Astronomische Nachrichten最新文献

{"title":"Magnetic Susceptibility of Relativistic Electrons in the Crust of Strongly Magnetized Neutron Stars","authors":"Zhi-Bing Li,&nbsp;Xin-Jun Zhao,&nbsp;Wei-Feng Zhang,&nbsp;Hui Wang","doi":"10.1002/asna.20250026","DOIUrl":"https://doi.org/10.1002/asna.20250026","url":null,"abstract":"<div>\u0000 \u0000 <p>Pulsars, characterized as highly magnetized and rapidly rotating neutron stars, offer a unique laboratory for probing physics under extreme conditions. Magnetars, a subclass of pulsars powered by magnetic field energy, exhibit quantized and highly degenerate Landau levels for relativistic electrons in their crustal ultrastrong magnetic fields. The energy difference between these Landau levels and the field-free system determines the magnetic susceptibility. We first review spin degrees of freedom in relativistic electrons and magnetization mechanisms, then employ quantum statistical methods to calculate the magnetic susceptibility of relativistic electron gases in magnetar crusts. Finally, numerical simulations for the paramagnetic susceptibility oscillatory in superhigh magnetic fields in the magnetar crust was performed. Our results reveal that the magnetization under ultrastrong fields demonstrates oscillatory behavior analogous to the de Haas–van Alphen effect observed in certain low-temperature metals. The total susceptibility, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>χ</mi>\u0000 </mrow>\u0000 <annotation>$$ chi $$</annotation>\u0000 </semantics></math>, comprises a non-oscillatory component (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>χ</mi>\u0000 <mi>m</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {chi}_m $$</annotation>\u0000 </semantics></math>) and an oscillatory term (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mover>\u0000 <mi>χ</mi>\u0000 <mo>˜</mo>\u0000 </mover>\u0000 <mi>m</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {tilde{chi}}_m $$</annotation>\u0000 </semantics></math>), where higher harmonic amplitudes of the oscillatory susceptibility grow with increasing electron density. Notably, the total paramagnetic susceptibility of electrons near the crust-core boundary does not exceed the critical magnetization threshold. However, if an ultrastrong magnetic field exists in the neutron star core, the susceptibility of the electron gas could surpass this critical value, suggesting the potential occurrence of non-equilibrium magnetization processes. This implies a first-order phase transition, akin to gas–liquid transitions, leading to coexisting stable magnetization states or metastable supercooled magnetic phases. A sudden transition from metastable to stable states may release stored magnetic energy, offering a plausible explanation for the observed excess radiation during magnetar giant flares.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135388","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":"On the Neutron Star Surface Thermal Radiation","authors":"Hui Wang,&nbsp;Zhi Fu Gao","doi":"10.1002/asna.20250031","DOIUrl":"https://doi.org/10.1002/asna.20250031","url":null,"abstract":"<div>\u0000 \u0000 <p>This review discusses the thermal evolution of neutron star crusts, focusing on recent advancements in cooling models, superfluidity, and surface composition. The cooling process primarily occurs through neutrino radiation and thermal conduction, with the surface temperature of young neutron stars remaining stable for about 100 years before the internal temperature gradually decreases. The paper also discusses challenges such as uncertainties in the equation of state and limited observational data. By bridging the gap between theoretical predictions and observational data, this review aims to deepen our understanding of the thermal evolution of neutron stars.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135391","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 Study for Mode Changing for Radio Pulsar J0742-2822 at 3.1 GHz","authors":"Jun Tan,&nbsp;Jia-Wei Wang,&nbsp;Cheng-Bing Lyu,&nbsp;Jin-Peng Wang,&nbsp;Hui Wang","doi":"10.1002/asna.20250032","DOIUrl":"https://doi.org/10.1002/asna.20250032","url":null,"abstract":"<div>\u0000 \u0000 <p>The mode switching of PSR J0742-2822 at 3.1 GHz was investigated using single-pulse data from the Parkes 64-m radio telescope in Australia. By analyzing the ratio of the relative intensity of the two components for each sub-integral profile, we classified the integral profile of this source into two modes: normal mode and abnormal mode. We then obtained the average profile of PSR J0742-2822 at 3.1 GHz for each mode. The results indicate that the normal and abnormal modes of integrated pulse profiles occurred 72% and 28% of the time, respectively, over a total of 3.7 h of observation. This study is significant for understanding the theoretical mechanism behind the pulsar mode-switching phenomenon.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135356","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 Properties of Fast Radio Bursts: A Short Review","authors":"Wen-Qi Ma,&nbsp;Zhi-Fu Gao","doi":"10.1002/asna.20250024","DOIUrl":"https://doi.org/10.1002/asna.20250024","url":null,"abstract":"<div>\u0000 \u0000 <p>Fast Radio Bursts (FRBs) are mysterious, short-duration bursts of radio waves originating from cosmological distance. This paper explores various properties of FRBs, such as Dispersion Measure (DM), Rotation Measure (RM), pulse width, duration, redshift distribution, and spectral index. The paper also introduces our recent research on FRB host galaxies and event rate density, focusing on recalculating event rate densities using sources discovered by CHIME/FRB. This review underscores the importance of continued research to unravel the mysteries of FRBs and their diverse properties.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135246","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":"Analysis of the Applicability of Deep Neural Networks on the Generalization of Neutron Star Equations of State","authors":"B. S. Gonçalves,&nbsp;M. Dutra,&nbsp;S. J. B. Duarte,&nbsp;B. Jardim,&nbsp;C. H. Lenzi","doi":"10.1002/asna.20250017","DOIUrl":"https://doi.org/10.1002/asna.20250017","url":null,"abstract":"<div>\u0000 \u0000 <p>The analysis of equations of state models, which describe the matter inside neutron stars, contributes to the understanding of two fundamental pillars of physics, nuclear matter and gravitation. Recent astrophysical observations such as the event titled GW170817, which founded the era of multi-messenger observations, as well as the important measurements established by the Neutron Star Interior Composition Explorer (NICER) of the radius and mass of the compact objects PSR J0030 + 0451 and PSR J0740 + 6620 brought new perspectives on the limitations and inconsistencies between observational data and predictions through the gravity model. Combining the current motivating scenario with the growth of available data and increased computational capacity, the topic has been expanded with the addition of new tools based on machine learning, which have evolved considerably since the mid-2010s. Seeking to contribute to the understanding through a simple and effective representation while maintaining robustness and reliability of its results among the range of complex models existing in the literature, the work under analysis focuses on the application of deep neural networks in the generalization of neutron star state equations, exploring the bases theories of generalized piecewise polytropic formalism, and the construction of a model whose learning method is based on Bayesian probability.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206686","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 Slow-Rotating Nucleus of Comet C/2013 R1 (Lovejoy)","authors":"Federico Manzini,&nbsp;Virginio Oldani,&nbsp;Andrea Farina,&nbsp;Paolo Ochner,&nbsp;Andrea Reguitti,&nbsp;Luigi R. Bedin,&nbsp;Jean Gabriel Bosch,&nbsp;Erik Bryssinck,&nbsp;Roberto Crippa,&nbsp;Stéphan Gaumont-Guay,&nbsp;Carl W. Hergenrother,&nbsp;Joel Nicolas,&nbsp;Ivo Scheggia","doi":"10.1002/asna.20240053","DOIUrl":"https://doi.org/10.1002/asna.20240053","url":null,"abstract":"<p>The close approach of comet C/2013 R1 (Lovejoy) allowed us to conduct an in-depth study of the morphology of the inner coma. From the measurement of the dust emission structures expanding near the cometary nucleus in November–December 2013, we derived a slow rotation period of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>47.8</mn>\u0000 <mo>±</mo>\u0000 <mn>1.2</mn>\u0000 </mrow>\u0000 <annotation>$$ 47.8pm 1.2 $$</annotation>\u0000 </semantics></math> h. The comet's spin axis is oriented approximately at RA = 332° and Dec = +47°. Numerical models of the inner coma suggest that its morphology was related to the presence of at least four main active sources located at different latitudes on the cometary nucleus, emitting dust of relatively small size and with variable velocity.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 5","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240053","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144482184","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":"Preliminary Study on Monitoring Local Atomic Clocks Using Millisecond Pulsars","authors":"Da-Lin He,&nbsp;Jian-Ping Yuan,&nbsp;Zhi-Gang Wen,&nbsp;Gao-Wen Sun,&nbsp;Wan-Li Ma,&nbsp;De-Jun Zhu,&nbsp;Hui Wang","doi":"10.1002/asna.20250023","DOIUrl":"https://doi.org/10.1002/asna.20250023","url":null,"abstract":"<div>\u0000 \u0000 <p>UTC(k) can be considered a shorthand for the local time standard maintained by a country's or region's time- frequency laboratory. Each lab uses its local atomic clocks to maintain this standard and synchronizes it with Coordinated Universal Time (UTC). Although local atomic clocks can operate independently, they generally rely on UTC as a reference standard for precision and long-term stability. To effectively monitor local atomic clocks and improve monitoring efficiency, this paper aims to study new monitoring methods from the perspective of macroscopic astrometry. By utilizing the measurement results of millisecond pulsars and combining them with clock models, this paper focuses on calculating and predicting the deviation data of local atomic clocks. This method not only expands the means of monitoring local atomic clocks but also has significant implications for improving monitoring accuracy and reliability. To validate its effectiveness, we first calculate and analyze the actual and simulated data of millisecond pulsars, then compare the analysis results with the conventional clock deviation data of local clocks based on UTC as a reference. The results indicate that using millisecond pulsars for monitoring can feasibly obtain the phase and frequency deviations of local atomic clocks within a 95% confidence interval. This demonstrates the feasibility of this method. Therefore, monitoring local atomic clocks using millisecond pulsars is reliable and effective. This study provides new insights and methods for the monitoring of local clocks and is significant for improving monitoring accuracy and reliability.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135220","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":"Anisotropy in Magnetized Quark Matter in the Chiral Limit","authors":"Sebastian Alberto Ferraris,&nbsp;Juan Pablo Carlomagno,&nbsp;Gustavo Anibal Gabriel Contrera,&nbsp;Ana Gabriela Grunfeld","doi":"10.1002/asna.20250020","DOIUrl":"https://doi.org/10.1002/asna.20250020","url":null,"abstract":"<div>\u0000 \u0000 <p>We investigate the behavior of cold quark matter under strong magnetic fields in the frame of a nonlocal NJL model in the chiral limit. Our analysis focuses on deconfinement, chiral symmetry restoration, and the anisotropy in pressure induced by the external magnetic field. For <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>eB</mi>\u0000 <mo>≲</mo>\u0000 <mn>0.07</mn>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mi>GeV</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ eBlesssim 0.07kern0.22em {mathrm{GeV}}^2 $$</annotation>\u0000 </semantics></math>, the critical chemical potential remains largely insensitive to the magnetic field, whereas at higher field strengths, transitions to chirally restored phases occur at progressively lower chemical potentials. The parallel and perpendicular pressures, with respect to the magnetic field, exhibit distinct behaviors, reflecting the anisotropic nature of the system. Oscillations in the quark number density, driven by the de Haas–van Alphen effect, reflect the quantized behavior of quarks in a magnetic field. Similarly, the magnetization displays oscillatory behavior, driven by the sequential filling of Landau levels (LLs). At lower external magnetic field strengths, contributions from orbital angular momentum and the population of higher LLs further modulate these oscillations. These results provide deeper insights into the thermodynamic and magnetic properties of quark matter under strong magnetic fields, with implications for astrophysical studies.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144207083","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 Multi-Wavelength Spectral Energy Distribution of NGC 315","authors":"Jianchao Feng,&nbsp;Cong Ran,&nbsp;Qian Peng,&nbsp;Ai-Jun Dong","doi":"10.1002/asna.20250015","DOIUrl":"https://doi.org/10.1002/asna.20250015","url":null,"abstract":"<div>\u0000 \u0000 <p>The majority of nearby low-luminosity active galactic nuclei (LLAGNs), are widely found in compact radio cores and/or weak jets. The central of galaxy is believed to be powered by hot accretion flow and jet. Besides the famous LLAGN sources M87 and Sgr A*, NGC 315 is also a well-known supermassive black hole (SMBH), which can be used to explore accretion and jet physics. The aim of this work is to model the multi-wavelength spectral energy distribution (SED) of the NGC 315, and all the data we used here in the literature correspond to the core emission. Similarly to M87 and Sgr A*, we find that the SED is hard to fit with a pure jet model or pure advection-dominated accretion flow (ADAF). And with a coupled ADAF-jet model, we find that the low-frequency radio emission is better fitted by the synchrotron radiation of nonthermal electrons in the jet, and high-frequency radio emission is mainly consistent with the inverse Compton radiation from electrons in ADAF. Furthermore, the high-energy X-ray emission can also be simultaneously explained by ADAF. From the SED fitting, we obtain important parameters of the central engine, we find that the SMBH in NGC 315 should be fast rotating with a dimensionless spin parameter <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>a</mi>\u0000 <mo>*</mo>\u0000 </msub>\u0000 <mo>≃</mo>\u0000 <mn>0.9</mn>\u0000 </mrow>\u0000 <annotation>$$ {a}_{ast}simeq 0.9 $$</annotation>\u0000 </semantics></math>, and only a small fraction of the material captured at the outer radius reaches the SMBH. These results will help us better understand the accretion and jet physics. And future further simultaneous multi-wavelength observations will help us to better understand these questions.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135739","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. 2/2025","authors":"","doi":"10.1002/asna.20259002","DOIUrl":"https://doi.org/10.1002/asna.20259002","url":null,"abstract":"","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 2","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20259002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489687","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}