Search | arXiv e-print repository

<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"/> <meta name="viewport" content="width=device-width, initial-scale=1"/>  <link rel="apple-touch-icon" sizes="180x180" href="https://static.arxiv.org/static/base/1.0.0a5/images/icons/apple-touch-icon.png"> <link rel="icon" type="image/png" sizes="32x32" href="https://static.arxiv.org/static/base/1.0.0a5/images/icons/favicon-32x32.png"> <link rel="icon" type="image/png" sizes="16x16" href="https://static.arxiv.org/static/base/1.0.0a5/images/icons/favicon-16x16.png"> <link rel="manifest" href="https://static.arxiv.org/static/base/1.0.0a5/images/icons/site.webmanifest"> <link rel="mask-icon" href="https://static.arxiv.org/static/base/1.0.0a5/images/icons/safari-pinned-tab.svg" color="#b31b1b"> <link rel="shortcut icon" href="https://static.arxiv.org/static/base/1.0.0a5/images/icons/favicon.ico"> <meta name="msapplication-TileColor" content="#b31b1b"> <meta name="msapplication-config" content="images/icons/browserconfig.xml"> <meta name="theme-color" content="#b31b1b">  <title>Search | arXiv e-print repository</title> <script defer src="https://static.arxiv.org/static/base/1.0.0a5/fontawesome-free-5.11.2-web/js/all.js"></script> <link rel="stylesheet" href="https://static.arxiv.org/static/base/1.0.0a5/css/arxivstyle.css" /> <script type="text/x-mathjax-config"> MathJax.Hub.Config({ messageStyle: "none", extensions: ["tex2jax.js"], jax: ["input/TeX", "output/HTML-CSS"], tex2jax: { inlineMath: [ ['$','$'], ["\$","\$"] ], displayMath: [ ['$$','$$'], ["\\[","\\]"] ], processEscapes: true, ignoreClass: '.*', processClass: 'mathjax.*' }, TeX: { extensions: ["AMSmath.js", "AMSsymbols.js", "noErrors.js"], noErrors: { inlineDelimiters: ["$","$"], multiLine: false, style: { "font-size": "normal", "border": "" } } }, "HTML-CSS": { availableFonts: ["TeX"] } }); </script> <script src='//static.arxiv.org/MathJax-2.7.3/MathJax.js'></script> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/notification.js"></script> <link rel="stylesheet" href="https://static.arxiv.org/static/search/0.5.6/css/bulma-tooltip.min.css" /> <link rel="stylesheet" href="https://static.arxiv.org/static/search/0.5.6/css/search.css" /> <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha256-k2WSCIexGzOj3Euiig+TlR8gA0EmPjuc79OEeY5L45g=" crossorigin="anonymous"></script> <script src="https://static.arxiv.org/static/search/0.5.6/js/fieldset.js"></script> <style> radio#cf-customfield_11400 { display: none; } </style> </head> <body> <header><a href="#main-container" class="is-sr-only">Skip to main content</a>  <div class="attribution level is-marginless" role="banner"> <div class="level-left"> <a class="level-item" href="https://cornell.edu/"><img src="https://static.arxiv.org/static/base/1.0.0a5/images/cornell-reduced-white-SMALL.svg" alt="Cornell University" width="200" aria-label="logo" /></a> </div> <div class="level-right is-marginless"><p class="sponsors level-item is-marginless"><span id="support-ack-url">We gratefully acknowledge support from<br /> the Simons Foundation, <a href="https://info.arxiv.org/about/ourmembers.html">member institutions</a>, and all contributors. <a href="https://info.arxiv.org/about/donate.html">Donate</a></span></p></div> </div>  <div class="identity level is-marginless"> <div class="level-left"> <div class="level-item"> <a class="arxiv" href="https://arxiv.org/" aria-label="arxiv-logo"> <img src="https://static.arxiv.org/static/base/1.0.0a5/images/arxiv-logo-one-color-white.svg" aria-label="logo" alt="arxiv logo" width="85" style="width:85px;"/> </a> </div> </div> <div class="search-block level-right"> <form class="level-item mini-search" method="GET" action="https://arxiv.org/search"> <div class="field has-addons"> <div class="control"> <input class="input is-small" type="text" name="query" placeholder="Search..." aria-label="Search term or terms" /> <p class="help"><a href="https://info.arxiv.org/help">Help</a> | <a href="https://arxiv.org/search/advanced">Advanced Search</a></p> </div> <div class="control"> <div class="select is-small"> <select name="searchtype" aria-label="Field to search"> <option value="all" selected="selected">All fields</option> <option value="title">Title</option> <option value="author">Author</option> <option value="abstract">Abstract</option> <option value="comments">Comments</option> <option value="journal_ref">Journal reference</option> <option value="acm_class">ACM classification</option> <option value="msc_class">MSC classification</option> <option value="report_num">Report number</option> <option value="paper_id">arXiv identifier</option> <option value="doi">DOI</option> <option value="orcid">ORCID</option> <option value="author_id">arXiv author ID</option> <option value="help">Help pages</option> <option value="full_text">Full text</option> </select> </div> </div> <input type="hidden" name="source" value="header"> <button class="button is-small is-cul-darker">Search</button> </div> </form> </div> </div>  <div class="container"> <div class="user-tools is-size-7 has-text-right has-text-weight-bold" role="navigation" aria-label="User menu"> <a href="https://arxiv.org/login">Login</a> </div> </div> </header> <main class="container" id="main-container"> <div class="level is-marginless"> <div class="level-left"> <h1 class="title is-clearfix"> Showing 1–34 of 34 results for author: <span class="mathjax">Salmi, T</span> </h1> </div> <div class="level-right is-hidden-mobile">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> <div class="content"> <form method="GET" action="/search/astro-ph" aria-role="search"> Searching in archive <strong>astro-ph</strong>. <a href="/search/?searchtype=author&query=Salmi%2C+T">Search in all archives.</a> <div class="field has-addons-tablet"> <div class="control is-expanded"> <label for="query" class="hidden-label">Search term or terms</label> <input class="input is-medium" id="query" name="query" placeholder="Search term..." type="text" value="Salmi, T"> </div> <div class="select control is-medium"> <label class="is-hidden" for="searchtype">Field</label> <select class="is-medium" id="searchtype" name="searchtype"><option value="all">All fields</option><option value="title">Title</option><option selected value="author">Author(s)</option><option value="abstract">Abstract</option><option value="comments">Comments</option><option value="journal_ref">Journal reference</option><option value="acm_class">ACM classification</option><option value="msc_class">MSC classification</option><option value="report_num">Report number</option><option value="paper_id">arXiv identifier</option><option value="doi">DOI</option><option value="orcid">ORCID</option><option value="license">License (URI)</option><option value="author_id">arXiv author ID</option><option value="help">Help pages</option><option value="full_text">Full text</option></select> </div> <div class="control"> <button class="button is-link is-medium">Search</button> </div> </div> <div class="field"> <div class="control is-size-7"> <label class="radio"> <input checked id="abstracts-0" name="abstracts" type="radio" value="show"> Show abstracts </label> <label class="radio"> <input id="abstracts-1" name="abstracts" type="radio" value="hide"> Hide abstracts </label> </div> </div> <div class="is-clearfix" style="height: 2.5em"> <div class="is-pulled-right"> <a href="/search/advanced?terms-0-term=Salmi%2C+T&terms-0-field=author&size=50&order=-announced_date_first">Advanced Search</a> </div> </div> <input type="hidden" name="order" value="-announced_date_first"> <input type="hidden" name="size" value="50"> </form> <div class="level breathe-horizontal"> <div class="level-left"> <form method="GET" action="/search/"> <div style="display: none;"> <select id="searchtype" name="searchtype"><option value="all">All fields</option><option value="title">Title</option><option selected value="author">Author(s)</option><option value="abstract">Abstract</option><option value="comments">Comments</option><option value="journal_ref">Journal reference</option><option value="acm_class">ACM classification</option><option value="msc_class">MSC classification</option><option value="report_num">Report number</option><option value="paper_id">arXiv identifier</option><option value="doi">DOI</option><option value="orcid">ORCID</option><option value="license">License (URI)</option><option value="author_id">arXiv author ID</option><option value="help">Help pages</option><option value="full_text">Full text</option></select> <input id="query" name="query" type="text" value="Salmi, T"> <ul id="abstracts"><li><input checked id="abstracts-0" name="abstracts" type="radio" value="show"> <label for="abstracts-0">Show abstracts</label></li><li><input id="abstracts-1" name="abstracts" type="radio" value="hide"> <label for="abstracts-1">Hide abstracts</label></li></ul> </div> <div class="box field is-grouped is-grouped-multiline level-item"> <div class="control"> <span class="select is-small"> <select id="size" name="size"><option value="25">25</option><option selected value="50">50</option><option value="100">100</option><option value="200">200</option></select> </span> <label for="size">results per page</label>. </div> <div class="control"> <label for="order">Sort results by</label> <span class="select is-small"> <select id="order" name="order"><option selected value="-announced_date_first">Announcement date (newest first)</option><option value="announced_date_first">Announcement date (oldest first)</option><option value="-submitted_date">Submission date (newest first)</option><option value="submitted_date">Submission date (oldest first)</option><option value="">Relevance</option></select> </span> </div> <div class="control"> <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/2502.13682">arXiv:2502.13682</a> <span> [<a href="https://arxiv.org/pdf/2502.13682">pdf</a>, <a href="https://arxiv.org/format/2502.13682">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="Nuclear Theory">nucl-th</span> </div> </div> <p class="title is-5 mathjax"> Cross-Comparison of Sampling Algorithms for Pulse Profile Modeling of PSR J0740+6620 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hoogkamer%2C+M">Mariska Hoogkamer</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Buchner%2C+J">Johannes Buchner</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="2502.13682v1-abstract-short" style="display: inline;"> In the last few years, NICER data has enabled mass and radius inferences for various pulsars, and thus shed light on the equation of state for dense nuclear matter. This is achieved through a technique called pulse profile modeling. The importance of the results necessitates careful validation and testing of the robustness of the inference procedure. In this paper, we investigate the effect of sam… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.13682v1-abstract-full').style.display = 'inline'; document.getElementById('2502.13682v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.13682v1-abstract-full" style="display: none;"> In the last few years, NICER data has enabled mass and radius inferences for various pulsars, and thus shed light on the equation of state for dense nuclear matter. This is achieved through a technique called pulse profile modeling. The importance of the results necessitates careful validation and testing of the robustness of the inference procedure. In this paper, we investigate the effect of sampler choice for X-PSI (X-ray Pulse Simulation and Inference), an open-source package for pulse profile modeling and Bayesian statistical inference that has been used extensively for analysis of NICER data. We focus on the specific case of the high-mass pulsar PSR J0740+6620. Using synthetic data that mimics the most recently analyzed NICER and XMM-Newton data sets of PSR J0740+6620, we evaluate the parameter recovery performance, convergence, and computational cost for MultiNest's multimodal nested sampling algorithm and UltraNest's slice nested sampling algorithm. We find that both samplers perform reliably, producing accurate and unbiased parameter estimation results when analyzing simulated data. We also investigate the consequences for inference using the real data for PSR J0740+6620, finding that both samplers produce consistent credible intervals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.13682v1-abstract-full').style.display = 'none'; document.getElementById('2502.13682v1-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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 to PRD</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.08239">arXiv:2502.08239</a> <span> [<a href="https://arxiv.org/pdf/2502.08239">pdf</a>, <a href="https://arxiv.org/format/2502.08239">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> <p class="title is-5 mathjax"> Disk reflection and energetics from the accreting millisecond pulsar SRGA J144459.2-604207 </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=Papitto%2C+A">Alessandro Papitto</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">Sergio Campana</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=Di+Salvo%2C+T">Tiziana Di Salvo</a>, <a href="/search/astro-ph?searchtype=author&query=Baglio%2C+M+C">Maria Cristina Baglio</a>, <a href="/search/astro-ph?searchtype=author&query=Illiano%2C+G">Giulia Illiano</a>, <a href="/search/astro-ph?searchtype=author&query=La+Placa%2C+R">Riccardo La Placa</a>, <a href="/search/astro-ph?searchtype=author&query=Zanon%2C+A+M">Arianna Miraval Zanon</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Sanna%2C+A">Andrea Sanna</a>, <a href="/search/astro-ph?searchtype=author&query=Mandal%2C+M">Manoj Mandal</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="2502.08239v1-abstract-short" style="display: inline;"> Accreting millisecond pulsars (AMSPs) are excellent laboratories to study reflection spectra and their features from an accretion disk truncated by a rapidly rotating magnetosphere near the neutron star surface. These systems also exhibit thermonuclear (type-I) bursts that can provide insights on the accretion physics and fuel composition. We explore spectral properties of the AMSP SRGA J144459.2-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.08239v1-abstract-full').style.display = 'inline'; document.getElementById('2502.08239v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.08239v1-abstract-full" style="display: none;"> Accreting millisecond pulsars (AMSPs) are excellent laboratories to study reflection spectra and their features from an accretion disk truncated by a rapidly rotating magnetosphere near the neutron star surface. These systems also exhibit thermonuclear (type-I) bursts that can provide insights on the accretion physics and fuel composition. We explore spectral properties of the AMSP SRGA J144459.2-0604207 observed during the outburst that recently led to its discovery in February 2024. We aim to characterize the spectral shape of the persistent emission, both its continuum and discrete features, and to analyze type-I bursts properties. We employ XMM and NuSTAR overlapping observations taken during the most recent outburst from SRGA J1444. We perform spectral analysis of the persistent (i.e., non-bursting) emission employing a semi-phenomenological continuum model composed of a dominant thermal Comptonization plus two thermal contributions, and a physical reflection model. We also perform time-resolved spectral analysis of a type-I burst employing a blackbody model. We observe a broadened iron emission line, thus suggesting relativistic effects, supported by the physical model accounting for relativistically blurred reflection. The resulting accretion disk extends down to 6 gravitational radii, inclined at ~$53^{\circ}$, and only moderately ionized (log$尉\simeq2.3$). We observe an absorption edge at ~9.7 keV that can be interpreted as an Fe XXVI edge blueshifted by an ultrafast ($\simeq0.04$c) outflow. Our broadband observations of type-I bursts do not find evidence of photospheric radius expansion. The burst recurrence time shows a dependence on the count rate with the steepest slope ever observed in these systems. We also observe a discrepancy of ~3 between the observed and expected burst recurrence time, which we discuss in the framework of fuel composition and high NS mass scenarios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.08239v1-abstract-full').style.display = 'none'; document.getElementById('2502.08239v1-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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. Submitted to 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/2502.07471">arXiv:2502.07471</a> <span> [<a href="https://arxiv.org/pdf/2502.07471">pdf</a>, <a href="https://arxiv.org/format/2502.07471">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"> Scaling relations for the uncertainty in neutron star radius inferred from pulse profile modelling: the effect of spin rate </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bootsma%2C+E">Erik Bootsma</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</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="2502.07471v1-abstract-short" style="display: inline;"> Pulse profile modelling using X-ray data from NICER permits the inference of mass and radius for rotation-powered millisecond pulsars. This in turn constrains the equation of state of cold dense matter. Previous studies indicate that the uncertainty in the inferred radius should reduce as neutron star spin rate increases. Here we test this using one of the pipelines currently being used for pulse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.07471v1-abstract-full').style.display = 'inline'; document.getElementById('2502.07471v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.07471v1-abstract-full" style="display: none;"> Pulse profile modelling using X-ray data from NICER permits the inference of mass and radius for rotation-powered millisecond pulsars. This in turn constrains the equation of state of cold dense matter. Previous studies indicate that the uncertainty in the inferred radius should reduce as neutron star spin rate increases. Here we test this using one of the pipelines currently being used for pulse profile modelling with NICER data. We synthesize a set of pulse profiles, assuming different neutron star spin frequencies, spanning the range (25-700) Hz. All of the simulated data sets are generated with the same (single) hot spot configuration, assuming a neutron star mass and radius of $1.6\,M_{\mathrm{\odot}}$ and $10$ km. For this restricted set of synthetic data, we find no improvement in the radius credible interval once spin frequency exceeds a certain value (in this specific case $\sim 200$ Hz). If this result were to apply more generally, it would have important implications for the observing strategy for current and future pulse profile modelling missions: targets can be prioritized based on properties other than their spin frequencies, as long as we are in the millisecond range. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.07471v1-abstract-full').style.display = 'none'; document.getElementById('2502.07471v1-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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/2501.12190">arXiv:2501.12190</a> <span> [<a href="https://arxiv.org/pdf/2501.12190">pdf</a>, <a href="https://arxiv.org/format/2501.12190">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 polarized X-ray pulses from accreting millisecond pulsars with X-PSI, using different surface patterns </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Dorsman%2C+B">Bas Dorsman</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</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=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Papitto%2C+A">Alessandro Papitto</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</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="2501.12190v1-abstract-short" style="display: inline;"> We present an analysis of polarized X-ray pulses based on simulated data for accreting millisecond pulsars (AMPs). We used the open-source X-ray Pulse Simulation and Inference code (previously applied to NICER observations), that we upgraded to allow polarization analysis. We predicted neutron star parameter constraints for the Imaging X-ray Polarimetry Explorer (IXPE) and found that strong limits… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.12190v1-abstract-full').style.display = 'inline'; document.getElementById('2501.12190v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.12190v1-abstract-full" style="display: none;"> We present an analysis of polarized X-ray pulses based on simulated data for accreting millisecond pulsars (AMPs). We used the open-source X-ray Pulse Simulation and Inference code (previously applied to NICER observations), that we upgraded to allow polarization analysis. We predicted neutron star parameter constraints for the Imaging X-ray Polarimetry Explorer (IXPE) and found that strong limits on the hot region geometries can be hard to obtain if the emitting hot region is large and the number of polarized photons relatively small. However, if the star is bright enough and the hot regions are small and located so that polarization degree is higher, the observer inclination and hotspot colatitude can be constrained to a precision of within a few degrees. We also found that the shape of the hot region, whether a circle or a ring, cannot be distinguished in our most optimistic scenario. Nevertheless, future X-ray polarization missions are expected to improve the constraints, and already the recent AMP polarization detections by IXPE should help to infer the neutron star mass and radius when combined with modelling of X-ray pulse data sets that do not contain polarization information. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.12190v1-abstract-full').style.display = 'none'; document.getElementById('2501.12190v1-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 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </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, 1 table, submitted 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/2411.16528">arXiv:2411.16528</a> <span> [<a href="https://arxiv.org/pdf/2411.16528">pdf</a>, <a href="https://arxiv.org/format/2411.16528">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"> Pulse Profiles of Accreting Neutron Stars from GRMHD Simulations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Das%2C+P">Pushpita Das</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Davelaar%2C+J">Jordy Davelaar</a>, <a href="/search/astro-ph?searchtype=author&query=Porth%2C+O">Oliver Porth</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A">Anna Watts</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="2411.16528v1-abstract-short" style="display: inline;"> The pulsed X-ray emission from the neutron star surface acts as a window to study the state of matter in the neutron star interior. For accreting millisecond pulsars, the surface X-ray emission is generated from the `hotspots', which are formed as a result of magnetically channeled accretion flow hitting the stellar surface. The emission from these hotspots is modulated by stellar rotation giving… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16528v1-abstract-full').style.display = 'inline'; document.getElementById('2411.16528v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.16528v1-abstract-full" style="display: none;"> The pulsed X-ray emission from the neutron star surface acts as a window to study the state of matter in the neutron star interior. For accreting millisecond pulsars, the surface X-ray emission is generated from the `hotspots', which are formed as a result of magnetically channeled accretion flow hitting the stellar surface. The emission from these hotspots is modulated by stellar rotation giving rise to pulsations. Using global three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of the star-disk system, we investigate the accretion hotspots and the corresponding X-ray pulse properties of accreting millisecond pulsars with dipolar magnetic fields. The accretion spot morphologies in our simulations are entirely determined by the accretion columns and vary as a function of the stellar magnetic inclination. For lower inclinations, the hotspots are shaped like crescents around the magnetic axis. As we increase the inclination angle, the crescents transform into elongated bars close to the magnetic pole. We model the X-ray pulses resulting from the accretion hotspots using general-relativistic ray tracing calculations and quantify the root mean square variability of the pulsed signal. The pulse amplitudes obtained from our simulations usually range between 1 - 12% rms and are consistent with the values observed in accreting millisecond pulsars. We find that the turbulent accretion flow in the GRMHD simulations introduces significant broadband variability on a timescale similar to the stellar rotational period. We also explore the impact of electron scattering absorption and show that, along with being a key factor in determining the pulse characteristics, this also introduces significant additional variability and higher harmonics in the bolometric light curve of the accreting sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16528v1-abstract-full').style.display = 'none'; document.getElementById('2411.16528v1-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 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">Submitted to The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.14923">arXiv:2409.14923</a> <span> [<a href="https://arxiv.org/pdf/2409.14923">pdf</a>, <a href="https://arxiv.org/format/2409.14923">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="Nuclear Theory">nucl-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/10.3847/1538-4357/ad81d2">10.3847/1538-4357/ad81d2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A NICER View of PSR J1231$-$1411: A Complex Case </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Deneva%2C+J+S">Julia S. Deneva</a>, <a href="/search/astro-ph?searchtype=author&query=Ray%2C+P+S">Paul S. Ray</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Cromartie%2C+H+T">H. Thankful Cromartie</a>, <a href="/search/astro-ph?searchtype=author&query=Wolff%2C+M+T">Michael T. Wolff</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Zaven Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K">Keith Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">Wynn C. G. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Cognard%2C+I">Isma毛l Cognard</a>, <a href="/search/astro-ph?searchtype=author&query=Guillemot%2C+L">Lucas Guillemot</a>, <a href="/search/astro-ph?searchtype=author&query=Theureau%2C+G">Gilles Theureau</a>, <a href="/search/astro-ph?searchtype=author&query=Kerr%2C+M">Matthew Kerr</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="2409.14923v2-abstract-short" style="display: inline;"> Recent constraints on neutron star mass and radius have advanced our understanding of the equation of state (EOS) of cold dense matter. Some of them have been obtained by modeling the pulses of three millisecond X-ray pulsars observed by the Neutron Star Interior Composition Explorer (NICER). Here, we present a Bayesian parameter inference for a fourth pulsar, PSR J1231$-$1411, using the same tech… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14923v2-abstract-full').style.display = 'inline'; document.getElementById('2409.14923v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.14923v2-abstract-full" style="display: none;"> Recent constraints on neutron star mass and radius have advanced our understanding of the equation of state (EOS) of cold dense matter. Some of them have been obtained by modeling the pulses of three millisecond X-ray pulsars observed by the Neutron Star Interior Composition Explorer (NICER). Here, we present a Bayesian parameter inference for a fourth pulsar, PSR J1231$-$1411, using the same technique with NICER and XMM-Newton data. When applying a broad mass-inclination prior from radio timing measurements and the emission region geometry model that can best explain the data, we find likely converged results only when using a limited radius prior. If limiting the radius to be consistent with the previous observational constraints and EOS analyses, we infer the radius to be $12.6 \pm 0.3$ km and the mass to be $1.04_{-0.03}^{+0.05}$ $M_\odot$, each reported as the posterior credible interval bounded by the $16\,\%$ and $84\,\%$ quantiles. If using an uninformative prior but limited between $10$ and $14$ km, we find otherwise similar results, but $R_{\mathrm{eq}} = 13.5_{-0.5}^{+0.3}$ km for the radius. In both cases, we find a nonantipodal hot region geometry where one emitting spot is at the equator or slightly above, surrounded by a large colder region, and where a noncircular hot region lies close to southern rotational pole. If using a wider radius prior, we only find solutions that fit the data significantly worse. We discuss the challenges in finding the better fitting solutions, possibly related to the weak interpulse feature in the pulse profile. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14923v2-abstract-full').style.display = 'none'; document.getElementById('2409.14923v2-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 23 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">23 pages, 13 figures (2 of which are figure sets), 3 tables, published in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 976 58 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.07908">arXiv:2409.07908</a> <span> [<a href="https://arxiv.org/pdf/2409.07908">pdf</a>, <a href="https://arxiv.org/format/2409.07908">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"> Parameter constraints for accreting millisecond pulsars with synthetic NICER data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Dorsman%2C+B">Bas Dorsman</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Kamath%2C+S">Satish Kamath</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Chakrabarty%2C+D">Deepto Chakrabarty</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="2409.07908v1-abstract-short" style="display: inline;"> Pulse profile modelling (PPM) is a technique for inferring mass, radius and hotspot properties of millisecond pulsars. PPM is now regularly used for analysis of rotation-powered millisecond pulsars (RMPs) with data from the Neutron Star Interior Composition ExploreR (NICER). Extending PPM to accreting millisecond pulsars (AMPs) is attractive, because they are a different source class featuring bri… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.07908v1-abstract-full').style.display = 'inline'; document.getElementById('2409.07908v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.07908v1-abstract-full" style="display: none;"> Pulse profile modelling (PPM) is a technique for inferring mass, radius and hotspot properties of millisecond pulsars. PPM is now regularly used for analysis of rotation-powered millisecond pulsars (RMPs) with data from the Neutron Star Interior Composition ExploreR (NICER). Extending PPM to accreting millisecond pulsars (AMPs) is attractive, because they are a different source class featuring bright X-ray radiation from hotspots powered by accretion. In this paper, we present a modification of one of the PPM codes, X-PSI, so that it can be used for AMPs. In particular, we implement a model of an accretion disc and atmosphere model appropriate for the hotspots of AMPs, and improve the overall computational efficiency. We then test parameter recovery with synthetic NICER data in two scenarios with reasonable parameters for AMPs. We find in the first scenario, where the hotspot is large, that we are able to tightly and accurately constrain all parameters including mass and radius. In the second scenario, which is a high inclination system with a smaller hotspot, we find degeneracy between a subset of model parameters and a slight bias in the inferred mass and radius. This analysis of synthetic data lays the ground work for future analysis of AMPs with NICER data. Such an analysis could be complemented by future (joint) analysis of polarization data from the Imaging X-ray Polarimetry Explorer (IXPE). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.07908v1-abstract-full').style.display = 'none'; document.getElementById('2409.07908v1-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 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">14 pages, 5 figures, 3 tables. Paper submitted 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/2408.00608">arXiv:2408.00608</a> <span> [<a href="https://arxiv.org/pdf/2408.00608">pdf</a>, <a href="https://arxiv.org/ps/2408.00608">ps</a>, <a href="https://arxiv.org/format/2408.00608">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/10.1051/0004-6361/202451775">10.1051/0004-6361/202451775 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of Polarized X-Ray Emission from the Accreting Millisecond Pulsar SRGA J144459.2-604207 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Papitto%2C+A">Alessandro Papitto</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=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Illiano%2C+G">Giulia Illiano</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=Ambrosino%2C+F">Filippo Ambrosino</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Baglio%2C+M+C">Maria Cristina Baglio</a>, <a href="/search/astro-ph?searchtype=author&query=Ballocco%2C+C">Caterina Ballocco</a>, <a href="/search/astro-ph?searchtype=author&query=Burderi%2C+L">Luciano Burderi</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">Sergio Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Zelati%2C+F+C">Francesco Coti Zelati</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Salvo%2C+T">Tiziana Di Salvo</a>, <a href="/search/astro-ph?searchtype=author&query=La+Placa%2C+R">Riccardo La Placa</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Long%2C+S">Sinan Long</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Zanon%2C+A+M">Arianna Miraval Zanon</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Sanna%2C+A">Andrea Sanna</a>, <a href="/search/astro-ph?searchtype=author&query=Stella%2C+L">Luigi Stella</a>, <a href="/search/astro-ph?searchtype=author&query=Strohmayer%2C+T">Tod Strohmayer</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</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="2408.00608v2-abstract-short" style="display: inline;"> We report on the discovery of polarized X-ray emission from an accreting millisecond pulsar. During a 10-day-long coverage of the February 2024 outburst of SRGA J144459.2-604207, the Imaging X-ray Polarimetry Explorer (IXPE) detected an average polarization degree of the 2-8 keV emission of 2.3% +/- 0.4% at an angle of 59掳 +/- 6掳 (East of North; uncertainties quoted at the 1$蟽$ confidence level).… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.00608v2-abstract-full').style.display = 'inline'; document.getElementById('2408.00608v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.00608v2-abstract-full" style="display: none;"> We report on the discovery of polarized X-ray emission from an accreting millisecond pulsar. During a 10-day-long coverage of the February 2024 outburst of SRGA J144459.2-604207, the Imaging X-ray Polarimetry Explorer (IXPE) detected an average polarization degree of the 2-8 keV emission of 2.3% +/- 0.4% at an angle of 59掳 +/- 6掳 (East of North; uncertainties quoted at the 1$蟽$ confidence level). The polarized signal shows a significant energy dependence with a degree of 4.0% +/- 0.5% between 3 and 6 keV and < 1.5% (90% c.l.) in the 2-3 keV range. We used NICER, XMM-Newton, and NuSTAR observations to obtain an accurate pulse timing solution and perform a phase-resolved polarimetric analysis of IXPE data. We did not detect any significant variability of the Stokes parameters Q and U with the spin and the orbital phases. We used the relativistic rotating vector model to show that a moderately fan-beam emission from two point-like spots at a small magnetic obliquity ($\simeq$ 10掳) is compatible with the observed pulse profile and polarization properties. IXPE also detected 52 type-I X-ray bursts, with a recurrence time $螖t_{rec}$ increasing from 2 to 8 h as a function of the observed count rate $C$ as as $螖t_{rec} \simeq C^{-0.8}$ We stacked the emission observed during all the bursts and obtained an upper limit on the polarization degree of 8.5% (90% c.l.). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.00608v2-abstract-full').style.display = 'none'; document.getElementById('2408.00608v2-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 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">10 pages, 10 figures, accepted for publication by 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 694, A37 (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.06790">arXiv:2407.06790</a> <span> [<a href="https://arxiv.org/pdf/2407.06790">pdf</a>, <a href="https://arxiv.org/format/2407.06790">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Experiment">nucl-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-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/10.3847/2041-8213/ad5f02">10.3847/2041-8213/ad5f02 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rutherford%2C+N">Nathan Rutherford</a>, <a href="/search/astro-ph?searchtype=author&query=Mendes%2C+M">Melissa Mendes</a>, <a href="/search/astro-ph?searchtype=author&query=Svensson%2C+I">Isak Svensson</a>, <a href="/search/astro-ph?searchtype=author&query=Schwenk%2C+A">Achim Schwenk</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Hebeler%2C+K">Kai Hebeler</a>, <a href="/search/astro-ph?searchtype=author&query=Keller%2C+J">Jonas Keller</a>, <a href="/search/astro-ph?searchtype=author&query=Prescod-Weinstein%2C+C">Chanda Prescod-Weinstein</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Raaijmakers%2C+G">Geert Raaijmakers</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Timmerman%2C+P">Patrick Timmerman</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Lattimer%2C+J+M">James M. Lattimer</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="2407.06790v2-abstract-short" style="display: inline;"> Pulse profile modeling of X-ray data from NICER is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory ($蠂$EFT), and masses and tidal deformabilities inferred from gravitational wave detections of binary neutron star mergers, this has lead to a steady improvement in our understanding of the dense matter equa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06790v2-abstract-full').style.display = 'inline'; document.getElementById('2407.06790v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06790v2-abstract-full" style="display: none;"> Pulse profile modeling of X-ray data from NICER is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory ($蠂$EFT), and masses and tidal deformabilities inferred from gravitational wave detections of binary neutron star mergers, this has lead to a steady improvement in our understanding of the dense matter equation of state (EOS). Here we consider the impact of several new results: the radius measurement for the 1.42$\,M_\odot$ pulsar PSR J0437$-$4715 presented by Choudhury et al. (2024), updates to the masses and radii of PSR J0740$+$6620 and PSR J0030$+$0451, and new $蠂$EFT results for neutron star matter up to 1.5 times nuclear saturation density. Using two different high-density EOS extensions -- a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS) -- we find the radius of a 1.4$\,M_\odot$ (2.0$\,M_\odot$) neutron star to be constrained to the 95% credible ranges $12.28^{+0.50}_{-0.76}\,$km ($12.33^{+0.70}_{-1.34}\,$km) for the PP model and $12.01^{+0.56}_{-0.75}\,$km ($11.55^{+0.94}_{-1.09}\,$km) for the CS model. The maximum neutron star mass is predicted to be $2.15^{+0.14}_{-0.16}\,$$M_\odot$ and $2.08^{+0.28}_{-0.16}\,$$M_\odot$ for the PP and CS model, respectively. We explore the sensitivity of our results to different orders and different densities up to which $蠂$EFT is used, and show how the astrophysical observations provide constraints for the pressure at intermediate densities. Moreover, we investigate the difference $R_{2.0} - R_{1.4}$ of the radius of 2$\,M_\odot$ and 1.4$\,M_\odot$ neutron stars within our EOS inference. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06790v2-abstract-full').style.display = 'none'; document.getElementById('2407.06790v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">23 pages, 15 figures; published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ Letters, 971, L19 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.06789">arXiv:2407.06789</a> <span> [<a href="https://arxiv.org/pdf/2407.06789">pdf</a>, <a href="https://arxiv.org/format/2407.06789">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-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/10.3847/2041-8213/ad5a6f">10.3847/2041-8213/ad5a6f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437$\unicode{x2013}$4715 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Riley%2C+T+E">Thomas E. Riley</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Dorsman%2C+B">Bas Dorsman</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Ray%2C+P+S">Paul S. Ray</a>, <a href="/search/astro-ph?searchtype=author&query=Reardon%2C+D+J">Daniel J. Reardon</a>, <a href="/search/astro-ph?searchtype=author&query=Remillard%2C+R+A">Ronald A. Remillard</a>, <a href="/search/astro-ph?searchtype=author&query=Bilous%2C+A+V">Anna V. Bilous</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">Daniela Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Lattimer%2C+J+M">James M. Lattimer</a>, <a href="/search/astro-ph?searchtype=author&query=Rutherford%2C+N">Nathan Rutherford</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Zaven Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K+C">Keith C. Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">Wynn C. G. Ho</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="2407.06789v1-abstract-short" style="display: inline;"> We report Bayesian inference of the mass, radius and hot X-ray emitting region properties - using data from the Neutron Star Interior Composition ExploreR (NICER) - for the brightest rotation-powered millisecond X-ray pulsar PSR J0437$\unicode{x2013}$4715. Our modeling is conditional on informative tight priors on mass, distance and binary inclination obtained from radio pulsar timing using the Pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06789v1-abstract-full').style.display = 'inline'; document.getElementById('2407.06789v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06789v1-abstract-full" style="display: none;"> We report Bayesian inference of the mass, radius and hot X-ray emitting region properties - using data from the Neutron Star Interior Composition ExploreR (NICER) - for the brightest rotation-powered millisecond X-ray pulsar PSR J0437$\unicode{x2013}$4715. Our modeling is conditional on informative tight priors on mass, distance and binary inclination obtained from radio pulsar timing using the Parkes Pulsar Timing Array (PPTA) (Reardon et al. 2024), and we use NICER background models to constrain the non-source background, cross-checking with data from XMM-Newton. We assume two distinct hot emitting regions, and various parameterized hot region geometries that are defined in terms of overlapping circles; while simplified, these capture many of the possibilities suggested by detailed modeling of return current heating. For the preferred model identified by our analysis we infer a mass of $M = 1.418 \pm 0.037$ M$_\odot$ (largely informed by the PPTA mass prior) and an equatorial radius of $R = 11.36^{+0.95}_{-0.63}$ km, each reported as the posterior credible interval bounded by the 16% and 84% quantiles. This radius favors softer dense matter equations of state and is highly consistent with constraints derived from gravitational wave measurements of neutron star binary mergers. The hot regions are inferred to be non-antipodal, and hence inconsistent with a pure centered dipole magnetic field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06789v1-abstract-full').style.display = 'none'; document.getElementById('2407.06789v1-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">27 pages, 16 figures, + appendices. Accepted in ApJL. Data files and reproduction package available in Zenodo</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.14466">arXiv:2406.14466</a> <span> [<a href="https://arxiv.org/pdf/2406.14466">pdf</a>, <a href="https://arxiv.org/format/2406.14466">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="Nuclear Theory">nucl-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/10.3847/1538-4357/ad5f1f">10.3847/1538-4357/ad5f1f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Radius of the High-mass Pulsar PSR J0740+6620 with 3.6 yr of NICER Data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Riley%2C+T+E">Thomas E. Riley</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Wolff%2C+M+T">Michael T. Wolff</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Zaven Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Chakrabarty%2C+D">Deepto Chakrabarty</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K">Keith Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">Wynn C. G. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">Daniela Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Ludlam%2C+R+M">Renee M. Ludlam</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Ray%2C+P+S">Paul S. Ray</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="2406.14466v2-abstract-short" style="display: inline;"> We report an updated analysis of the radius, mass, and heated surface regions of the massive pulsar PSR J0740+6620 using Neutron Star Interior Composition Explorer (NICER) data from 2018 September 21 to 2022 April 21, a substantial increase in data set size compared to previous analyses. Using a tight mass prior from radio timing measurements and jointly modeling the new NICER data with XMM-Newton… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.14466v2-abstract-full').style.display = 'inline'; document.getElementById('2406.14466v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.14466v2-abstract-full" style="display: none;"> We report an updated analysis of the radius, mass, and heated surface regions of the massive pulsar PSR J0740+6620 using Neutron Star Interior Composition Explorer (NICER) data from 2018 September 21 to 2022 April 21, a substantial increase in data set size compared to previous analyses. Using a tight mass prior from radio timing measurements and jointly modeling the new NICER data with XMM-Newton data, the inferred equatorial radius and gravitational mass are $12.49_{-0.88}^{+1.28}$ km and $2.073_{-0.069}^{+0.069}$ $M_\odot$ respectively, each reported as the posterior credible interval bounded by the $16\,\%$ and $84\,\%$ quantiles, with an estimated systematic error $\lesssim 0.1$ km. This result was obtained using the best computationally feasible sampler settings providing a strong radius lower limit but a slightly more uncertain radius upper limit. The inferred radius interval is also close to the $R=12.76_{-1.02}^{+1.49}$ km obtained by Dittmann et al., when they require the radius to be less than $16$ km as we do. The results continue to disfavor very soft equations of state for dense matter, with $R<11.15$ km for this high-mass pulsar excluded at the $95\,\%$ probability. The results do not depend significantly on the assumed cross-calibration uncertainty between NICER and XMM-Newton. Using simulated data that resemble the actual observations, we also show that our pipeline is capable of recovering parameters for the inferred models reported in this paper. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.14466v2-abstract-full').style.display = 'none'; document.getElementById('2406.14466v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 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, 9 figures (2 of which are figure sets), 2 tables, published in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 974 294 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.07285">arXiv:2406.07285</a> <span> [<a href="https://arxiv.org/pdf/2406.07285">pdf</a>, <a href="https://arxiv.org/format/2406.07285">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="General Relativity and Quantum Cosmology">gr-qc</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/ad7255">10.3847/1538-4357/ad7255 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring Waveform Variations among Neutron Star Ray-tracing Codes for Complex Emission Geometries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Dittmann%2C+A+J">Alexander J. Dittmann</a>, <a href="/search/astro-ph?searchtype=author&query=Miller%2C+M+C">M. Coleman Miller</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Wolff%2C+M+T">Michael T. Wolff</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Zaven Arzoumanian</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="2406.07285v2-abstract-short" style="display: inline;"> Pulse Profile Modeling (PPM), the technique used to infer mass, radius and geometric parameters for rotation-powered millisecond pulsars using data from the Neutron Star Interior Composition Explorer (NICER), relies on relativistic ray-tracing of thermal X-ray photons from hot spots on the neutron star surface to the observer. To verify our ray-tracing codes we have in the past conducted cross-tes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07285v2-abstract-full').style.display = 'inline'; document.getElementById('2406.07285v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.07285v2-abstract-full" style="display: none;"> Pulse Profile Modeling (PPM), the technique used to infer mass, radius and geometric parameters for rotation-powered millisecond pulsars using data from the Neutron Star Interior Composition Explorer (NICER), relies on relativistic ray-tracing of thermal X-ray photons from hot spots on the neutron star surface to the observer. To verify our ray-tracing codes we have in the past conducted cross-tests for simple hot spot geometries, focusing primarily on the implementation of the space-time model. In this paper, we present verification for test problems that explore the more complex hot spot geometries that are now being employed in the NICER PPM analyses. We conclude that the accuracy of our computed waveforms is in general sufficiently high for analyses of current NICER data sets. We have however identified some extreme configurations where extra care may be needed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07285v2-abstract-full').style.display = 'none'; document.getElementById('2406.07285v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 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">Updated to version accepted by The Astrophysical Journal following their review process</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 975 202 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.10717">arXiv:2405.10717</a> <span> [<a href="https://arxiv.org/pdf/2405.10717">pdf</a>, <a href="https://arxiv.org/format/2405.10717">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/stae2398">10.1093/mnras/stae2398 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraining the Properties of the Thermonuclear Burst Oscillation Source XTE J1814-338 Through Pulse Profile Modelling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Bilous%2C+A">Anna Bilous</a>, <a href="/search/astro-ph?searchtype=author&query=Galloway%2C+D+K">Duncan K. Galloway</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Wateren%2C+E">Emma van der Wateren</a>, <a href="/search/astro-ph?searchtype=author&query=Khalsa%2C+G+P">Guru Partap Khalsa</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Buchner%2C+J">Johannes Buchner</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">Valery Suleimanov</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="2405.10717v2-abstract-short" style="display: inline;"> Pulse profile modelling (PPM) is a comprehensive relativistic ray-tracing technique employed to determine the properties of neutron stars. In this study, we apply this technique to the Type I X-ray burster and accretion-powered millisecond pulsar XTE J1814-338, extracting its fundamental properties using PPM of its thermonuclear burst oscillations. Using data from its 2003 outburst, and a single u… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.10717v2-abstract-full').style.display = 'inline'; document.getElementById('2405.10717v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.10717v2-abstract-full" style="display: none;"> Pulse profile modelling (PPM) is a comprehensive relativistic ray-tracing technique employed to determine the properties of neutron stars. In this study, we apply this technique to the Type I X-ray burster and accretion-powered millisecond pulsar XTE J1814-338, extracting its fundamental properties using PPM of its thermonuclear burst oscillations. Using data from its 2003 outburst, and a single uniform temperature hot spot model, we infer XTE J1814-338 to be located at a distance of $7.2^{+0.3}_{-0.4}$ kpc, with a mass of $1.21^{+0.05}_{-0.05}$ M$_\odot$ and an equatorial radius of $7.0^{+0.4}_{-0.4}$ km. Our results also offer insight into the time evolution of the hot spot but point to some potential shortcomings of the single uniform temperature hot spot model. We explore the implications of this result, including what we can learn about thermonuclear burst oscillation mechanisms and the importance of modelling the accretion contribution to the emission during the burst. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.10717v2-abstract-full').style.display = 'none'; document.getElementById('2405.10717v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 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">Accepted for publication in MNRAS. The Zenodo link is public</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> MN-24-1065-MJ.R2 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> MNRAS, 535, 1507 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.13058">arXiv:2401.13058</a> <span> [<a href="https://arxiv.org/pdf/2401.13058">pdf</a>, <a href="https://arxiv.org/format/2401.13058">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/10.1051/0004-6361/202449318">10.1051/0004-6361/202449318 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</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=Di+Marco%2C+A">Alessandro Di Marco</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=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">Swati Ravi</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Kajava%2C+J+J+E">Jari J. E. Kajava</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Rogantini%2C+D">Daniele Rogantini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Done%2C+C">Chris Done</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Nitindala%2C+A+P">Anagha P. Nitindala</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a> , et al. (84 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="2401.13058v2-abstract-short" style="display: inline;"> Weakly magnetized neutron stars in X-ray binaries show complex phenomenology with several spectral components that can be associated with the accretion disk, boundary and/or spreading layer, a corona, and a wind. Spectroscopic information alone is, however, not enough to disentangle these components. Additional information about the nature of the spectral components and in particular the geometry… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.13058v2-abstract-full').style.display = 'inline'; document.getElementById('2401.13058v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.13058v2-abstract-full" style="display: none;"> Weakly magnetized neutron stars in X-ray binaries show complex phenomenology with several spectral components that can be associated with the accretion disk, boundary and/or spreading layer, a corona, and a wind. Spectroscopic information alone is, however, not enough to disentangle these components. Additional information about the nature of the spectral components and in particular the geometry of the emission region can be provided by X-ray polarimetry. One of the objects of the class, a bright, persistent, and rather peculiar galactic Type I X-ray burster was observed with the Imaging X-ray Polarimetry Explorer (IXPE) and the X-ray Multi-Mirror Mission Newton (XMM-Newton). Using the XMM-Newton data we estimated the current state of the source as well as detected strong absorption lines associated with the accretion disk wind. IXPE data showed the source to be significantly polarized in the 2-8 keV energy band with the overall polarization degree (PD) of 1.4% at a polarization angle (PA) of -2 degrees (errors at 68% confidence level). During the two-day long observation, we detected rotation of the PA by about 70 degrees with the corresponding changes in the PD from 2% to non-detectable and then up to 5%. These variations in polarization properties are not accompanied by visible changes in spectroscopic characteristics. The energy-resolved polarimetric analysis showed a significant change in polarization, from being strongly dependent on energy at the beginning of the observation to being almost constant with energy in the later parts of the observation. As a possible interpretation, we suggest the presence of a constant component of polarization, strong wind scattering, or different polarization of the two main spectral components with individually peculiar behavior. The rotation of the PA suggests a 30-degree misalignment of the neutron star spin from the orbital axis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.13058v2-abstract-full').style.display = 'none'; document.getElementById('2401.13058v2-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 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">12 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 688, A170 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.08142">arXiv:2312.08142</a> <span> [<a href="https://arxiv.org/pdf/2312.08142">pdf</a>, <a href="https://arxiv.org/format/2312.08142">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/10.1051/0004-6361/202348153">10.1051/0004-6361/202348153 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Effects of scattering in the accretion funnel on the pulse profiles of accreting millisecond pulsars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ahlberg%2C+V">Varpu Ahlberg</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</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="2312.08142v1-abstract-short" style="display: inline;"> The hotspot emission of accreting millisecond pulsars (AMPs) undergoes scattering in the accretion flow between the disk inner radius and the neutron star surface. The scattering optical depth of the flow depends on the photon emission angle, which is a function of the pulse phase, and reaches its maximum when the hotspot is closest to the observer. At sufficiently large optical depths the observe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.08142v1-abstract-full').style.display = 'inline'; document.getElementById('2312.08142v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.08142v1-abstract-full" style="display: none;"> The hotspot emission of accreting millisecond pulsars (AMPs) undergoes scattering in the accretion flow between the disk inner radius and the neutron star surface. The scattering optical depth of the flow depends on the photon emission angle, which is a function of the pulse phase, and reaches its maximum when the hotspot is closest to the observer. At sufficiently large optical depths the observed pulse profile should develop a secondary minimum, the depth of which depends on the accretion rate and the emission geometry. Such a dip evolving with the accretion rate might explain the phase shift and pulse profile evolution observed in AMPs during outbursts. Accounting for scattering is important for accurate modeling of the AMP pulse profiles in order to improve the accuracy of determination of the neutron star parameters, such as their masses and radii. In this paper we present a simplified analytical model for the Thomson optical depth of the accretion funnel, and apply it to simulating the pulse profiles. We show that scattering in the accretion funnel has a significant effect on the pulse profiles at accretion rates of $\dot{M} \gtrsim 10^{-10}~{M}_\odot\, \mathrm{yr}^{-1}$. Our model predicts a gradual evolution of the pulse profile with the accretion rate that appears to be consistent with the observations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.08142v1-abstract-full').style.display = 'none'; document.getElementById('2312.08142v1-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 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">8 pages, 6 figures, accepted for publication in A&A on 16 November 2023</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.02329">arXiv:2309.02329</a> <span> [<a href="https://arxiv.org/pdf/2309.02329">pdf</a>, <a href="https://arxiv.org/format/2309.02329">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/10.1051/0004-6361/202346833">10.1051/0004-6361/202346833 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Polarized radiation from an accretion shock in accreting millisecond pulsars using exact Compton scattering formalism </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</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="2309.02329v1-abstract-short" style="display: inline;"> Pulse profiles of accreting millisecond pulsars can be used to determine neutron star (NS) parameters, such as their masses and radii, and therefore provide constraints on the equation of state of cold dense matter. Information obtained by the Imaging X-ray Polarimetry Explorer (IXPE) can be used to decipher pulsar inclination and magnetic obliquity, providing ever tighter constraints on other par… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.02329v1-abstract-full').style.display = 'inline'; document.getElementById('2309.02329v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.02329v1-abstract-full" style="display: none;"> Pulse profiles of accreting millisecond pulsars can be used to determine neutron star (NS) parameters, such as their masses and radii, and therefore provide constraints on the equation of state of cold dense matter. Information obtained by the Imaging X-ray Polarimetry Explorer (IXPE) can be used to decipher pulsar inclination and magnetic obliquity, providing ever tighter constraints on other parameters. In this paper, we develop a new emission model for accretion-powered millisecond pulsars based on thermal Comptonization in an accretion shock above the NS surface. The shock structure was approximated by an isothermal plane-parallel slab and the Stokes parameters of the emergent radiation were computed as a function of the zenith angle and energy for different values of the electron temperature, the Thomson optical depth of the slab, and the temperature of the seed blackbody photons. We show that our Compton scattering model leads to a significantly lower polarization degree of the emitted radiation compared to the previously used Thomson scattering model. We computed a large grid of shock models, which can be combined with pulse profile modeling techniques both with and without polarization included. In this work, we used the relativistic rotating vector model for the oblate NS in order to produce the observed Stokes parameters as a function of the pulsar phase. Furthermore, we simulated the data to be produced by IXPE and obtained constraints on model parameters using nested sampling. The developed methods can also be used in the analysis of the data from future satellites, such as the enhanced X-ray Timing and Polarimetry mission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.02329v1-abstract-full').style.display = 'none'; document.getElementById('2309.02329v1-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 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">Accepted to A&A on 11 August 2023</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 678, A99 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.12895">arXiv:2308.12895</a> <span> [<a href="https://arxiv.org/pdf/2308.12895">pdf</a>, <a href="https://arxiv.org/format/2308.12895">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/stad3595">10.1093/mnras/stad3595 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pulse Profile Modelling of Thermonuclear Burst Oscillations II: Handling variability </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Buchner%2C+J">Johannes Buchner</a>, <a href="/search/astro-ph?searchtype=author&query=Meisel%2C+Z">Zach Meisel</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">Valery Suleimanov</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="2308.12895v2-abstract-short" style="display: inline;"> Pulse profile modelling is a relativistic ray-tracing technique that can be used to infer masses, radii and geometric parameters of neutron stars. In a previous study, we looked at the performance of this technique when applied to thermonuclear burst oscillations from accreting neutron stars. That study showed that ignoring the variability associated with burst oscillation sources resulted in sign… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.12895v2-abstract-full').style.display = 'inline'; document.getElementById('2308.12895v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.12895v2-abstract-full" style="display: none;"> Pulse profile modelling is a relativistic ray-tracing technique that can be used to infer masses, radii and geometric parameters of neutron stars. In a previous study, we looked at the performance of this technique when applied to thermonuclear burst oscillations from accreting neutron stars. That study showed that ignoring the variability associated with burst oscillation sources resulted in significant biases in the inferred mass and radius, particularly for the high count rates that are nominally required to obtain meaningful constraints. In this follow-on study, we show that the bias can be mitigated by slicing the bursts into shorter segments where variability can be neglected, and jointly fitting the segments. Using this approach, the systematic uncertainties on the mass and radius are brought within the range of the statistical uncertainty. With about 10$^6$ source counts, this yields uncertainties of approximately 10% for both the mass and radius. However, this modelling strategy requires substantial computational resources. We also confirm that the posterior distributions of the mass and radius obtained from multiple bursts of the same source can be merged to produce outcomes comparable to that of a single burst with an equivalent total number of counts. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.12895v2-abstract-full').style.display = 'none'; document.getElementById('2308.12895v2-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 24 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. The Zenodo link is now public</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.09469">arXiv:2308.09469</a> <span> [<a href="https://arxiv.org/pdf/2308.09469">pdf</a>, <a href="https://arxiv.org/format/2308.09469">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-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/10.3847/1538-4357/acfb83">10.3847/1538-4357/acfb83 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An updated mass-radius analysis of the 2017-2018 NICER data set of PSR J0030+0451 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Riley%2C+T+E">Thomas E. Riley</a>, <a href="/search/astro-ph?searchtype=author&query=Ray%2C+P+S">Paul S. Ray</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Chakrabarty%2C+D">Deepto Chakrabarty</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">Wynn C. G. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">Daniela Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Wadiasingh%2C+Z">Zorawar Wadiasingh</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="2308.09469v1-abstract-short" style="display: inline;"> In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterising dense matter. Two independent analyses found a mass of $\sim 1.3-1.4\,\mathrm{M_\odot}$ and a radius of $\sim 13\,$km. They also both found that the hot spots were all located on the same hemisphere, opposi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.09469v1-abstract-full').style.display = 'inline'; document.getElementById('2308.09469v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.09469v1-abstract-full" style="display: none;"> In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterising dense matter. Two independent analyses found a mass of $\sim 1.3-1.4\,\mathrm{M_\odot}$ and a radius of $\sim 13\,$km. They also both found that the hot spots were all located on the same hemisphere, opposite to the observer, and that at least one of them had a significantly elongated shape. Here we reanalyse, in greater detail, the same NICER data set, incorporating the effects of an updated NICER response matrix and using an upgraded analysis framework. We expand the adopted models and jointly analyse also XMM-Newton data, which enables us to better constrain the fraction of observed counts coming from PSR J0030+0451. Adopting the same models used in previous publications, we find consistent results, although with more stringent inference requirements. We also find a multi-modal structure in the posterior surface. This becomes crucial when XMM-Newton data is accounted for. Including the corresponding constraints disfavors the main solutions found previously, in favor of the new and more complex models. These have inferred masses and radii of $\sim [1.4 \mathrm{M_\odot}, 11.5$ km] and $\sim [1.7 \mathrm{M_\odot}, 14.5$ km], depending on the assumed model. They display configurations that do not require the two hot spots generating the observed X-rays to be on the same hemisphere, nor to show very elongated features, and point instead to the presence of temperature gradients and the need to account for them. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.09469v1-abstract-full').style.display = 'none'; document.getElementById('2308.09469v1-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, 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">35 pages, 11 figures, 7 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ, 961, 62 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.09319">arXiv:2308.09319</a> <span> [<a href="https://arxiv.org/pdf/2308.09319">pdf</a>, <a href="https://arxiv.org/format/2308.09319">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-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/10.3847/1538-4357/acf49d">10.3847/1538-4357/acf49d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Atmospheric Effects on Neutron Star Parameter Constraints with NICER </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">Wynn C. G. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Dorsman%2C+B">Bas Dorsman</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</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="2308.09319v2-abstract-short" style="display: inline;"> We present an analysis of the effects of uncertainties in the atmosphere models on the radius, mass, and other neutron star parameter constraints for the NICER observations of rotation-powered millisecond pulsars. To date, NICER has applied the X-ray pulse profile modeling technique to two millisecond-period pulsars: PSR J0030+0451 and the high-mass pulsar PSR J0740+6620. These studies have common… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.09319v2-abstract-full').style.display = 'inline'; document.getElementById('2308.09319v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.09319v2-abstract-full" style="display: none;"> We present an analysis of the effects of uncertainties in the atmosphere models on the radius, mass, and other neutron star parameter constraints for the NICER observations of rotation-powered millisecond pulsars. To date, NICER has applied the X-ray pulse profile modeling technique to two millisecond-period pulsars: PSR J0030+0451 and the high-mass pulsar PSR J0740+6620. These studies have commonly assumed a deep-heated, fully ionized hydrogen atmosphere model, although they have explored the effects of partial-ionization and helium composition in some cases. Here, we extend that exploration and also include new models with partially ionized carbon composition, externally heated hydrogen, and an empirical atmospheric beaming parameterization to explore deviations in the expected anisotropy of the emitted radiation. None of the studied atmosphere cases have any significant influence on the inferred radius of PSR J0740+6620, possibly due to its X-ray faintness, tighter external constraints, and/or viewing geometry. In the case of PSR J0030+0451, both the composition and ionization state could significantly alter the inferred radius. However, based on the evidence (prior predictive probability of the data), partially ionized hydrogen and carbon atmospheres are disfavored. The difference in the evidence for ionized hydrogen and helium atmospheres is too small to be decisive for most cases, but the inferred radius for helium models trends to larger sizes around or above 14-15 km. External heating or deviations in the beaming that are less than $5\,\%$ at emission angles smaller than 60 degrees, on the other hand, have no significant effect on the inferred radius. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.09319v2-abstract-full').style.display = 'none'; document.getElementById('2308.09319v2-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 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">26 pages, 12 figures (2 of which are figure sets), 3 tables. Published in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 956 138 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.08409">arXiv:2308.08409</a> <span> [<a href="https://arxiv.org/pdf/2308.08409">pdf</a>, <a href="https://arxiv.org/format/2308.08409">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-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/10.3847/1538-4357/acf9a0">10.3847/1538-4357/acf9a0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-PSI Parameter Recovery for Temperature Map Configurations Inspired by PSR J0030+0451 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Riley%2C+T+E">Thomas E. Riley</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="2308.08409v1-abstract-short" style="display: inline;"> In the last few years, the NICER collaboration has provided mass and radius inferences, via pulse profile modeling, for two pulsars: PSR J0030+0451 and PSR J0740+6620. Given the importance of these results for constraining the equation of state of dense nuclear matter, it is crucial to validate them and test their robustness. We therefore explore the reliability of these results and their sensitiv… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.08409v1-abstract-full').style.display = 'inline'; document.getElementById('2308.08409v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.08409v1-abstract-full" style="display: none;"> In the last few years, the NICER collaboration has provided mass and radius inferences, via pulse profile modeling, for two pulsars: PSR J0030+0451 and PSR J0740+6620. Given the importance of these results for constraining the equation of state of dense nuclear matter, it is crucial to validate them and test their robustness. We therefore explore the reliability of these results and their sensitivity to analysis settings and random processes, including noise, focusing on the specific case of PSR J0030+0451. We use X-PSI, one of the two main analysis pipelines currently employed by the NICER collaboration for mass and radius inferences. With synthetic data that mimic the PSR J0030+0451 NICER data set, we evaluate the recovery performances of X-PSI under conditions never tested before, including complex modeling of the thermally emitting neutron star surface. For the test cases explored, our results suggest that X-PSI is capable of recovering the true mass and radius within reasonable credible intervals. This work also reveals the main vulnerabilities of the analysis: a significant dependence on noise and the presence of multi-modal structure in the posterior surface. Noise particularly impacts our sensitivity to the analysis settings and widths of the posterior distributions. The multi-modal structure in the posterior suggests that biases could be present if the analysis is unable to exhaustively explore the parameter space. Convergence testing, to ensure an adequate coverage of the parameter space and a suitable representation of the posterior distribution, is one possible solution to these challenges. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.08409v1-abstract-full').style.display = 'none'; document.getElementById('2308.08409v1-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> 16 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">27 pages, 13 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ, 959, 55 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.01770">arXiv:2304.01770</a> <span> [<a href="https://arxiv.org/pdf/2304.01770">pdf</a>, <a href="https://arxiv.org/format/2304.01770">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/stad1030">10.1093/mnras/stad1030 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pulse Profile Modeling of Thermonuclear Burst Oscillations I: The Effect of Neglecting Variability </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kini%2C+Y">Yves Kini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Fenne%2C+S">Siem Fenne</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Meisel%2C+Z">Zach Meisel</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">Valery Suleimanov</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="2304.01770v1-abstract-short" style="display: inline;"> We study the effects of the time-variable properties of thermonuclear X-ray bursts on modeling their millisecond-period burst oscillations. We apply the pulse profile modeling technique that is being used in the analysis of rotation-powered millisecond pulsars by the Neutron Star Interior Composition Explorer (NICER) to infer masses, radii, and geometric parameters of neutron stars. By simulating… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.01770v1-abstract-full').style.display = 'inline'; document.getElementById('2304.01770v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.01770v1-abstract-full" style="display: none;"> We study the effects of the time-variable properties of thermonuclear X-ray bursts on modeling their millisecond-period burst oscillations. We apply the pulse profile modeling technique that is being used in the analysis of rotation-powered millisecond pulsars by the Neutron Star Interior Composition Explorer (NICER) to infer masses, radii, and geometric parameters of neutron stars. By simulating and analyzing a large set of models, we show that overlooking burst time-scale variability in temperatures and sizes of the hot emitting regions can result in substantial bias in the inferred mass and radius. To adequately infer neutron star properties, it is essential to develop a model for the time variable properties or invest a substantial amount of computational time in segmenting the data into non-varying pieces. We discuss prospects for constraints from proposed future X-ray telescopes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.01770v1-abstract-full').style.display = 'none'; document.getElementById('2304.01770v1-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 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 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/2212.09778">arXiv:2212.09778</a> <span> [<a href="https://arxiv.org/pdf/2212.09778">pdf</a>, <a href="https://arxiv.org/format/2212.09778">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/acad81">10.3847/2041-8213/acad81 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Timing analysis of the 2022 outburst of the accreting millisecond X-ray pulsar SAX J1808.4$-$3658: hints of an orbital shrinking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Illiano%2C+G">Giulia Illiano</a>, <a href="/search/astro-ph?searchtype=author&query=Papitto%2C+A">Alessandro Papitto</a>, <a href="/search/astro-ph?searchtype=author&query=Sanna%2C+A">Andrea Sanna</a>, <a href="/search/astro-ph?searchtype=author&query=Bult%2C+P">Peter Bult</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosino%2C+F">Filippo Ambrosino</a>, <a href="/search/astro-ph?searchtype=author&query=Zanon%2C+A+M">Arianna Miraval Zanon</a>, <a href="/search/astro-ph?searchtype=author&query=Zelati%2C+F+C">Francesco Coti Zelati</a>, <a href="/search/astro-ph?searchtype=author&query=Stella%2C+L">Luigi Stella</a>, <a href="/search/astro-ph?searchtype=author&query=Altamirano%2C+D">Diego Altamirano</a>, <a href="/search/astro-ph?searchtype=author&query=Baglio%2C+M+C">Maria Cristina Baglio</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">Enrico Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Burderi%2C+L">Luciano Burderi</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=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=di+Salvo%2C+T">Tiziana di Salvo</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">Carlo Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Marino%2C+A">Alessio Marino</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</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="2212.09778v2-abstract-short" style="display: inline;"> We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4$-$3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of $\simeq 1\times10^{36} \, \mathrm{erg \, s^{-1}}$ in about a week, the pulsar entered in a $\sim 1$ month-long reflaring stage. Comparison of the average puls… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.09778v2-abstract-full').style.display = 'inline'; document.getElementById('2212.09778v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.09778v2-abstract-full" style="display: none;"> We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4$-$3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of $\simeq 1\times10^{36} \, \mathrm{erg \, s^{-1}}$ in about a week, the pulsar entered in a $\sim 1$ month-long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of $\dot谓_{\textrm{SD}}=-(1.15\pm0.06)\times 10^{-15} \, \mathrm{Hz\,s^{-1}}$, compatible with the spin-down torque of a $\approx 10^{26} \, \mathrm{G \, cm^3}$ rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behaviour of the orbit is dominated by a $\sim 11 \, \mathrm{s}$ modulation of the orbital phase epoch consistent with a $\sim 21 \, \mathrm{yr}$ period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.09778v2-abstract-full').style.display = 'none'; document.getElementById('2212.09778v2-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 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">11 pages, 3 figures, 1 table. 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/2209.12840">arXiv:2209.12840</a> <span> [<a href="https://arxiv.org/pdf/2209.12840">pdf</a>, <a href="https://arxiv.org/format/2209.12840">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-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/10.3847/1538-4357/ac983d">10.3847/1538-4357/ac983d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Radius of PSR J0740+6620 from NICER with NICER Background Estimates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Vinciguerra%2C+S">Serena Vinciguerra</a>, <a href="/search/astro-ph?searchtype=author&query=Choudhury%2C+D">Devarshi Choudhury</a>, <a href="/search/astro-ph?searchtype=author&query=Riley%2C+T+E">Thomas E. Riley</a>, <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Remillard%2C+R+A">Ronald A. Remillard</a>, <a href="/search/astro-ph?searchtype=author&query=Ray%2C+P+S">Paul S. Ray</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Zaven Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Chirenti%2C+C">Cecilia Chirenti</a>, <a href="/search/astro-ph?searchtype=author&query=Dittmann%2C+A+J">Alexander J. Dittmann</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K+C">Keith C. Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">Wynn C. G. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Miller%2C+M+C">M. Coleman Miller</a>, <a href="/search/astro-ph?searchtype=author&query=Morsink%2C+S+M">Sharon M. Morsink</a>, <a href="/search/astro-ph?searchtype=author&query=Wadiasingh%2C+Z">Zorawar Wadiasingh</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="2209.12840v2-abstract-short" style="display: inline;"> We report a revised analysis for the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, studied previously with joint fits to NICER and XMM-Newton data by Riley et al. (2021) and Miller et al. (2021). We perform a similar Bayesian estimation for the pulse-profile model parameters, except that instead of fitting simultaneously the XMM-Newton data, we use the bes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.12840v2-abstract-full').style.display = 'inline'; document.getElementById('2209.12840v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.12840v2-abstract-full" style="display: none;"> We report a revised analysis for the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, studied previously with joint fits to NICER and XMM-Newton data by Riley et al. (2021) and Miller et al. (2021). We perform a similar Bayesian estimation for the pulse-profile model parameters, except that instead of fitting simultaneously the XMM-Newton data, we use the best available NICER background estimates to constrain the number of photons detected from the source. This approach eliminates any potential issues in the cross-calibration between these two instruments, providing thus an independent check of the robustness of the analysis. The obtained neutron star parameter constraints are compatible with the already published results, with a slight dependence on how conservative the imposed background limits are. A tighter lower limit causes the inferred radius to increase, and a tighter upper limit causes it to decrease. We also extend the study of the inferred emission geometry to examine the degree of deviation from antipodality of the hot regions. We show that there is a significant offset to an antipodal spot configuration, mainly due to the non-half-cycle azimuthal separation of the two emitting spots. The offset angle from the antipode is inferred to be above 25 degrees with 84% probability. This seems to exclude a centered-dipolar magnetic field in PSR J0740+6620. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.12840v2-abstract-full').style.display = 'none'; document.getElementById('2209.12840v2-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 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">29 pages, 18 figures (10 of which are figure sets), 1 animation, 10 tables. Published in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 941 150 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.09744">arXiv:2009.09744</a> <span> [<a href="https://arxiv.org/pdf/2009.09744">pdf</a>, <a href="https://arxiv.org/format/2009.09744">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/10.1051/0004-6361/202039470">10.1051/0004-6361/202039470 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Neutron star parameter constraints for accretion-powered millisecond pulsars from the simulated IXPE data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Korsman%2C+K">Karri Korsman</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</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> </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="2009.09744v2-abstract-short" style="display: inline;"> We have simulated the X-ray polarization data that can be obtained with the Imaging X-ray Polarimetry Explorer, when observing accretion-powered millisecond pulsars. We estimated the necessary exposure times for SAX J1808.4$-$3658 in order to obtain different accuracies in the measured time-dependent Stokes profiles integrated over all energy channels. We found that the measured relative errors de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.09744v2-abstract-full').style.display = 'inline'; document.getElementById('2009.09744v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.09744v2-abstract-full" style="display: none;"> We have simulated the X-ray polarization data that can be obtained with the Imaging X-ray Polarimetry Explorer, when observing accretion-powered millisecond pulsars. We estimated the necessary exposure times for SAX J1808.4$-$3658 in order to obtain different accuracies in the measured time-dependent Stokes profiles integrated over all energy channels. We found that the measured relative errors depend strongly on the relative configuration of the observer and the emitting hotspot. The improvement in the minimum relative error in Stokes $Q$ and $U$ parameters as a function of observing time $t$ scales as $1/\sqrt{t}$, and spans the range from 30-90% with 200 ks exposure time to 20-60% with 500 ks exposure time (in case of data binned in 19 phase bins). The simulated data were also used to predict how accurate measurements of the geometrical parameters of the neutron star can be made when modelling only $Q$ and $U$ parameters, but not the flux. We found that the observer inclination and the hotspot co-latitude could be determined with better than 10 deg accuracy for most of the cases we considered. These measurements can be used to further constrain neutron star mass and radius when combined with modelling of the X-ray pulse profile. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.09744v2-abstract-full').style.display = 'none'; document.getElementById('2009.09744v2-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 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 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">12 pages, 11 figures, published 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 646, A23 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.08852">arXiv:2009.08852</a> <span> [<a href="https://arxiv.org/pdf/2009.08852">pdf</a>, <a href="https://arxiv.org/format/2009.08852">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/10.1051/0004-6361/202039134">10.1051/0004-6361/202039134 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Oblate Schwarzschild approximation for polarized radiation from rapidly rotating neutron stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=N%C3%A4ttil%C3%A4%2C+J">Joonas N盲ttil盲</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</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="2009.08852v1-abstract-short" style="display: inline;"> We have developed a complete theory for the calculation of the observed Stokes parameters for radiation emitted from the surface of a rapidly rotating neutron star (NS) using the oblate Schwarzschild approximation. We accounted for the rotation of the polarization plane due to relativistic effects along the path from the stellar surface to the observer. The results were shown to agree with those o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.08852v1-abstract-full').style.display = 'inline'; document.getElementById('2009.08852v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.08852v1-abstract-full" style="display: none;"> We have developed a complete theory for the calculation of the observed Stokes parameters for radiation emitted from the surface of a rapidly rotating neutron star (NS) using the oblate Schwarzschild approximation. We accounted for the rotation of the polarization plane due to relativistic effects along the path from the stellar surface to the observer. The results were shown to agree with those obtained by performing full numerical general relativistic ray-tracing with the \textsc{arcmancer} code. We showed that the obtained polarization angle (PA) profiles may differ substantially from those derived for a spherical star. We demonstrated that assuming incorrect shape for the star can lead to biased constraints for NS parameters when fitting the polarization data. Using a simplified model, we also made a rough estimate of how accurately the geometrical parameters of an accreting NS can be determined using the X-ray polarization measurements of upcoming polarimeters like the Imaging X-ray Polarimeter Explorer (IXPE) or the enhanced X-ray Timing and Polarimetry (eXTP) mission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.08852v1-abstract-full').style.display = 'none'; document.getElementById('2009.08852v1-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 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">11 pages, 10 figures, accepted 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 643, A84 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.11427">arXiv:2002.11427</a> <span> [<a href="https://arxiv.org/pdf/2002.11427">pdf</a>, <a href="https://arxiv.org/format/2002.11427">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/10.1051/0004-6361/202037824">10.1051/0004-6361/202037824 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetospheric return-current-heated atmospheres of rotation-powered millisecond pulsars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</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=N%C3%A4ttil%C3%A4%2C+J">Joonas N盲ttil盲</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</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="2002.11427v3-abstract-short" style="display: inline;"> We computed accurate atmosphere models of rotation-powered millisecond pulsars in which the polar caps of a neutron star (NS) are externally heated by magnetospheric return currents. The external ram pressure, energy losses, and stopping depth of the penetrating charged particles were computed self-consistently with the atmosphere model, instead of assuming a simplified deep-heated atmosphere in r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.11427v3-abstract-full').style.display = 'inline'; document.getElementById('2002.11427v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.11427v3-abstract-full" style="display: none;"> We computed accurate atmosphere models of rotation-powered millisecond pulsars in which the polar caps of a neutron star (NS) are externally heated by magnetospheric return currents. The external ram pressure, energy losses, and stopping depth of the penetrating charged particles were computed self-consistently with the atmosphere model, instead of assuming a simplified deep-heated atmosphere in radiative equilibrium. We used exact Compton scattering formalism to model the properties of the emergent X-ray radiation. The deep-heating approximation was found to be valid only if most of the heat originates from ultra-relativistic bombarding particles with Lorentz factors of $纬\gtrsim 100$. In the opposite regime, the atmosphere attains a distinct two-layer structure with an overheated optically thin skin on top of an optically thick cool plasma. The overheated skin strongly modifies the emergent radiation: it produces a Compton-upscattered high-energy tail in the spectrum and alters the radiation beaming pattern from limb darkening to limb brightening for emitted hard X-rays. This kind of drastic change in the emission properties can have a significant impact on the inferred NS pulse profile parameters as performed, for example, by Neutron star Interior Composition ExploreR. Finally, the connection between the energy distribution of the return current particles and the atmosphere emission properties offers a new tool to probe the exact physics of pulsar magnetospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.11427v3-abstract-full').style.display = 'none'; document.getElementById('2002.11427v3-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 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">13 pages, 10 figures, published 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 641, A15 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.10190">arXiv:1907.10190</a> <span> [<a href="https://arxiv.org/pdf/1907.10190">pdf</a>, <a href="https://arxiv.org/format/1907.10190">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> </div> </div> <p class="title is-5 mathjax"> The X-ray Polarization Probe mission concept </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Jahoda%2C+K">Keith Jahoda</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Kislat%2C+F">Fabian Kislat</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H">Herman Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Okajima%2C+T">Takashi Okajima</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Angelini%2C+L">Lorella Angelini</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=Baring%2C+M">Matthew Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Baumgartner%2C+W">Wayne Baumgartner</a>, <a href="/search/astro-ph?searchtype=author&query=Bellazzini%2C+R">Ronaldo Bellazzini</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccolo Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Caiazzo%2C+I">Ilaria Caiazzo</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Coppi%2C+P">Paolo Coppi</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">Alessandra De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Monte%2C+E">Ettore Del Monte</a>, <a href="/search/astro-ph?searchtype=author&query=Dexter%2C+J">Jason Dexter</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Dovciak%2C+M">Michal Dovciak</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="1907.10190v1-abstract-short" style="display: inline;"> The X-ray Polarization Probe (XPP) is a second generation X-ray polarimeter following up on the Imaging X-ray Polarimetry Explorer (IXPE). The XPP will offer true broadband polarimetery over the wide 0.2-60 keV bandpass in addition to imaging polarimetry from 2-8 keV. The extended energy bandpass and improvements in sensitivity will enable the simultaneous measurement of the polarization of severa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.10190v1-abstract-full').style.display = 'inline'; document.getElementById('1907.10190v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.10190v1-abstract-full" style="display: none;"> The X-ray Polarization Probe (XPP) is a second generation X-ray polarimeter following up on the Imaging X-ray Polarimetry Explorer (IXPE). The XPP will offer true broadband polarimetery over the wide 0.2-60 keV bandpass in addition to imaging polarimetry from 2-8 keV. The extended energy bandpass and improvements in sensitivity will enable the simultaneous measurement of the polarization of several emission components. These measurements will give qualitatively new information about how compact objects work, and will probe fundamental physics, i.e. strong-field quantum electrodynamics and strong gravity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.10190v1-abstract-full').style.display = 'none'; document.getElementById('1907.10190v1-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, 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">submitted to Astrophysics Decadal Survey as a State of the Profession white paper</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1903.04373">arXiv:1903.04373</a> <span> [<a href="https://arxiv.org/pdf/1903.04373">pdf</a>, <a href="https://arxiv.org/format/1903.04373">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/10.1051/0004-6361/201935442">10.1051/0004-6361/201935442 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Effects of Compton scattering on the neutron star radius constraints in rotation-powered millisecond pulsars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">T. Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">V. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</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="1903.04373v2-abstract-short" style="display: inline;"> The aim of this work is to study the possible effects and biases on the radius constraints for rotation-powered millisecond pulsars when using Thomson approximation to describe electron scattering in the atmosphere models, instead of using exact formulation for Compton scattering. We compare the differences between the two models in the energy spectrum and angular distribution of the emitted radia… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.04373v2-abstract-full').style.display = 'inline'; document.getElementById('1903.04373v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1903.04373v2-abstract-full" style="display: none;"> The aim of this work is to study the possible effects and biases on the radius constraints for rotation-powered millisecond pulsars when using Thomson approximation to describe electron scattering in the atmosphere models, instead of using exact formulation for Compton scattering. We compare the differences between the two models in the energy spectrum and angular distribution of the emitted radiation. We also analyse a self-generated synthetic phase-resolved energy spectrum, based on Compton atmosphere and the most X-ray luminous rotation-powered millisecond pulsars observed by the Neutron star Interior Composition ExploreR (NICER). We derive constraints for the neutron star parameters using both the Compton and Thomson models. The results show that the method works by reproducing the correct parameters with the Compton model. However, biases are found in size and the temperature of the emitting hot spot, when using the Thomson model. The constraints on the radius are still not significantly changed, and therefore the Thomson model seems to be adequate if we are interested only in the radius measurements using NICER. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.04373v2-abstract-full').style.display = 'none'; document.getElementById('1903.04373v2-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 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 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">6 pages, 9 figures, published 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 627, A39 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.04023">arXiv:1812.04023</a> <span> [<a href="https://arxiv.org/pdf/1812.04023">pdf</a>, <a href="https://arxiv.org/format/1812.04023">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/10.1007/s11433-017-9186-1">10.1007/s11433-017-9186-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observatory science with eXTP </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zand%2C+J+J+M+i+%27">Jean J. M. in 't Zand</a>, <a href="/search/astro-ph?searchtype=author&query=Bozzo%2C+E">Enrico Bozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Qu%2C+J">Jinlu Qu</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+X">Xiang-Dong Li</a>, <a href="/search/astro-ph?searchtype=author&query=Amati%2C+L">Lorenzo Amati</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+Y">Yang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Drake%2C+S+A">Stephen A. Drake</a>, <a href="/search/astro-ph?searchtype=author&query=Hernanz%2C+M">Margarita Hernanz</a>, <a href="/search/astro-ph?searchtype=author&query=Jenke%2C+P+A">Peter A. Jenke</a>, <a href="/search/astro-ph?searchtype=author&query=Maccarone%2C+T+J">Thomas J. Maccarone</a>, <a href="/search/astro-ph?searchtype=author&query=Mahmoodifar%2C+S">Simin Mahmoodifar</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=De+Rosa%2C+A">Alessandra De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Rossi%2C+E+M">Elena M. Rossi</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">Antonia Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Sala%2C+G">Gloria Sala</a>, <a href="/search/astro-ph?searchtype=author&query=Stratta%2C+G">Giulia Stratta</a>, <a href="/search/astro-ph?searchtype=author&query=Tauris%2C+T+M">Thomas M. Tauris</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">Joern Wilms</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+X">Xuefeng Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Zhou%2C+P">Ping Zhou</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Altamirano%2C+D">Diego Altamirano</a> , et al. (159 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="1812.04023v1-abstract-short" style="display: inline;"> In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to stu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.04023v1-abstract-full').style.display = 'inline'; document.getElementById('1812.04023v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.04023v1-abstract-full" style="display: none;"> In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.04023v1-abstract-full').style.display = 'none'; document.getElementById('1812.04023v1-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 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </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 Sci. China Phys. Mech. Astron. (2019)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.04021">arXiv:1812.04021</a> <span> [<a href="https://arxiv.org/pdf/1812.04021">pdf</a>, <a href="https://arxiv.org/format/1812.04021">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/10.1007/s11433-017-9188-4">10.1007/s11433-017-9188-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dense matter with eXTP </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Watts%2C+A+L">Anna L. Watts</a>, <a href="/search/astro-ph?searchtype=author&query=Yu%2C+W">Wenfei Yu</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shu Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+S">Sudip Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Bogdanov%2C+S">Slavko Bogdanov</a>, <a href="/search/astro-ph?searchtype=author&query=Ji%2C+L">Long Ji</a>, <a href="/search/astro-ph?searchtype=author&query=Patruno%2C+A">Alessandro Patruno</a>, <a href="/search/astro-ph?searchtype=author&query=Riley%2C+T+E">Thomas E. Riley</a>, <a href="/search/astro-ph?searchtype=author&query=Bakala%2C+P">Pavel Bakala</a>, <a href="/search/astro-ph?searchtype=author&query=Baykal%2C+A">Altan Baykal</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+F">Federico Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bombaci%2C+I">Ignazio Bombaci</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+E">Edward Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Cavecchi%2C+Y">Yuri Cavecchi</a>, <a href="/search/astro-ph?searchtype=author&query=Chakrabarty%2C+D">Deepto Chakrabarty</a>, <a href="/search/astro-ph?searchtype=author&query=Chenevez%2C+J">J茅r么me Chenevez</a>, <a href="/search/astro-ph?searchtype=author&query=Degenaar%2C+N">Nathalie Degenaar</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Santo%2C+M">Melania Del Santo</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Salvo%2C+T">Tiziana Di Salvo</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>, <a href="/search/astro-ph?searchtype=author&query=Ferdman%2C+R+D">Robert D. Ferdman</a>, <a href="/search/astro-ph?searchtype=author&query=Feroci%2C+M">Marco Feroci</a>, <a href="/search/astro-ph?searchtype=author&query=Gambino%2C+A+F">Angelo F. Gambino</a> , et al. (51 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="1812.04021v1-abstract-short" style="display: inline;"> In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, b… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.04021v1-abstract-full').style.display = 'inline'; document.getElementById('1812.04021v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.04021v1-abstract-full" style="display: none;"> In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.04021v1-abstract-full').style.display = 'none'; document.getElementById('1812.04021v1-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 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </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 Sci. China Phys. Mech. Astron. (2019)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.00098">arXiv:1809.00098</a> <span> [<a href="https://arxiv.org/pdf/1809.00098">pdf</a>, <a href="https://arxiv.org/ps/1809.00098">ps</a>, <a href="https://arxiv.org/format/1809.00098">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/aade8e">10.3847/1538-4357/aade8e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evidence for the photoionization absorption edge in a photospheric radius expansion X-ray burst from GRS 1747$-$312 in Terzan 6 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Li%2C+Z">Zhaosheng Li</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Falanga%2C+M">Maurizio Falanga</a>, <a href="/search/astro-ph?searchtype=author&query=N%C3%A4ttil%C3%A4%2C+J">Joonas N盲ttil盲</a>, <a href="/search/astro-ph?searchtype=author&query=Xu%2C+R">Renxin Xu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1809.00098v2-abstract-short" style="display: inline;"> Thermonuclear X-ray bursts on the surface of neutron stars (NSs) can enrich photosphere with metals, which may imprint the photoionization edges on the burst spectra. We report here the discovery of absorption edges in the spectra of the type I X-ray burst from the NS low-mass X-ray binary GRS 1747$-$312 in Terzan 6 during observations by the Rossi X-ray Timing Explorer. We find that the edge ener… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.00098v2-abstract-full').style.display = 'inline'; document.getElementById('1809.00098v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.00098v2-abstract-full" style="display: none;"> Thermonuclear X-ray bursts on the surface of neutron stars (NSs) can enrich photosphere with metals, which may imprint the photoionization edges on the burst spectra. We report here the discovery of absorption edges in the spectra of the type I X-ray burst from the NS low-mass X-ray binary GRS 1747$-$312 in Terzan 6 during observations by the Rossi X-ray Timing Explorer. We find that the edge energy evolves from $9.45\pm0.51$ keV to $\sim6$ keV and then back to $9.44\pm0.40$ keV during the photospheric radius expansion phase and remains at $8.06\pm0.66$ keV in the cooling tail. The photoionization absorption edges of hydrogen-like Ni, Fe or Fe/Ni mixture and the bound-bound transitions of metals may be responsible for the observed spectral features. The ratio of the measured absorption edge energy in the cooling tail to the laboratory value of hydrogen-like Ni(Fe) edge energy allows us to estimate the gravitational redshift factor $1+z=1.34\pm0.11$($1+z=1.15\pm0.09$). The evolution of the spectral parameters during the cooling tail are well-described by the metal-rich atmosphere models. The combined constraints on the NS mass and radius from the direct cooling method and the tidal deformability strongly suggest very high atmospheric abundance of the iron group elements and limit the distance to the source to $11\pm1$ kpc. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.00098v2-abstract-full').style.display = 'none'; document.getElementById('1809.00098v2-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 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </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">matches the published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, 866:53 (7pp), 2018 October 10 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.01149">arXiv:1805.01149</a> <span> [<a href="https://arxiv.org/pdf/1805.01149">pdf</a>, <a href="https://arxiv.org/format/1805.01149">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/10.1051/0004-6361/201833348">10.1051/0004-6361/201833348 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bayesian parameter constraints for neutron star masses and radii using X-ray timing observations of accretion-powered millisecond pulsars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">T. Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=N%C3%A4ttil%C3%A4%2C+J">J. N盲ttil盲</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</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="1805.01149v2-abstract-short" style="display: inline;"> We present a Bayesian method to constrain the masses and radii of neutron stars (NSs) using the information encoded in the X-ray pulse profiles of accreting millisecond pulsars. We model the shape of the pulses using "oblate Schwarzschild" approximation, which takes into account the deformed shape of the star together with the special and general relativistic corrections to the photon trajectories… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.01149v2-abstract-full').style.display = 'inline'; document.getElementById('1805.01149v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.01149v2-abstract-full" style="display: none;"> We present a Bayesian method to constrain the masses and radii of neutron stars (NSs) using the information encoded in the X-ray pulse profiles of accreting millisecond pulsars. We model the shape of the pulses using "oblate Schwarzschild" approximation, which takes into account the deformed shape of the star together with the special and general relativistic corrections to the photon trajectories and angles. The spectrum of the radiation is obtained from an empirical model of Comptonization in a hot slab in which a fraction of seed blackbody photons is scattered into a power-law component. By using an affine-invariant Markov chain Monte Carlo ensemble sampling method, we obtain posterior probability distributions for the different model parameters, especially for the mass and the radius. To test the robustness of our method, we first analyzed self-generated synthetic data with known model parameters. Similar analysis was then applied for the observations of SAX J1808.4-3658 by the Rossi X-ray Timing Explorer (RXTE). The results show that our method can reproduce the model parameters of the synthetic data, and that accurate constraints for the radius can be obtained using the RXTE pulse profile observations if the mass is a priori known. For a mass in the range 1.5-1.8 Msun, the radius of the NS in SAX J1808.4-3658 is constrained between 9 and 13 km. If the mass is accurately known, the radius can be determined with an accuracy of 5% (68% credibility). For example, for the mass of 1.7 Msun the equatorial radius is Req = 11.9+0.5 -0.4 km. Finally, we show that further improvements can be obtained when the X-ray polarization data from the Imaging X-ray Polarimeter Explorer will become available. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.01149v2-abstract-full').style.display = 'none'; document.getElementById('1805.01149v2-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, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </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, 9 figures, published 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 618, A161 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1409.6467">arXiv:1409.6467</a> <span> [<a href="https://arxiv.org/pdf/1409.6467">pdf</a>, <a href="https://arxiv.org/ps/1409.6467">ps</a>, <a href="https://arxiv.org/format/1409.6467">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/10.1051/0004-6361/201424338">10.1051/0004-6361/201424338 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The nature of the late achromatic bump in GRB 120326A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Melandri%2C+A">A. Melandri</a>, <a href="/search/astro-ph?searchtype=author&query=Virgili%2C+F+J">F. J. Virgili</a>, <a href="/search/astro-ph?searchtype=author&query=Guidorzi%2C+C">C. Guidorzi</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+M+G">M. G. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Kobayashi%2C+S">S. Kobayashi</a>, <a href="/search/astro-ph?searchtype=author&query=Mundell%2C+C+G">C. G. Mundell</a>, <a href="/search/astro-ph?searchtype=author&query=Gomboc%2C+A">A. Gomboc</a>, <a href="/search/astro-ph?searchtype=author&query=Dintinjana%2C+B">B. Dintinjana</a>, <a href="/search/astro-ph?searchtype=author&query=Hentunen%2C+V+-">V. -P. Hentunen</a>, <a href="/search/astro-ph?searchtype=author&query=Japelj%2C+J">J. Japelj</a>, <a href="/search/astro-ph?searchtype=author&query=Kopa%C4%8D%2C+D">D. Kopa膷</a>, <a href="/search/astro-ph?searchtype=author&query=Kuroda%2C+D">D. Kuroda</a>, <a href="/search/astro-ph?searchtype=author&query=Morgan%2C+A+N">A. N. Morgan</a>, <a href="/search/astro-ph?searchtype=author&query=Steele%2C+I+A">I. A. Steele</a>, <a href="/search/astro-ph?searchtype=author&query=Quadri%2C+U">U. Quadri</a>, <a href="/search/astro-ph?searchtype=author&query=Arici%2C+G">G. Arici</a>, <a href="/search/astro-ph?searchtype=author&query=Arnold%2C+D">D. Arnold</a>, <a href="/search/astro-ph?searchtype=author&query=Girelli%2C+R">R. Girelli</a>, <a href="/search/astro-ph?searchtype=author&query=Hanayama%2C+H">H. Hanayama</a>, <a href="/search/astro-ph?searchtype=author&query=Kawai%2C+N">N. Kawai</a>, <a href="/search/astro-ph?searchtype=author&query=Miku%C5%BE%2C+H">H. Miku啪</a>, <a href="/search/astro-ph?searchtype=author&query=Nissinen%2C+M">M. Nissinen</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">T. Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+R+J">R. J. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Strabla%2C+L">L. Strabla</a> , et al. (2 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="1409.6467v1-abstract-short" style="display: inline;"> The long ${\it Swift}$ gamma-ray burst GRB 120326A at redshift $z=1.798$ exhibited a multi-band light curve with a striking feature: a late-time, long-lasting achromatic rebrightening, rarely seen in such events. Peaking in optical and X-ray bands $\sim 35$ ks ($\sim 12.5$ ks in the GRB rest frame) after the 70-s GRB prompt burst, the feature brightens nearly two orders of magnitude above the unde… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1409.6467v1-abstract-full').style.display = 'inline'; document.getElementById('1409.6467v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1409.6467v1-abstract-full" style="display: none;"> The long ${\it Swift}$ gamma-ray burst GRB 120326A at redshift $z=1.798$ exhibited a multi-band light curve with a striking feature: a late-time, long-lasting achromatic rebrightening, rarely seen in such events. Peaking in optical and X-ray bands $\sim 35$ ks ($\sim 12.5$ ks in the GRB rest frame) after the 70-s GRB prompt burst, the feature brightens nearly two orders of magnitude above the underlying optical power-law decay. Modelling the multiwavelength light curves, we investigate possible causes of the rebrightening in the context of the standard fireball model. We exclude a range of scenarios for the origin of this feature: reverse-shock flash, late-time forward shock peak due to the passage of the maximal synchrotron frequency through the optical band, late central engine optical/X-ray flares, interaction between the expanding blast wave and a density enhancement in the circumburst medium and gravitational microlensing. Instead we conclude that the achromatic rebrightening may be caused by a refreshed forward shock or a geometrical effect. In addition, we identify an additional component after the end of the prompt emission, that shapes the observed X-ray and optical light curves differently, ruling out a single overall emission component to explain the observed early time emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1409.6467v1-abstract-full').style.display = 'none'; document.getElementById('1409.6467v1-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 September, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2014. </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, 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 572, A55 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1111.0283">arXiv:1111.0283</a> <span> [<a href="https://arxiv.org/pdf/1111.0283">pdf</a>, <a href="https://arxiv.org/ps/1111.0283">ps</a>, <a href="https://arxiv.org/format/1111.0283">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/10.1088/0004-637X/751/2/90">10.1088/0004-637X/751/2/90 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Panchromatic observations of the textbook GRB 110205A: constraining physical mechanisms of prompt emission and afterglow </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zheng%2C+W">W. Zheng</a>, <a href="/search/astro-ph?searchtype=author&query=Shen%2C+R+F">R. F. Shen</a>, <a href="/search/astro-ph?searchtype=author&query=Sakamoto%2C+T">T. Sakamoto</a>, <a href="/search/astro-ph?searchtype=author&query=Beardmore%2C+A+P">A. P. Beardmore</a>, <a href="/search/astro-ph?searchtype=author&query=De+Pasquale%2C+M">M. De Pasquale</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+X+F">X. F. Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Gorosabel%2C+J">J. Gorosabel</a>, <a href="/search/astro-ph?searchtype=author&query=Urata%2C+Y">Y. Urata</a>, <a href="/search/astro-ph?searchtype=author&query=Sugita%2C+S">S. Sugita</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+B">B. Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Pozanenko%2C+A">A. Pozanenko</a>, <a href="/search/astro-ph?searchtype=author&query=Nissinen%2C+M">M. Nissinen</a>, <a href="/search/astro-ph?searchtype=author&query=Sahu%2C+D+K">D. K. Sahu</a>, <a href="/search/astro-ph?searchtype=author&query=Im%2C+M">M. Im</a>, <a href="/search/astro-ph?searchtype=author&query=Ukwatta%2C+T+N">T. N. Ukwatta</a>, <a href="/search/astro-ph?searchtype=author&query=Andreev%2C+M">M. Andreev</a>, <a href="/search/astro-ph?searchtype=author&query=Klunko%2C+E">E. Klunko</a>, <a href="/search/astro-ph?searchtype=author&query=Volnova%2C+A">A. Volnova</a>, <a href="/search/astro-ph?searchtype=author&query=Akerlof%2C+C+W">C. W. Akerlof</a>, <a href="/search/astro-ph?searchtype=author&query=Anto%2C+P">P. Anto</a>, <a href="/search/astro-ph?searchtype=author&query=Barthelmy%2C+S+D">S. D. Barthelmy</a>, <a href="/search/astro-ph?searchtype=author&query=Breeveld%2C+A">A. Breeveld</a>, <a href="/search/astro-ph?searchtype=author&query=Carsenty%2C+U">U. Carsenty</a>, <a href="/search/astro-ph?searchtype=author&query=Castillo-Carri%27on%2C+S">S. Castillo-Carri'on</a>, <a href="/search/astro-ph?searchtype=author&query=Castro-Tirado%2C+A+J">A. J. Castro-Tirado</a> , et al. (34 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="1111.0283v2-abstract-short" style="display: inline;"> We present a comprehensive analysis of a bright, long duration (T90 ~ 257 s) GRB 110205A at redshift z= 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb and BOOTES telescopes when the GRB was still radiating in the gamma-ray band. Nearly 200 s of observations were obtained simultaneously from optical, X-ray to gamma-ray, which makes it one of the exceptional cases to study… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1111.0283v2-abstract-full').style.display = 'inline'; document.getElementById('1111.0283v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1111.0283v2-abstract-full" style="display: none;"> We present a comprehensive analysis of a bright, long duration (T90 ~ 257 s) GRB 110205A at redshift z= 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb and BOOTES telescopes when the GRB was still radiating in the gamma-ray band. Nearly 200 s of observations were obtained simultaneously from optical, X-ray to gamma-ray, which makes it one of the exceptional cases to study the broadband spectral energy distribution across 6 orders of magnitude in energy during the prompt emission phase. By fitting the time resolved prompt spectra, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard GRB synchrotron emission model in the fast cooling regime. Although the prompt optical emission is brighter than the extrapolation of the best fit X/gamma-ray spectra, it traces the gamma-ray light curve shape, suggesting a relation to the prompt high energy emission. The synchrotron + SSC scenario is disfavored by the data, but the models invoking a pair of internal shocks or having two emission regions can interpret the data well. Shortly after prompt emission (~ 1100 s), a bright (R = 14.0) optical emission hump with very steep rise (alpha ~ 5.5) was observed which we interpret as the emission from the reverse shock. It is the first time that the rising phase of a reverse shock component has been closely observed. The full optical and X-ray afterglow lightcurves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high quality prompt emission and afterglow data allow us to apply the standard fireball shock model to extract valuable information about the GRB including the radiation mechanism, radius of prompt emission R, initial Lorentz factor of the outflow, the composition of the ejecta, as well as the collimation angle and the total energy budget. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1111.0283v2-abstract-full').style.display = 'none'; document.getElementById('1111.0283v2-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 March, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 November, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2011. </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 by ApJ</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg> <a href="https://info.arxiv.org/help/contact.html"> Contact</a> </li> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>subscribe to arXiv mailings</title><desc>Click here to subscribe</desc><path d="M476 3.2L12.5 270.6c-18.1 10.4-15.8 35.6 2.2 43.2L121 358.4l287.3-253.2c5.5-4.9 13.3 2.6 8.6 8.3L176 407v80.5c0 23.6 28.5 32.9 42.5 15.8L282 426l124.6 52.2c14.2 6 30.4-2.9 33-18.2l72-432C515 7.8 493.3-6.8 476 3.2z"/></svg> <a href="https://info.arxiv.org/help/subscribe"> Subscribe</a> </li> </ul> </div> </div> </div>   <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/license/index.html">Copyright</a></li> <li><a href="https://info.arxiv.org/help/policies/privacy_policy.html">Privacy Policy</a></li> </ul> </div> <div class="column sorry-app-links"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/web_accessibility.html">Web Accessibility Assistance</a></li> <li> <p class="help"> <a class="a11y-main-link" href="https://status.arxiv.org" target="_blank">arXiv Operational Status <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" class="icon filter-dark_grey" role="presentation"><path d="M224.3 273l-136 136c-9.4 9.4-24.6 9.4-33.9 0l-22.6-22.6c-9.4-9.4-9.4-24.6 0-33.9l96.4-96.4-96.4-96.4c-9.4-9.4-9.4-24.6 0-33.9L54.3 103c9.4-9.4 24.6-9.4 33.9 0l136 136c9.5 9.4 9.5 24.6.1 34z"/></svg></a><br> Get status notifications via <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/email/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg>email</a> or <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/slack/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" class="icon filter-black" role="presentation"><path d="M94.12 315.1c0 25.9-21.16 47.06-47.06 47.06S0 341 0 315.1c0-25.9 21.16-47.06 47.06-47.06h47.06v47.06zm23.72 0c0-25.9 21.16-47.06 47.06-47.06s47.06 21.16 47.06 47.06v117.84c0 25.9-21.16 47.06-47.06 47.06s-47.06-21.16-47.06-47.06V315.1zm47.06-188.98c-25.9 0-47.06-21.16-47.06-47.06S139 32 164.9 32s47.06 21.16 47.06 47.06v47.06H164.9zm0 23.72c25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06H47.06C21.16 243.96 0 222.8 0 196.9s21.16-47.06 47.06-47.06H164.9zm188.98 47.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06h-47.06V196.9zm-23.72 0c0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06V79.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06V196.9zM283.1 385.88c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06v-47.06h47.06zm0-23.72c-25.9 0-47.06-21.16-47.06-47.06 0-25.9 21.16-47.06 47.06-47.06h117.84c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06H283.1z"/></svg>slack</a> </p> </li> </ul> </div> </div> </div>  </div> </footer> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/member_acknowledgement.js"></script> </body> </html>

CINXE.COM

Search | arXiv e-print repository