Astronomische Nachrichten最新文献

{"title":"Pulsed and Polarized X-Ray Emission From Neutron Star Surfaces","authors":"Matthew G. Baring,&nbsp;Hoa Dinh Thi,&nbsp;George A. Younes,&nbsp;Kun Hu","doi":"10.1002/asna.20240104","DOIUrl":"https://doi.org/10.1002/asna.20240104","url":null,"abstract":"<div>\u0000 \u0000 <p>The intense magnetic fields of neutron stars naturally lead to strong anisotropy and polarization of radiation emanating from their surfaces, both being sensitive to the hot spot position on the surface. Accordingly, pulse phase-resolved intensities and polarizations depend on the angle between the magnetic and spin axes and the observer's viewing direction. In this paper, results are presented from a Monte Carlo simulation of neutron star atmospheres that uses a complex electric field vector formalism to treat polarized radiative transfer due to magnetic Thomson scattering. General relativistic influences on the propagation of light from the stellar surface to a distant observer are taken into account. The paper outlines a range of theoretical predictions for pulse profiles at different X-ray energies, focusing on magnetars and also neutron stars of lower magnetization. By comparing these models with observed intensity and polarization pulse profiles for the magnetar 1RXS J1708-40, and the light curve for the pulsar PSR J0821-4300, constraints on the stellar geometry angles and the size of putative polar cap hot spots are obtained.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143116203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Crucial Discovery of Thermonuclear X-Ray Bursts: Never Throw Away Old Data!","authors":"Erik Kuulkers","doi":"10.1002/asna.20240108","DOIUrl":"https://doi.org/10.1002/asna.20240108","url":null,"abstract":"<div>\u0000 \u0000 <p>The discovery of Type I x-ray bursts is attributed to those seen by the Astronomical Netherlands Satellite (ANS) in September 1975 from the globular cluster NGC 6624 containing the x-ray source 4U 1820-303. I revisit these x-ray bursts, by reanalyzing data from the Soft X-ray Experiment (SXX) onboard ANS, which were stored on microfiche. Earlier accounts of x-ray bursts had been reported; the first Type I x-ray burst recorded is the one observed by Vela 5B from Cen X-4 in July 1969.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143116192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beyond Accretion Limits: The Rise of Pulsating Gems","authors":"Gian Luca Israel,&nbsp;Roberta Amato,&nbsp;Matteo Imbrogno,&nbsp;Nicoló Oreste Pinciroli Vago,&nbsp;a Larger Team","doi":"10.1002/asna.20240102","DOIUrl":"https://doi.org/10.1002/asna.20240102","url":null,"abstract":"<p>The discovery of several ultraluminous X-ray sources exhibiting fast and rapidly evolving X-ray pulsations unequivocally associates these sources with accreting neutron stars orbiting relatively massive companion stars (&gt; 8M<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mo> </mo>\u0000 <mo>⊙</mo>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {}_{odot } $$</annotation>\u0000 </semantics></math>). Among these ULXs, the brightest pulsating ULX (PULX), NGC 5907 ULX-1, displays a peak luminosity (~2 × 10⁴¹ erg s⁻¹) that exceeds its Eddington limit by ~1000 times. These discoveries have raised several key questions, the most urgent of which include: what physical process (or processes) is driving the observed luminosities? What is the nature of compact objects in the still non-pulsating ULXs, and how can we unambiguously ascertain it? Why are PULXs so rare and elusive, and how can we identify more members of this class? In this contribution, a brief overview of the ULX class is provided focusing on PULXs, presenting the most recent results obtained for NGC 5907 ULX-1, NGC 7793 P13, M82 X-2 and M51 ULX-7. How current-generation X-ray missions are already providing (and can continue to do so in the next years) a wealth of information to address the aforementioned questions is also outlined.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240102","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Brief, Biased View of Neutron Star Cooling","authors":"Craig Heinke","doi":"10.1002/asna.20240110","DOIUrl":"https://doi.org/10.1002/asna.20240110","url":null,"abstract":"<p>This is a concise and non-technical review of topics related to neutron star (NS) cooling, for both young NSs and NSs in low-mass x-ray binaries. Neutrino emission from the NS core drives cooling rates, via different processes including Urca processes and pair breaking and formation at the neutron superfluid critical temperature. Key insights have been given by the temperatures of the coldest NSs, by the rapid (questioned) cooling of the Cas A NS, and by measuring the cooling of transient NS x-ray binaries after accretion episodes.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240110","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Analytical Model for Transit Light Curves","authors":"Dorin Drignei","doi":"10.1002/asna.20240078","DOIUrl":"https://doi.org/10.1002/asna.20240078","url":null,"abstract":"<div>\u0000 \u0000 <p>Transits and secondary eclipses of an exoplanet orbiting a host star generate dips in the light curve. This article proposes a new class of mathematical functions that provide simple and computationally efficient models for such light curves. The transit and secondary eclipse functions account for ingress/egress, and the transit function incorporates curvilinear limb darkening. Their parameters are estimated using least squares methods. These models can be used to test for the statistical significance of dips, potentially revealing the existence of an exoplanet. In addition, they can be used to estimate features such as duration and depth of a transit or a secondary eclipse, limb darkening curvature and ingress/egress slope, and the orbital period. Examples using publicly available light curve data are presented, demonstrating the accuracy and efficiency of the proposed functions as fast analytical models for transits and/or secondary eclipses.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143187047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"XMM-Newton Observations of the Peculiar Be X-Ray Binary A0538-66","authors":"Michela Rigoselli,&nbsp;Caterina Tresoldi,&nbsp;Lorenzo Ducci,&nbsp;Sandro Mereghetti","doi":"10.1002/asna.20240098","DOIUrl":"https://doi.org/10.1002/asna.20240098","url":null,"abstract":"<p>A0538-66 is a neutron star/Be x-ray binary located in the Large Magellanic Cloud and, since its discovery in the 70s, it showed a peculiar behavior that makes it a unique object in the high-mass x-ray binaries scene: the extremely eccentric orbit (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>e</mi>\u0000 <mo>=</mo>\u0000 <mn>0.72</mn>\u0000 </mrow>\u0000 <annotation>$$ e=0.72 $$</annotation>\u0000 </semantics></math>), the short spin period of the neutron star (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>P</mi>\u0000 <mo>=</mo>\u0000 <mn>69</mn>\u0000 </mrow>\u0000 <annotation>$$ P=69 $$</annotation>\u0000 </semantics></math> ms), the episodes of super-Eddington accretion. These characteristics contribute to a remarkable bursting activity that lasts from minutes to hours and increases the flux by a factor <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>3</mn>\u0000 </msup>\u0000 <mo>−</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>4</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ {10}^3-{10}^4 $$</annotation>\u0000 </semantics></math>. In 2018, A0538-66 was observed by <i>XMM-Newton</i> in a particularly active state, characterized by a forest of short bursts lasting <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>0.7</mn>\u0000 <mo>−</mo>\u0000 <mn>50</mn>\u0000 </mrow>\u0000 <annotation>$$ 0.7-50 $$</annotation>\u0000 </semantics></math> s each. In this contribution, we present a reanalysis of these observations. The timing analysis allowed us to distinguish between the epochs of direct accretion and propeller state that do not correlate with the orbital position of the neutron star. The spectral analysis revealed that during the accretion regime, three components (a soft one, a hard one, and a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>6.4</mn>\u0000 </mrow>\u0000 <annotation>$$ sim 6.4 $$</annotation>\u0000 </semantics></math>-keV emission line) equally contribute to the overall emission, while the propeller regime is characterized by a single soft component. We discuss these findings in the context of spherical and disk accretion regimes, highlighting the similarities and differences with other x-ray binary systems.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240098","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INTEGRAL Observations of Magnetars","authors":"Dominik Patryk Pacholski,&nbsp;Lorenzo Ducci,&nbsp;Martin Topinka,&nbsp;Sandro Mereghetti","doi":"10.1002/asna.20240109","DOIUrl":"https://doi.org/10.1002/asna.20240109","url":null,"abstract":"<p>The INTEGRAL satellite has collected a large amount of data on magnetars in our Galaxy, spanning more than 20 years starting from 2003. The large data set obtained with the IBIS/ISGRI instrument at energies above 20 keV allows us to study both the properties and long-term evolution of their persistent hard X-ray emission and the population characteristics of the short bursts emitted during active periods. We are carrying out a comprehensive analysis of the observed magnetars, exploiting the most recent calibrations and analysis software. Here we report on the long term evolution of the hard X-ray flux of the magnetars detected with ISGRI and the results of a sensitive search for short bursts in SGR J1935+2154.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240109","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of XMM–Newton in the Investigation of Persistent BeXRBs","authors":"Nicola La Palombara,&nbsp;Lara Sidoli,&nbsp;Sandro Mereghetti,&nbsp;Gian Luca Israel,&nbsp;Paolo Esposito","doi":"10.1002/asna.20240100","DOIUrl":"https://doi.org/10.1002/asna.20240100","url":null,"abstract":"<p>The persistent BeXRBs are a class of high-mass X-ray binaries (HMXRBs), which are characterized by persistent low X-ray luminosities (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mi>X</mi>\u0000 </msub>\u0000 <mo>~</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>34</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ {L}_{mathrm{X}}sim {10}^{34} $$</annotation>\u0000 </semantics></math> erg s<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mo> </mo>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ {}^{-1} $$</annotation>\u0000 </semantics></math>) and wide (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>P</mi>\u0000 <mi>orb</mi>\u0000 </msub>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation>$$ {P}_{mathrm{orb}}&gt; $$</annotation>\u0000 </semantics></math> 30 days), almost circular orbits. In these sources the NS is slowly rotating (with <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>P</mi>\u0000 <mtext>spin</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {P}_{mathrm{spin}} $$</annotation>\u0000 </semantics></math> well above 100 s) and accretes matter directly from the wind of the companion Be star, without the formation of an accretion disk. Since the '90s, when the first four members of this class were identified, several other sources of the same type have been discovered and investigated. Thanks to follow-up <i>XMM-Newton</i> observations, we have verified that most of them share common spectral and timing properties, such as a pulsed fraction that does not vary with the photon energy and a hot (kT = 1–2 keV) blackbody spectral component which contributes for 20%–40% to the total flux and has a size consistent with the NS polar cap. Here we provide an overview of how <i>XMM-Newton</i> contributed to constrain the observational properties and the current understanding of this type of sources. We also report about the first results obtained with a very recent <i>XMM-Newton</i> observation of the poorly known BeXRB 4U 0728-25.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240100","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scales of Stability and Turbulence in the Molecular ISM","authors":"Eric Keto","doi":"10.1002/asna.20240044","DOIUrl":"https://doi.org/10.1002/asna.20240044","url":null,"abstract":"<div>\u0000 \u0000 <p>We reanalyze the data of the BU-FCRAO <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 <mo> </mo>\u0000 </mrow>\u0000 <mn>13</mn>\u0000 </msup>\u0000 <mi>CO</mi>\u0000 </mrow>\u0000 <annotation>$$ {}^{13}mathrm{CO} $$</annotation>\u0000 </semantics></math> Galactic Ring Survey (GRS) to understand the dynamics of the turbulent molecular interstellar medium. We define molecular clouds by their spatial half-power contours of ¹³CO-integrated intensity, independent of a boundary based on thresholding or tiling. We find properties of hydrostatic equilibrium (HE) and virial equilibrium (VE), the former independent and the latter dependent on time and spatial scales. We suggest that HE is a stationary property of the turbulence and that molecular clouds are high-density regions of a fluctuating component. The gravitational and turbulent kinetic energies within clouds are continuously evolving toward a time-dependent VE with the fluctuating, external, turbulent pressure energy (PE) that can be treated parametrically owing to the shorter time scale for virialization. The average PE is comparable to the pressure of the multiphase ISM at the Galactic mid-plane. Larson's scaling relations analyzed by different statistical methods are not significant. The nondimensional variances of size, line width, and column density are of comparable magnitude, ruling out the inference of constant column density. Previously unrecognized autocorrelations may have contributed to the apparent validity of the inference.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143186326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting the Intrabinary Shock Model for Millisecond Pulsar Binaries: Radiative Losses and Long-Term Variability","authors":"Jaegeun Park,&nbsp;Chanho Kim,&nbsp;Hongjun An,&nbsp;Zorawar Wadiasingh","doi":"10.1002/asna.20240099","DOIUrl":"https://doi.org/10.1002/asna.20240099","url":null,"abstract":"<div>\u0000 \u0000 <p>Spectrally hard x-ray emission with double-peak light curves (LCs) and orbitally modulated gamma rays have been observed in some millisecond pulsar binaries, phenomena attributed to intrabinary shocks (IBSs). While the existing IBS model by Sim et al. (2024; <i>Astrophysical Journal</i> 964(2):109) successfully explains these high-energy features observed in three pulsar binaries, it neglects particle energy loss within the shock region. We refine this IBS model to incorporate radiative losses of x-ray emitting electrons and positrons and verify that the losses have insignificant impact on the observed LCs and spectra of the three binaries. Applying our refined IBS model to the x-ray bright pulsar binary PSR J1723-2837, we predict that it can be detected by the Cherenkov Telescope Array. Additionally, we propose that the long-term x-ray variability observed in XSS J12270-4859 and PSR J1723-2837 is due to changes in the shape of their IBSs. Our modeling of the x-ray variability suggests that these IBS shape changes may alter the extinction of the companion's optical emission, potentially explaining the simultaneous optical and x-ray variability observed in XSS J12270-4859. We present the model results and discuss their implications.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}