Astrophysics and Space Science最新文献_第5页

Numerical simulation study of dispersive waves in presence of magnetic islands 磁岛存在下色散波的数值模拟研究

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-23 DOI: 10.1007/s10509-025-04453-4

Neha Pathak, Jyoti, Suresh C. Sharma, R. P. Sharma

引用次数: 0

Determination of Hubble constant from Megamaser Cosmology Project using profile likelihood 利用剖面似然法测定超级激光宇宙学计划中的哈勃常数

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-20 DOI: 10.1007/s10509-025-04454-3

Shubham Barua, Vyaas Ramakrishnan, Shantanu Desai

引用次数: 0

GNSS derived total electron content variation along the annularity path associated with O/N2 ratio change during the annular solar eclipse of 21 June 2020 GNSS推导了2020年6月21日日环食期间与O/N2比值变化相关的环径总电子含量变化

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-19 DOI: 10.1007/s10509-025-04452-5

A. K. Maurya, S. Saharan, S. Kannaujiya, M. N. Shrivastava, U. Pandey, H. Sharma

{"title":"GNSS derived total electron content variation along the annularity path associated with O/N2 ratio change during the annular solar eclipse of 21 June 2020","authors":"A. K. Maurya, S. Saharan, S. Kannaujiya, M. N. Shrivastava, U. Pandey, H. Sharma","doi":"10.1007/s10509-025-04452-5","DOIUrl":"10.1007/s10509-025-04452-5","url":null,"abstract":"<div><p>The present work focused on the low latitude ionospheric perturbation during the 21 June 2020 annular solar eclipse. The study is performed by using Global Navigation Satellite System (GNSS) derived total electron content (TEC) data from GNSS sites located across the annularity path. The annularity path was divided into four major regions: Africa, Arab, India and Taiwan, corresponding to morning, afternoon and evening local time. The GNSS sites are lying nearly the same eclipse magnitude/obscuration chosen for TEC analysis with two PRNs 06 & 19. The most remarkable finding is the presence of pre-eclipse enhancement in the TEC over the Indian region. The average change in TEC varies as ∼3.0-0.5 TECu (Total Electron Content Unit) during the morning (at Africa & Arab sites), ∼2.8 TECu during the afternoon (at Indian sites), and ∼3.5 TECu during the evening (at Taiwan sites). TEC derived from the COSMIC-2 satellite and global ionospheric maps (GIM) showed a maximum decrease in the evening and morning, while it was a minimum during the afternoon. The O/N<sub>2</sub> ratio from the GUVI payload onboard the TIMED satellite shows a significant increase of ∼12% on the eclipse day over the Indian region. Such thermosphere composition changes are suggested to be induced due to eclipse associated temperature change over the Tibetan plateau, which brought N<sub>2</sub> down and increased O/N<sub>2</sub> ratio, particularly over the Indian region. The enhanced O/N<sub>2</sub> ratio, in turn, enhances ionospheric electron density, thus explaining the pre-eclipse effect and minimum electron density change over the Indian region.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145167734","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}

引用次数: 0

Pressure anisotropy and magnetic field geometry in magnetorotational instability of Kerr black hole accretion disks 克尔黑洞吸积盘磁旋不稳定性中的压力各向异性和磁场几何

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-17 DOI: 10.1007/s10509-025-04451-6

Ji-Hoon Ha

{"title":"Pressure anisotropy and magnetic field geometry in magnetorotational instability of Kerr black hole accretion disks","authors":"Ji-Hoon Ha","doi":"10.1007/s10509-025-04451-6","DOIUrl":"10.1007/s10509-025-04451-6","url":null,"abstract":"<div><p>We formulate the dispersion relation for magnetorotational instability (MRI) in the accretion disk of a Kerr black hole, incorporating general relativistic effects and pressure anisotropy. By linearizing the general relativistic magnetohydrodynamic (GRMHD) equations in Boyer-Lindquist coordinates, we derive the MRI dispersion relation while explicitly accounting for frame-dragging effects, the gravitational potential, and the interaction between the magnetic field and the rotating plasma. Our analysis considers both toroidal and poloidal magnetic field components, allowing us to explore how different field geometries influence the MRI growth rate across three regimes corresponding to varying frame-dragging effects. The results show that the MRI growth rate is strongly influenced by plasma beta, pressure anisotropy, and the black hole spin parameter. Specifically, we find that pressure anisotropy alters the MRI dispersion relation by introducing additional instability criteria, which can either enhance or suppress MRI growth, depending on the alignment of the magnetic field components. These findings have important implications for electron acceleration in black hole accretion disks, as MRI-driven turbulence plays a key role in energy dissipation and particle energization. Our results provide a theoretical foundation for understanding plasma instabilities in relativistic accretion flows and their impact on high-energy astrophysical phenomena.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166440","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}

引用次数: 0

Reverberation responses in light curves of the SBS1520+530 quasar 类星体SBS1520+530光曲线的混响响应

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-17 DOI: 10.1007/s10509-025-04450-7

Liudmyla Berdina, Victoria Tsvetkova

{"title":"Reverberation responses in light curves of the SBS1520+530 quasar","authors":"Liudmyla Berdina, Victoria Tsvetkova","doi":"10.1007/s10509-025-04450-7","DOIUrl":"10.1007/s10509-025-04450-7","url":null,"abstract":"<div><p>We aim to investigate an accretion disk (AD) temperature profile of a doubly lensed quasar SBS 1520+530. Temperature profiles of accretion disks are known to be diagnostic of many of the physical properties of AGNs and quasars. Our approach involves application of the photometric reverberation mapping to the light curves of SBS 1520+530 obtained in the Johnson-Cousins <span>(V)</span> and <span>(R)</span> filters. The RM method implies that the time shift between the light curves taken in different spectral ranges determines the light travel time between the AD zones with different physical conditions. In determining the time shifts, we applied a method based on some useful properties of the orthogonal polynomials. The variations in filter <span>(R)</span> lag those in filter <span>(V)</span>, with 1.25±0.63 days for the inter-band time shift averaged between the two image components and over the three seasons. The obtained time lag noticeably exceeds the value following for SBS 1520+530 from the classical model of optically thick geometrically thin AD. We considered two possible ways to resolve the discrepancy between the theory and observations. The first assumes an AD temperature profile flatter than the classical one. The second way is to consider an extended optically thick scattering envelope originated due to matter outflow from an AD interior. Both explanations may be consequences of the super-Eddington accretion in SBS 1520+530. Using bolometric luminosity estimates available for SBS 1520+530 from the literature, we obtained a value of <span>(approx 3.4)</span> for the Eddington ratio, which indeed indicates a moderately super-Eddington accretion regime.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166441","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}

引用次数: 0

High-frequency Alfvén waves and energy transfer within accretion disks of neutron star merger remnants 中子星合并残余物吸积盘中高频alfvsamn波与能量转移

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-06 DOI: 10.1007/s10509-025-04448-1

Syeda Noureen

引用次数: 0

Can the cosmological (^{7}{mathrm{Li}}) problem be solved in the Weyl-type (f(Q,T)) modified gravity theory? 宇宙学(^{7}{mathrm{Li}})问题可以用weyl型(f(Q,T))修正引力理论来解决吗？

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-02 DOI: 10.1007/s10509-025-04446-3

Jian Ge, Lei Ming, Shi-Dong Liang, Hong-Hao Zhang, Tiberiu Harko

{"title":"Can the cosmological (^{7}{mathrm{Li}}) problem be solved in the Weyl-type (f(Q,T)) modified gravity theory?","authors":"Jian Ge, Lei Ming, Shi-Dong Liang, Hong-Hao Zhang, Tiberiu Harko","doi":"10.1007/s10509-025-04446-3","DOIUrl":"10.1007/s10509-025-04446-3","url":null,"abstract":"<div><p>One of the most powerful evidence for the Big Bang theory is the prediction of the primordial abundances of the elements by the Big Bang Nucleosynthesis (BBN) theory. The BBN theory in its standard formulation is a parameter-free theory, with the precise knowledge of the baryon-to-photon ratio of the Universe, obtained from studies of the anisotropies of cosmic microwave background radiation. The theoretical abundances of light elements during primordial nucleosynthesis and those determined from observations are in good agreement throughout a range of nine orders of magnitude. However, there is still a significant difference of the <sup>7</sup>Li abundance, overestimated by a factor of ∼ 2.5 when calculated theoretically. In the present work we will consider the nucleosynthesis process in the framework of the Weyl-type f(Q,T) theory, a modified gravity theory representing an extension of the f(Q) and f(Q,T) type theories, obtained under the assumption that the scalar non-metricity Q of the space-time is expressed in its standard Weyl form. Hence, the nonmetricity of the spacetime is fully determined by a vector field <span>(w^{mu })</span>. The theory can give a good description of the observational data, and of the evolution of the late-time Universe. We show that in some parameter ranges the Lithium abundance can be explained, and these ranges have a relatively weak dependence on the initial value of the Weyl vector.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-025-04446-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145160936","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}

引用次数: 0

Perihelion precession in non-Newtonian central potentials: addendum 非牛顿中心势的近日点进动：附录

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-02 DOI: 10.1007/s10509-025-04442-7

Michele Andreoli

引用次数: 0

Analyzing stellar and interstellar contributions to polarization: modeling approaches for hot stars 分析恒星和星际对极化的贡献：热恒星的建模方法

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-06-02 DOI: 10.1007/s10509-025-04445-4

Richard Ignace, Andrew G. Fullard, Georgia V. Panopoulou, D. John Hillier, Christiana Erba, Paul A. Scowen

{"title":"Analyzing stellar and interstellar contributions to polarization: modeling approaches for hot stars","authors":"Richard Ignace, Andrew G. Fullard, Georgia V. Panopoulou, D. John Hillier, Christiana Erba, Paul A. Scowen","doi":"10.1007/s10509-025-04445-4","DOIUrl":"10.1007/s10509-025-04445-4","url":null,"abstract":"<div><p>Linear polarimetry of unresolved stars is a powerful method for discerning or constraining the geometry of a source and its environment, since spherical sources produce no net polarization. However, a general challenge to interpreting intrinsic stellar polarization is the contribution to the signal by interstellar polarization (ISP). Here, we review methodologies for distinguishing the stellar signal from the interstellar contribution in the context of massive stars. We first characterize ISP with distance using a recent compilation of starlight polarization catalogs. Several scenarios involving Thomson scattering, rapidly rotating stars, optically thick winds, and interacting binaries are considered specifically to contrast the wavelength-dependent effects of ISP in the ultraviolet versus optical bands. ISP is recognizable in the stellar polarization from Thomson scattering in the polarization position angle rotations. For hot stars with near-critical rotation rates, the ISP declines whereas the stellar continuum polarization sharply increases. In the case of quite dense winds, strong ultraviolet lines trace the ISP, which is not always the case in the optical. In the binary case, temporal and chromatic effects illustrate how the ISP displaces variable polarization with wavelength. This study clarifies the impacts of ISP in relation to new ultraviolet spectropolarimetry efforts such as <i>Polstar</i> and <i>Pollux</i>.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145160937","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}

引用次数: 0

Revisiting the infrared/X-ray correlation of GX 339−4 based on a jet model 基于射流模型的GX 339−4红外/ x射线相关性研究

IF 1.8 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2025-05-30 DOI: 10.1007/s10509-025-04447-2

Chang-Yin Huang, Yi Xie

{"title":"Revisiting the infrared/X-ray correlation of GX 339−4 based on a jet model","authors":"Chang-Yin Huang, Yi Xie","doi":"10.1007/s10509-025-04447-2","DOIUrl":"10.1007/s10509-025-04447-2","url":null,"abstract":"<div><p>The infrared (IR)/X-ray correlation of GX 339−4 is investigated based on a jet model with a modification by linking the magnetic field at the jet base to the accretion rate of the inner accretion flow though the equilibrium between magnetic pressure at horizon and the ram pressure of the accretion flow. The IR flux is attributed to the synchrotron radiation of the jet, and the X-ray flux is attributed to the advective dominated accretion flow (ADAF), synchrotron radiation of the jet and synchrotron self-Compton scattering (SSC) of the jet, respectively. We find that the observed IR/X-ray correlation with a break is well reproduced with the variation of the accretion rate if the X-ray flux originates from SSC of the jet. Either a conical ballistic jet with the magnetic field parallel to the jet axis or a conical adiabatic jet with an isotropic field can account for the correlation. The power-law index of the energy distribution of electrons <span>(psim 3)</span>, the minimum Lorentz factor of the electrons <span>(gamma _{mathrm{min}}sim 60)</span>, the magnetic field <span>(B_{0}sim 10^{5} {mathrm{G}})</span> and the jet radius <span>(R_{0}sim 10^{10} {mathrm{cm}})</span> at the jet base are required for both the ballistic jet and the adiabatic jet. This study helps us clarify the complex interaction between the accretion and jet in GX 339−4, as well as the properties and geometric structure of the jet, laying the groundwork for exploring similar astrophysical systems.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171860","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}

引用次数: 0