Astronomische Nachrichten最新文献

{"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}

{"title":"Correlation Between Radio Loudness and the Eddington Ratio in Quasars","authors":"Jing-Jing Shen,&nbsp;Xiang-Tao Zeng,&nbsp;Wei-Rong Huang,&nbsp;Ze-Yuan Tang,&nbsp;Jun-Hui Fan","doi":"10.1002/asna.20240072","DOIUrl":"https://doi.org/10.1002/asna.20240072","url":null,"abstract":"<div>\u0000 \u0000 <p>Quasars can be categorized into radio-loud and radio-quiet populations based on radio properties. The physical mechanisms underlying this dichotomy have long been an active area of investigation. In this work, we analyze multi-wavelength data from 851 quasars matched between the SDSS DR14 and FIRST catalogs, requiring emission line measurements with signal-to-noise ratios &gt; 3, we fit quasar optical continuum spectra and compute the radio loudness, luminosities, and Eddington ratios. We classify quasars as radio-loud or radio-quiet using a dividing line of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>log</mi>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mrow>\u0000 <mn>6</mn>\u0000 <mi>cm</mi>\u0000 </mrow>\u0000 </msub>\u0000 <mo>=</mo>\u0000 <mo>−</mo>\u0000 <mn>2.7</mn>\u0000 <mi>log</mi>\u0000 <mi>R</mi>\u0000 <mo>+</mo>\u0000 <mn>44.3</mn>\u0000 </mrow>\u0000 <annotation>$$ log {L}_{6mathrm{cm}}=-2.7log R+44.3 $$</annotation>\u0000 </semantics></math>. We find that the distribution of the Eddington ratio and radio luminosity is different between the radio-loud and radio-quiet quasars, and the correlation between the Eddington ratio and radio loudness is disparate as well. The Eddington ratio shows a weakly positive correlation with radio loudness in both the whole sample and radio-loud quasars, which imply that the Eddington ratio contributes to the radio loudness but it is not the dominant factor and that additional factors influence relativistic jet production in radio-loud quasars. However, the Eddington ratio is anti-correlated with radio loudness in radio-quiet quasars, potentially related to the properties of the accretion disk.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143186332","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":"Editor's Note: The X-Ray Mysteries of Neutron Stars and White Dwarfs","authors":"Norbert Schartel","doi":"10.1002/asna.20240093","DOIUrl":"https://doi.org/10.1002/asna.20240093","url":null,"abstract":"","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120180","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":"Probing the Propeller Regime With Wide Neutron Star Binaries","authors":"M. D. Afonina,&nbsp;S. B. Popov","doi":"10.1002/asna.20240096","DOIUrl":"https://doi.org/10.1002/asna.20240096","url":null,"abstract":"<div>\u0000 \u0000 <p>We model the duration of the propeller stage in wide binary systems with neutron stars and calculate the time of accretion onset for various propeller models. We apply our modeling to the symbiotic X-ray binary SWIFT J0850.8-4219. Unless a propeller with a very slow spin-down is operating, it is very improbable to find a system similar to SWIFT J0850.8-4219 at the propeller stage. Then we model the evolution of a neutron star in a binary with a solar-like companion. We calculate for which orbital separations and magnetic fields a neutron star can start to accrete while the companion is still on the Main sequence. We demonstrate that for the magnetic field <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>B</mi>\u0000 <mo>≲</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>12</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ Blesssim {10}^{12} $$</annotation>\u0000 </semantics></math> G neutron stars at the orbital separation <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>a</mi>\u0000 <mo>≳</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 <annotation>$$ agtrsim 1 $$</annotation>\u0000 </semantics></math> AU do not reach the propeller stage. In the case of a slow propeller spin-down, neutron stars never start to accrete. For the more rapid propeller spin-down, a neutron star can start to accrete or spend a long time at the propeller stage depending on the parameters.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120179","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 Effects of a Minimal Length on the Kerr Metric and the Hawking Temperature","authors":"Peter O. Hess,&nbsp;Leila Maghlaoui","doi":"10.1002/asna.20240092","DOIUrl":"https://doi.org/10.1002/asna.20240092","url":null,"abstract":"<div>\u0000 \u0000 <p>We first resume the main properties of the pseudo-complex General Relativity (pcGR). We show that the pcGR includes a generalized Mach's principle, namely that mass not only curved space–time but also changes vacuum properties. Then the Hawking temperature is determined within pcGR for a black hole, with varying the intensity of the dark energy around the central mass. In particular we investigate the effects of a minimal length, which is a consequence of pcGR. Three cases are studied: (i) The pc-Schwarzschild case with zero minimal length; (ii) The pc-Kerr case with zero minimal length; and finaly (iii) the pc-Kerr-case with a minimal length. We show that Hawking radiation can also be emitted in a curved space (the gravitational Schwinger effect), not necessarily at the surface of a star. When an event horizon is present, the theory predicts the occurrence of negative temperature, which generate negative pressure, stabilizing the star in this manner. We also show that the effects of a minimal length are only noticeable for very small black hole masses, showing that their formation is inhibited.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144207102","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":"Issue Information: Astron. Nachr. 07/2024","authors":"","doi":"10.1002/asna.20249007","DOIUrl":"https://doi.org/10.1002/asna.20249007","url":null,"abstract":"","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 8","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20249007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443503","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":"Cover Picture: Astron. Nachr. 8/2024","authors":"Hikmet Çakmak,&nbsp;Talar Yontan,&nbsp;Selçuk Bilir,&nbsp;Timothy S. Banks,&nbsp;Raúl Michel,&nbsp;Esin Soydugan,&nbsp;Seliz Koç,&nbsp;Hülya Erçay","doi":"10.1002/asna.20249016","DOIUrl":"https://doi.org/10.1002/asna.20249016","url":null,"abstract":"<p>Vector-Point Diagrams (left panels) and proper-motion component vectors (right panels) for identified member stars in the open clusters Ruprecht 1 and Ruprecht 171. These two previously little-studied open clusters, both at a distance of approximately 1.5 kpc, have been characterized and studied in some detail in the related paper by Çakmak and collaborators, published in this issue e240054.\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 8","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20249016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443544","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":"Denoising Medium Resolution Stellar Spectra With Neural Networks","authors":"Balázs Pál,&nbsp;László Dobos","doi":"10.1002/asna.20240049","DOIUrl":"https://doi.org/10.1002/asna.20240049","url":null,"abstract":"<div>\u0000 \u0000 <p>We trained denoiser autoencoding neural networks on medium resolution simulated optical spectra of late-type stars to demonstrate that the reconstruction of the original flux is possible at a typical relative error of a fraction of a percent down to a typical signal-to-noise ratio of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>10</mn>\u0000 </mrow>\u0000 <annotation>$$ 10 $$</annotation>\u0000 </semantics></math> per pixel. We show that relatively simple networks are capable of learning the characteristics of stellar spectra while still flexible enough to adapt to different values of extinction and fluxing imperfections that modifies the overall shape of the continuum, as well as to different values of Doppler shift. Denoised spectra can be used to find initial values for traditional stellar template fitting algorithms and—since evaluation of pretrained neural networks is significantly faster than traditional template fitting—denoiser networks can be useful when a fast analysis of the noisy spectrum is necessary, for example during observations, between individual exposures.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143187007","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":"HX Velorum: Ellipsoidal/Rotational Binary With β Cep Type Component","authors":"B. Gürol","doi":"10.1002/asna.20240028","DOIUrl":"https://doi.org/10.1002/asna.20240028","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;We present the Transiting Exoplanet Survey Satellite (TESS) light curve analysis of HX Velorum, located in the Southern Hemisphere, where one of the components is found for the first time to be a &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;β&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ beta $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; Cep (BCEP) type pulsator. The TESS observations of HX Velorum were published in a total of 6 sectors. Fourier analysis of the observations reveals that the frequencies can be divided into two categories, one of which is related to the orbital period and the other related to the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;β&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ beta $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; Cep-type pulsation. Its non-eclipsing light curve was analyzed with the well-known Wilson–Devinney code, and we obtained the geometric and physical parameters of the components using published radial velocity and light curve data by making some assumptions. We obtained plausible masses and radii of the primary and secondary components as &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;9.48&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.27&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;mo&gt;⊙&lt;/mo&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {M}_1=9.48pm 0.27{M}_{odot } $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;5.92&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.17&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;mo&gt;⊙&lt;/mo&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {M}_2=5.92pm 0.17{M}_{odot } $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;3.93&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.04&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mo&gt;⊙&lt;/mo&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {R}_1=3.93pm 0.04{R}_{odot } $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 ","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 8","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443557","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":"Red Quasars: Estimation of SMBH Spin, Mass, and Accretion Disk Inclination Angle","authors":"M. Yu. Piotrovich,&nbsp;S. D. Buliga,&nbsp;T. M. Natsvlishvili","doi":"10.1002/asna.20240058","DOIUrl":"https://doi.org/10.1002/asna.20240058","url":null,"abstract":"<div>\u0000 \u0000 <p>We estimated values of spin, mass, and inclination angle for sample of 42 red quasars. Our estimations show that two objects: F2MS J1113+1244 and F2MS J1434+0935 with the highest Eddington ratios may have geometrically thick disk. Six objects: SDSS J0036-0113, S82X 0040+0058, S82X 0118+0018, S82X 0303-0115, FBQS J1227+3214, S82X 2328-0028 may have “retrograde” rotation. Analysis of estimated spin values shows that red quasar population may contain Seyfert galaxies and NLS1.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 8","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443411","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}