"> The first source catalog of Large High Altitude Air Shower Observatory reported the detection of a very-high-energy gamma ray source, 1LHAASO J1219+2915. In this paper a further detailed study of the spectral and temporal behavior of this point-like source have been carried. The best-fit position of the TeV source ($\rm{RA}=185.05^{\circ}\pm0.04^{\circ}$, $\rm{Dec}=29.25^{\circ}\pm0.03^{\circ}$) i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07691v1-abstract-full').style.display = 'inline'; document.getElementById('2405.07691v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.07691v1-abstract-full" style="display: none;"> The first source catalog of Large High Altitude Air Shower Observatory reported the detection of a very-high-energy gamma ray source, 1LHAASO J1219+2915. In this paper a further detailed study of the spectral and temporal behavior of this point-like source have been carried. The best-fit position of the TeV source ($\rm{RA}=185.05^{\circ}\pm0.04^{\circ}$, $\rm{Dec}=29.25^{\circ}\pm0.03^{\circ}$) is compatible with NGC 4278 within $\sim0.03$ degree. Variation analysis shows an indication of the variability at a few months level in the TeV band, which is consistent with low frequency observations. Based on these observations, we report the detection of TeV $纬$-ray emissions from this low-luminosity AGN NGC 4278. The observations by LHAASO-WCDA during active period has a significance level of 8.8\,$蟽$ with best-fit photon spectral index $\varGamma=2.56\pm0.14$ and a flux $f_{1-10\,\rm{TeV}}=(7.0\pm1.1_{\rm{sta}}\pm0.35_{\rm{syst}})\times10^{-13}\,\rm{photons\,cm^{-2}\,s^{-1}}$, or approximately $5\%$ of the Crab Nebula. The discovery of VHE from NGC 4278 indicates that the compact, weak radio jet can efficiently accelerate particles and emit TeV photons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07691v1-abstract-full').style.display = 'none'; document.getElementById('2405.07691v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">11 pages, 5 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/2404.04801">arXiv:2404.04801</a> <span> [<a href="https://arxiv.org/pdf/2404.04801">pdf</a>, <a href="https://arxiv.org/ps/2404.04801">ps</a>, <a href="https://arxiv.org/format/2404.04801">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</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/10.1007/s41605-024-00467-8">10.1007/s41605-024-00467-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> LHAASO-KM2A detector simulation using Geant4 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (254 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="2404.04801v1-abstract-short" style="display: inline;"> KM2A is one of the main sub-arrays of LHAASO, working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV. Detector simulation is the important foundation for estimating detector performance and data analysis. It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units (>6000) with… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.04801v1-abstract-full').style.display = 'inline'; document.getElementById('2404.04801v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.04801v1-abstract-full" style="display: none;"> KM2A is one of the main sub-arrays of LHAASO, working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV. Detector simulation is the important foundation for estimating detector performance and data analysis. It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units (>6000) with large altitude difference (30 m) and huge coverage (1.3 km^2). In this paper, the design of the KM2A simulation code G4KM2A based on Geant4 is introduced. The process of G4KM2A is optimized mainly in memory consumption to avoid memory overffow. Some simpliffcations are used to signiffcantly speed up the execution of G4KM2A. The running time is reduced by at least 30 times compared to full detector simulation. The particle distributions and the core/angle resolution comparison between simulation and experimental data of the full KM2A array are also presented, which show good agreement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.04801v1-abstract-full').style.display = 'none'; document.getElementById('2404.04801v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.10010">arXiv:2403.10010</a> <span> [<a href="https://arxiv.org/pdf/2403.10010">pdf</a>, <a href="https://arxiv.org/format/2403.10010">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/10.1103/PhysRevLett.132.131002">10.1103/PhysRevLett.132.131002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=The+LHAASO+Collaboration"> The LHAASO Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu%2C+A">A. Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a> , et al. (256 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="2403.10010v2-abstract-short" style="display: inline;"> We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.10010v2-abstract-full').style.display = 'inline'; document.getElementById('2403.10010v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.10010v2-abstract-full" style="display: none;"> We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at $3.67 \pm 0.05 \pm 0.15$ PeV. Below the knee, the spectral index is found to be -$2.7413 \pm 0.0004 \pm 0.0050$, while above the knee, it is -$3.128 \pm 0.005 \pm 0.027$, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -$0.1200 \pm 0.0003 \pm 0.0341$. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.10010v2-abstract-full').style.display = 'none'; document.getElementById('2403.10010v2-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> 26 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 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">8 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review Letters 132, 131002 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.17082">arXiv:2310.17082</a> <span> [<a href="https://arxiv.org/pdf/2310.17082">pdf</a>, <a href="https://arxiv.org/ps/2310.17082">ps</a>, <a href="https://arxiv.org/format/2310.17082">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"> Does or did the supernova remnant Cassiopeia A operate as a PeVatron? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2310.17082v1-abstract-short" style="display: inline;"> For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE;… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.17082v1-abstract-full').style.display = 'inline'; document.getElementById('2310.17082v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.17082v1-abstract-full" style="display: none;"> For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE; $E_纬\geq 100$~TeV) $纬$-rays. In this context, the historical SNR Cassiopeia A (Cas A) is considered one of the most promising target for UHE observations. This paper presents the observation of Cas A and its vicinity by the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE band, combined with the young age of Cas A, enabled us to derive stringent model-independent limits on the energy budget of UHE protons and nuclei accelerated by Cas A at any epoch after the explosion. The results challenge the prevailing paradigm that Cas A-type SNRs are major suppliers of PeV CRs in the Milky Way. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.17082v1-abstract-full').style.display = 'none'; document.getElementById('2310.17082v1-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 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">11 pages, 3 figures, Accepted by the 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/2310.08845">arXiv:2310.08845</a> <span> [<a href="https://arxiv.org/pdf/2310.08845">pdf</a>, <a href="https://arxiv.org/format/2310.08845">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/10.1126/sciadv.adj2778">10.1126/sciadv.adj2778 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Very high energy gamma-ray emission beyond 10 TeV from GRB 221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu%2C+A">A. Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2310.08845v2-abstract-short" style="display: inline;"> The highest energy gamma-rays from gamma-ray bursts (GRBs) have important implications for their radiation mechanism. Here we report for the first time the detection of gamma-rays up to 13 TeV from the brightest GRB 221009A by the Large High Altitude Air-shower Observatory (LHAASO). The LHAASO-KM2A detector registered more than 140 gamma-rays with energies above 3 TeV during 230$-$900s after the t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08845v2-abstract-full').style.display = 'inline'; document.getElementById('2310.08845v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.08845v2-abstract-full" style="display: none;"> The highest energy gamma-rays from gamma-ray bursts (GRBs) have important implications for their radiation mechanism. Here we report for the first time the detection of gamma-rays up to 13 TeV from the brightest GRB 221009A by the Large High Altitude Air-shower Observatory (LHAASO). The LHAASO-KM2A detector registered more than 140 gamma-rays with energies above 3 TeV during 230$-$900s after the trigger. The intrinsic energy spectrum of gamma-rays can be described by a power-law after correcting for extragalactic background light (EBL) absorption. Such a hard spectrum challenges the synchrotron self-Compton (SSC) scenario of relativistic electrons for the afterglow emission above several TeV. Observations of gamma-rays up to 13 TeV from a source with a measured redshift of z=0.151 hints more transparency in intergalactic space than previously expected. Alternatively, one may invoke new physics such as Lorentz Invariance Violation (LIV) or an axion origin of very high energy (VHE) signals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08845v2-abstract-full').style.display = 'none'; document.getElementById('2310.08845v2-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">49pages, 11figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Advances, 9, eadj2778 (2023) 15 November 2023 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.10477">arXiv:2308.10477</a> <span> [<a href="https://arxiv.org/pdf/2308.10477">pdf</a>, <a href="https://arxiv.org/ps/2308.10477">ps</a>, <a href="https://arxiv.org/format/2308.10477">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"> What absorbs the early TeV photons of GRB 221009A? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Shen%2C+J">Jun-Yi Shen</a>, <a href="/search/astro-ph?searchtype=author&query=Zou%2C+Y">Yuan-Chuan Zou</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Gao%2C+D">Duan-Yuan Gao</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="2308.10477v2-abstract-short" style="display: inline;"> The tera-electronvolt (TeV) light curve of gamma-ray burst (GRB) 221009A shows an unprecedentedly rapid rise at the beginning epoch. This phenomenon could be due to the strong absorption of photons and electrons within the emitting region. As the external shock expands outwards and the radius increases, the volume of matter also increases, leading to a gradual decrease in the optical depth for TeV… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.10477v2-abstract-full').style.display = 'inline'; document.getElementById('2308.10477v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.10477v2-abstract-full" style="display: none;"> The tera-electronvolt (TeV) light curve of gamma-ray burst (GRB) 221009A shows an unprecedentedly rapid rise at the beginning epoch. This phenomenon could be due to the strong absorption of photons and electrons within the emitting region. As the external shock expands outwards and the radius increases, the volume of matter also increases, leading to a gradual decrease in the optical depth for TeV photons. We explore several possibilities for the physical origin of this peculiar behavior. We calculate the optical depth for TeV photons due to annihilation with lower energy photons in the external shock and scattering by electrons produced via cascading of the TeV emission. Even under aggressive assumptions, we find the optical depths for these processes are orders of magnitude too small to explain the observed light curve. Other sources of absorbers, such as electrons in the ejecta or external shock, also do not yield sufficient optical depths. Therefore, the origin of the early peculiar TeV light curve remains uncertain. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.10477v2-abstract-full').style.display = 'none'; document.getElementById('2308.10477v2-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 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">4pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.17030">arXiv:2305.17030</a> <span> [<a href="https://arxiv.org/pdf/2305.17030">pdf</a>, <a href="https://arxiv.org/format/2305.17030">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/10.3847/1538-4365/acfd29">10.3847/1538-4365/acfd29 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The First LHAASO Catalog of Gamma-Ray Sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2305.17030v2-abstract-short" style="display: inline;"> We present the first catalog of very-high energy and ultra-high energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory (LHAASO). The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array (WCDA) from March 2021 to September 2022 and 933 days of data recorded by the Kilometer Squared Array (KM2A) from January 2020 to September 2022.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17030v2-abstract-full').style.display = 'inline'; document.getElementById('2305.17030v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.17030v2-abstract-full" style="display: none;"> We present the first catalog of very-high energy and ultra-high energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory (LHAASO). The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array (WCDA) from March 2021 to September 2022 and 933 days of data recorded by the Kilometer Squared Array (KM2A) from January 2020 to September 2022. This catalog represents the main result from the most sensitive large coverage gamma-ray survey of the sky above 1 TeV, covering declination from $-$20$^{\circ}$ to 80$^{\circ}$. In total, the catalog contains 90 sources with an extended size smaller than $2^\circ$ and a significance of detection at $> 5蟽$. Based on our source association criteria, 32 new TeV sources are proposed in this study. Among the 90 sources, 43 sources are detected with ultra-high energy ($E > 100$ TeV) emission at $> 4蟽$ significance level. We provide the position, extension, and spectral characteristics of all the sources in this catalog. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17030v2-abstract-full').style.display = 'none'; document.getElementById('2305.17030v2-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> 27 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">40 pages, 13 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal Supplement Series, 271 (2024) 25 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.05372">arXiv:2305.05372</a> <span> [<a href="https://arxiv.org/pdf/2305.05372">pdf</a>, <a href="https://arxiv.org/format/2305.05372">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/10.1103/PhysRevLett.131.151001">10.1103/PhysRevLett.131.151001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/astro-ph?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/astro-ph?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2305.05372v2-abstract-short" style="display: inline;"> The diffuse Galactic $纬$-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this work we report the measurements of diffuse $纬$-rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer ar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05372v2-abstract-full').style.display = 'inline'; document.getElementById('2305.05372v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.05372v2-abstract-full" style="display: none;"> The diffuse Galactic $纬$-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this work we report the measurements of diffuse $纬$-rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner ($15^{\circ}<l<125^{\circ}$, $|b|<5^{\circ}$) and outer ($125^{\circ}<l<235^{\circ}$, $|b|<5^{\circ}$) Galactic plane are detected with $29.1蟽$ and $12.7蟽$ significance, respectively. The outer Galactic plane diffuse emission is detected for the first time in the very- to ultra-high-energy domain ($E>10$~TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of $-2.99\pm0.04$, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of $\sim3$ than the prediction. A similar spectrum with an index of $-2.99\pm0.07$ is found in the outer Galaxy region, and the absolute flux for $10\lesssim E\lesssim60$ TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05372v2-abstract-full').style.display = 'none'; document.getElementById('2305.05372v2-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">12 pages, 8 figures, 5 tables; accepted for publication in Physical Review Letters; source mask file provided as ancillary file</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 131, 151001 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.00345">arXiv:2112.00345</a> <span> [<a href="https://arxiv.org/pdf/2112.00345">pdf</a>, <a href="https://arxiv.org/ps/2112.00345">ps</a>, <a href="https://arxiv.org/format/2112.00345">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/10.1051/0004-6361/202142258">10.1051/0004-6361/202142258 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modelling the correlated keV/TeV light curves of Be/gamma-ray binaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Takata%2C+J">J. Takata</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="2112.00345v1-abstract-short" style="display: inline;"> Be/$纬$-ray binaries comprise a confirmed or presumptive pulsar orbiting a Be star and emit luminous $纬$-rays. Non-thermal emissions are thought to arise from synchrotron radiation and inverse-Compton (IC) scattering in the shock where the pulsar wind is terminated by the stellar outflow. We study wind interactions and shock radiations from such systems and show that the bimodal structures observed… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.00345v1-abstract-full').style.display = 'inline'; document.getElementById('2112.00345v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.00345v1-abstract-full" style="display: none;"> Be/$纬$-ray binaries comprise a confirmed or presumptive pulsar orbiting a Be star and emit luminous $纬$-rays. Non-thermal emissions are thought to arise from synchrotron radiation and inverse-Compton (IC) scattering in the shock where the pulsar wind is terminated by the stellar outflow. We study wind interactions and shock radiations from such systems and show that the bimodal structures observed in keV/TeV light curves are caused by enhanced synchrotron radiation and IC scattering during disc passages. We use a simple radiation model to reproduce orbital modulations of keV X-ray and TeV $纬$-ray flux and compare with two confirmed pulsar/Be star binaries (i.e. PSR B1259-63/LS 2883 and PSR J2032+4127/MT91 213), and two candidates (i.e. HESS J0632+057 and LS I +61$^{\circ}$303). We find that the keV/TeV light curves of the former two binaries can be well explained by the inclined disc model, while modelling the modulated emissions of the latter two sources remains challenging with current orbital solutions. Therefore, we propose alternative orbital geometries for HESS J0632+057 and LS I +61$^{\circ}$303. We estimate the positions and inclination angles of Be discs by fitting correlated keV/TeV light curves. Our results could be beneficial for future measurements of orbital parameters and searches for radio pulsations from presumed pulsars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.00345v1-abstract-full').style.display = 'none'; document.getElementById('2112.00345v1-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, 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">14 pages, 10 figures, 4 tables. Accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 658, A153 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.10445">arXiv:2106.10445</a> <span> [<a href="https://arxiv.org/pdf/2106.10445">pdf</a>, <a href="https://arxiv.org/ps/2106.10445">ps</a>, <a href="https://arxiv.org/format/2106.10445">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/10.1051/0004-6361/202140951">10.1051/0004-6361/202140951 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Radio absorption in high-mass gamma-ray binaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Guo%2C+Y+D">Y. D. Guo</a>, <a href="/search/astro-ph?searchtype=author&query=Yu%2C+Y+W">Y. W. Yu</a>, <a href="/search/astro-ph?searchtype=author&query=Takata%2C+J">J. Takata</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="2106.10445v1-abstract-short" style="display: inline;"> High-mass gamma-ray binaries consist of a presumptive pulsar in orbit with a massive star. The intense outflows from the star can absorb radio emission from the pulsar, making the detection of pulsation difficult. In this work, we present the basic geometry and formulae that describe the absorption process of a pulsar in binary with an O/B star and apply our model to two typical and well-studied b… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.10445v1-abstract-full').style.display = 'inline'; document.getElementById('2106.10445v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.10445v1-abstract-full" style="display: none;"> High-mass gamma-ray binaries consist of a presumptive pulsar in orbit with a massive star. The intense outflows from the star can absorb radio emission from the pulsar, making the detection of pulsation difficult. In this work, we present the basic geometry and formulae that describe the absorption process of a pulsar in binary with an O/B star and apply our model to two typical and well-studied binaries: PSR~B1259-63/LS~2883 and LS 5039. We investigate the influences of the equatorial disc of LS 2883 with different orientations on the dispersion measure and free-free absorption of the radio pulsation from PSR B1259-63. The observed data are consistent with the disc inserted on the orbital plane with a relatively large inclination angle. For LS 5039, due to its tight orbit, it was believed that the strong wind absorption makes detecting radio emissions from the putative pulsar unlikely. However, considering the wind interaction and orbital motion, a bow shock cavity and a Coriolis shock would be formed, thereby allowing the pulsations to partially avoid stellar outflow absorption. We investigate the dependence of the radio optical depth on the observing frequencies, the orbital inclination angle, and the wind parameters. We suppose that the presumptive pulsar in LS 5039 is similar to PSR B1259-63 with pulsed emission extending to several tens of gigahertz. In that case, there could be a transparent window for radio pulsations when the pulsar is moving around the inferior conjunction. The following deep monitoring of LS 5039 and other systems by radio telescopes at high radio frequencies might reveal the nature of compact objects in the future. Alternatively, even a null detection could still provide further constraints on the properties of the putative pulsar and stellar outflows. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.10445v1-abstract-full').style.display = 'none'; document.getElementById('2106.10445v1-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 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">9 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 652, A39 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.07527">arXiv:1904.07527</a> <span> [<a href="https://arxiv.org/pdf/1904.07527">pdf</a>, <a href="https://arxiv.org/ps/1904.07527">ps</a>, <a href="https://arxiv.org/format/1904.07527">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/10.1051/0004-6361/201935166">10.1051/0004-6361/201935166 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modelling the multi-wavelength emissions from PSR B1259-63/LS 2883: the effects of the stellar disc on shock radiations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Takata%2C+J">J. Takata</a>, <a href="/search/astro-ph?searchtype=author&query=Yi%2C+S+X">S. X. Yi</a>, <a href="/search/astro-ph?searchtype=author&query=Yu%2C+Y+W">Y. W. Yu</a>, <a href="/search/astro-ph?searchtype=author&query=Cheng%2C+K+S">K. S. Cheng</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="1904.07527v2-abstract-short" style="display: inline;"> PSR B1259-63/LS 2883 is an elliptical pulsar/Be star binary and emits broadband emissions from radio to TeV $纬$-rays. The massive star possesses an equatorial disc, which is inclined with the orbital plane of the pulsar. The non-thermal emission from the system is believed to be produced by the pulsar wind shock and the double-peak profiles in the X-ray and TeV $纬$-ray light curves are related to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.07527v2-abstract-full').style.display = 'inline'; document.getElementById('1904.07527v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.07527v2-abstract-full" style="display: none;"> PSR B1259-63/LS 2883 is an elliptical pulsar/Be star binary and emits broadband emissions from radio to TeV $纬$-rays. The massive star possesses an equatorial disc, which is inclined with the orbital plane of the pulsar. The non-thermal emission from the system is believed to be produced by the pulsar wind shock and the double-peak profiles in the X-ray and TeV $纬$-ray light curves are related to the phases of the pulsar passing through the disc region of the star. In this paper, we investigate the interactions between the pulsar wind and stellar outflows, especially with the presence of the disc, and present a multi-wavelength modelling of the emission from this system. We show that the double-peak profiles of X-ray and TeV $纬$-ray light curves are caused by the enhancements of the magnetic field and the soft photons at the shock during the disc passages. As the pulsar is passing through the equatorial disc, the additional pressure of the disc pushes the shock surface closer to the pulsar, which causes the enhancement of magnetic field in the shock, and thus increases the synchrotron luminosity. The TeV $纬$-rays due to the inverse-Compton (IC) scattering of shocked electrons with seed photons from the star is expected to peak around periastron which is inconsistent with observations. However, the shock heating of the stellar disc could provide additional seed photons for IC scattering during the disc passages, and thus produces the double-peak profiles as observed in the TeV $纬$-ray light curve. Our model can possibly be examined and applied to other similar gamma-ray binaries, such as PSR J2032+4127/MT91 213, HESS J0632+057, and LS I+61$^{\circ}$303. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.07527v2-abstract-full').style.display = 'none'; document.getElementById('1904.07527v2-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 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">14 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 627, A87 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.08080">arXiv:1703.08080</a> <span> [<a href="https://arxiv.org/pdf/1703.08080">pdf</a>, <a href="https://arxiv.org/ps/1703.08080">ps</a>, <a href="https://arxiv.org/format/1703.08080">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/10.1088/1674-4527/21/8/189">10.1088/1674-4527/21/8/189 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modeling the High-energy Emission from the Gamma-ray Binary 1FGL J1018.6-5856 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C+W">C. W. Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Takata%2C+J">J. Takata</a>, <a href="/search/astro-ph?searchtype=author&query=Yu%2C+Y+W">Y. W. Yu</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="1703.08080v3-abstract-short" style="display: inline;"> 1FGL J1018.6-5856 is a high mass gamma-ray binary containing a compact object orbiting around a massive star with a period of 16.544 d. If the compact object is a pulsar, non-thermal emissions are likely produced by electrons accelerated at the termination shock, and may also originate from the magnetosphere and the un-shocked wind of the pulsar. In this paper, we investigate the non-thermal emiss… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.08080v3-abstract-full').style.display = 'inline'; document.getElementById('1703.08080v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.08080v3-abstract-full" style="display: none;"> 1FGL J1018.6-5856 is a high mass gamma-ray binary containing a compact object orbiting around a massive star with a period of 16.544 d. If the compact object is a pulsar, non-thermal emissions are likely produced by electrons accelerated at the termination shock, and may also originate from the magnetosphere and the un-shocked wind of the pulsar. In this paper, we investigate the non-thermal emissions from the wind and the shock with different viewing geometries and study the multi-wavelength emissions from 1FGL J1018.6-5856. We present the analysis results of the \textit{Fermi}/LAT using nearly 10 years of data. The phase-resolved spectra indicate that the GeV emissions comprise a rather steady component that does not vary with orbital motion and a modulated component that shows flux maximum around inferior conjunction. The keV/TeV light curves of 1FGL J1018.6-5856 also exhibit a sharp peak around inferior conjunction, which are attributed to the boosted emission from the shock, while the broad sinusoidal modulations could be originating from the deflected shock tail at a larger distance. The modulations of GeV flux are likely caused by the boosted synchrotron emission from the shock and the IC emission from the un-shocked pulsar wind, while the steady component comes from the outer gap of the pulsar magnetosphere. Finally, we discuss the similarities and differences of 1FGL J1018.6-5856 with other binaries, like LS 5039. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.08080v3-abstract-full').style.display = 'none'; document.getElementById('1703.08080v3-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </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, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> RAA 2021 Vol. 21 No. 8, 189 </p> </li> </ol> <div 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