Astrophysics and Space Science最新文献

{"title":"Investigation of states switch properties of PSR J1946 + 1805 with the FAST","authors":"Jie Tian,&nbsp;Xin Xu,&nbsp;Juntao Bai,&nbsp;Jiguang Lu,&nbsp;Lunhua Shang,&nbsp;Shi Dai,&nbsp;Dandan Zhang,&nbsp;Guojun Qiao,&nbsp;Rushang Zhao,&nbsp;Aijun Dong,&nbsp;Wenqian Zhong,&nbsp;Qijun Zhi,&nbsp;Shijun Dang","doi":"10.1007/s10509-024-04284-9","DOIUrl":"10.1007/s10509-024-04284-9","url":null,"abstract":"<div><p>We have carried out a detailed study of the single pulse of PSR J1946 + 1805 with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We reassessed the nulling fraction (NF) to be 57.5%. We also reverted the multiple drifting modes and obtained their drifting parameters. It is found that, for this pulsar, there exists the dwarf pulse at the beginning or end of the burst state, and the duration of dwarf pulse usually is one to two pulse periods. Additionally, we observed that there are scattered dwarf pulses detected in the null state. Detailed analysis of the fraction of linear polarization for all dwarf pulse is presented. It is worth noting that relative to normal pulses these dwarf pulses have a very high fraction of linear polarization, even more than 90%. We proposed that the dwarf pulses appearing at the beginning or end of the burst state may be a common behavior, which is important to understand the physical mechanism of the process of switching between two states.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139918590","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":"Collision properties of overtaking magnetosonic solitary waves in the ionospheric multi-ion plasmas","authors":"Dong-Ning Gao,&nbsp;Heng Zhang,&nbsp;Zhong-Zheng Li","doi":"10.1007/s10509-024-04278-7","DOIUrl":"10.1007/s10509-024-04278-7","url":null,"abstract":"<div><p>We study the magnetosonic waves (MWs) propagating in magnetized plasmas comprising light warm ions, cold heavy ions and hot electrons at the Earth’s ionosphere. The dispersion relation is given and the effects of different physical parameters on the frequency of fast and slow MSWs are shown. We derive a KdV equation for the MSWs in multi-ion plasma and study the two-soliton and three-soliton overtaking collision of KdV MSWs by Hirota’s bilinear method. We show the trajectories and amplitude of solitons in this process, and the phase shift after collision. It is found that when solitons merge, it will form a new soliton whose amplitude first decreases then increases. The effects of physical parameters on the phase shift of multi-soliton collision are presented. It is worth noting that the solitons’ interaction can result in the redistribution of momentum and energy in the plasmas.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139756276","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":"New class of anisotropic charged strange quark star in Durgapal (IV) metric and its maximum mass","authors":"S. Sarkar,&nbsp;D. Bhattacharjee,&nbsp;K. B. Goswami,&nbsp;P. K. Chattopadhyay","doi":"10.1007/s10509-024-04283-w","DOIUrl":"10.1007/s10509-024-04283-w","url":null,"abstract":"<div><p>In this paper, we have explored the relativistic stellar model considering pressure anisotropy. An anisotropic solution of the Einstein Field Equations (henceforth EFE) has been presented for charged strange quark stars considering the interior space-time geometry described by the Durgapal <span>(IV^{th})</span> metric. In the case of a strange quark star, if the equation of state <span>(p_{r}=frac{1}{3}(rho -4B_{g}))</span> as prescribed in the MIT bag model is applicable, then at the surface, one may consider that the surface energy density <span>(rho _{s}=4B_{g})</span>. Imposing the constraint value of <span>(B_{g})</span> within the range of 57.55 - <span>(95.11~MeV/fm^{3})</span> required for stable quark matter with respect to a neutron when the external pressure is zero, we have determined the maximum mass and radius of the strange quark star and other relevant properties. It is noted that the maximum mass and radius for <span>(B_{g}=57.55~MeV/fm^{3})</span> are <span>(M_{max}=2.92M_{odot })</span> and <span>(b_{max}=13.749~km)</span>, respectively, whereas those for <span>(B_{g}=95.11~MeV/fm^{3})</span>, are <span>(M_{max}=2.27M_{odot })</span> and <span>(b_{max}=10.695~km)</span> for an isotropic uncharged star. In the presence of pressure anisotropy and charge, the value of maximum mass increases. We have predicted the radii of a few recently observed pulsars from our model and found that the radii agree with the predictions from observations. Furthermore, stability and energy conditions are also satisfied in the present model.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139690007","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":"Multi-wavelength observation of MAXI J1348–630 during the outburst in 2019","authors":"Manoj Mandal,&nbsp;Debasish Saha,&nbsp;Sabyasachi Pal,&nbsp;Arijit Manna","doi":"10.1007/s10509-024-04280-z","DOIUrl":"10.1007/s10509-024-04280-z","url":null,"abstract":"<div><p>We study the multi-wavelength spectral properties of the black hole X-ray binary MAXI J1348–630 using quasi-simultaneous <i>ALMA</i>, <i>NICER</i>, and <i>Swift</i> observations during the decay phase of the January 2019 outburst. In millimeter wavelengths, radio continuum emissions in the frequency range of 89.56–351.44 GHz are measured. We found that the flux densities at millimeter wavelength varied between 12.18 mJy and 18.47 mJy with spectral index (<span>(alpha )</span>) of <span>(0.28pm 0.02)</span>. The broadband spectrum suggests that the source was accompanied by weak synchrotron emission from the compact jets. Broadband spectral study indicates that MAXI J1348–630 falls in the regime of “radio-quiet” during the decay phase of the outburst. The <i>NICER</i> spectrum is fitted by a combined model of disk blackbody component (<i>diskbb</i>) along with a comptonization component (<i>simpl</i>) which explains the power-law continuum caused by the thermal Comptonisation of soft disk photons in a hot gas of electrons. The <i>NICER</i> spectrum is dominated by the comptonised components during the decay phase of the outburst close to the hard state of the source. We have investigated the correlation between X-ray and radio luminosity using quasi-simultaneous <i>ALMA</i> and <i>NICER</i> data to understand the source nature by locating the source in the <span>(L_{X})</span>-<span>(L_{R})</span> diagram. The correlation study of radio/X-ray luminosity suggests that MAXI J1348–630 did not follow the well-known track for black holes and it is a new member of a restricted group of sources.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139690264","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":"Dark energy constraints from Pantheon+ Ia supernovae data","authors":"Sergio Torres-Arzayus","doi":"10.1007/s10509-024-04282-x","DOIUrl":"10.1007/s10509-024-04282-x","url":null,"abstract":"<div><p>Measurements of the current expansion rate of the Universe, <span>(H_{0})</span>, using standard candles, disagree with those derived from observations of the Cosmic Microwave Background (CMB). This discrepancy, known as the <i>Hubble tension</i>, is substantial and suggests the possibility of revisions to the standard cosmological model (Cosmological constant <span>(Lambda )</span> and cold dark matter – <span>(Lambda CDM)</span>). Dynamic dark energy (DE) models that introduce deviations in the expansion history relative to <span>(Lambda CDM)</span> could potentially explain this tension. We used Type Ia supernovae (SNe) data to test a dynamic DE model consisting of an equation of state that varies linearly with the cosmological scale factor <span>(a)</span>. To evaluate this model, we developed a new statistic (the <span>(T_{alpha })</span> statistic) used in conjunction with an optimization code that minimizes its value to obtain model parameters. The <span>(T_{alpha })</span> statistic reduces bias errors (in comparison to the <span>(chi ^{2})</span> statistic) because it retains the sign of the residuals, which is meaningful in testing the dynamic DE model as the deviations in the expansion history introduced by this model act asymmetrically in redshift space. The DE model fits the SNe data reasonably well, but the available SNe data lacks the statistical power to discriminate between <span>(Lambda CDM)</span> and alternative models. To further assess the model using CMB data, we computed the distance to the last scattering surface and compared the results with that derived from the <i>Planck</i> observations. Although the simple dynamic DE model tested does not completely resolve the tension, it is not ruled out by the data and could still play a role alongside other physical effects.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139661789","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":"Reflecting on accretion in neutron star low-mass X-ray binaries","authors":"Renee M. Ludlam","doi":"10.1007/s10509-024-04281-y","DOIUrl":"10.1007/s10509-024-04281-y","url":null,"abstract":"<div><p>Neutron star low-mass X-ray binaries accrete via Roche-lobe overflow from a stellar companion that is ≲ 1 M_⊙. The accretion disk in these systems can be externally illuminated by X-rays that are reprocessed by the accreting material into an emergent reflection spectrum comprised of emission lines superimposed onto the reprocessed continuum. Due to proximity to the compact object, strong gravity effects are imparted to the reflection spectrum that can be modeled to infer properties of the NS itself and other aspects of the accreting system. This short review discusses the field of reflection modeling in neutron star low-mass X-ray binary systems with the intention to highlight the work that was awarded the 2023 AAS Newton Lacy Pierce Prize, but also to consolidate key information as a reference for those entering this subfield.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139647899","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":"Multibands fitting of Gamma-ray burst’s afterglow’s light curves using the synchrotron external forward shock model","authors":"Yassine Rahmani,&nbsp;Abdelaziz Sid,&nbsp;Mourad Fouka,&nbsp;Saad Ouichaoui,&nbsp;Redouane Mecheri","doi":"10.1007/s10509-024-04279-6","DOIUrl":"10.1007/s10509-024-04279-6","url":null,"abstract":"<div><p>The Swift Gamma-Ray Bursts (GRBs) satellite has observed GRB afterglows with unprecedented resolution over the last two decades, using instruments like the Burst Alert Telescope (BAT), the X-Ray Telescope (XRT), and the Ultra Violet-Optical Telescope (UVOT). This has motivated intensive modeling efforts to interpret these observations, revealing complex light curves with multiple emission mechanisms. Besides two-dimensional hydrodynamical simulations, recent work uses the asymptotic spectral approach to fit observed GRB afterglow light curves and constrain physical parameters. Analytical models, which treat jet dynamics in detail, are rarely used, and their ability to reproduce recent observations is undervalued. This study uses the analytical external shock model to test its ability to perform a joint X-ray and optical/near-Infra-Red (IR) fit to a sample of GRB afterglows light curves chosen based on low/moderate complexity of observed X-ray emissions and availability of their optical/near-IR counterparts. We developed a numerical code that simultaneously solves the fireball model with synchrotron emission for a set of microphysical parameters and performs a Monte-Carlo multi-band fitting analysis based on <span>(chi ^{2})</span> minimization. Results showed reasonable agreement with 70% of the data, with both homogeneous interstellar medium (ISM) and stellar wind (WIND) density models providing relatively equal quality fits, slightly deviating from the data in the latter time evolution phase. Best-fit values of microphysical parameters are consistent with previous results, although they show significant degeneracy leading to mutual correlations. The correlation study confirms the ability of the multi-band fitting to break the degeneracies and increase constraints on physical parameters.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139647889","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":"Constraints on the emergent universe from recent temperature and Hubble data","authors":"Prasenjit Thakur","doi":"10.1007/s10509-024-04277-8","DOIUrl":"10.1007/s10509-024-04277-8","url":null,"abstract":"<div><p>In this paper, the emergent universe model (EU) is explored (as per Mukherjee <span>({mathit{et;al.}})</span>) in a flat scenario with equation of state <span>((EoS))</span> <span>(p=Brho -Arho ^{frac{1}{2}})</span> (where <span>(A)</span> and <span>(B)</span> are constants). Here, the temperature function is evaluated in terms of the EoS parameters and redshift under the conditions of balanced particle creation and annihilation. To examine the thermodynamic evolution and find a viable EU model, constraints on its EoS parameters are determined. First, constraints on <span>(A_{s})</span>, and <span>(B)</span> (where <span>(A_{s} = frac{A}{rho _{eu0}^{frac{1}{2}}})</span> and <span>(rho _{eu0})</span> is the present energy density) are obtained from the acceptable transition redshift limit <span>(z_{tr})</span> and decoupling temperature limit <span>(T_{d})</span> as <span>(A_{s})</span> ≈ <span>((0.84-1.07))</span> and <span>(B)</span> ≈ <span>((0.38-0.42))</span> for the general EU model. Finally, stricter constraints on <span>(z_{tr})</span> are drawn from recent <span>(T(z)-z)</span> and observed Hubble data (OHD). These <span>(z_{tr})</span> and <span>(T_{d})</span> values are then utilized to obtain acceptable limits on <span>(A_{s})</span>, and <span>(B)</span>. On average, the acceptable limits on <span>(z_{tr})</span>, <span>(A_{s})</span>, and <span>(B)</span> are <span>(0.79pm 0.03)</span> (in the 1<span>(sigma )</span> error limit), ≈ <span>((1.11-1.15))</span> and ≈ <span>((0.41-0.43))</span>, respectively, for the general EU model. In the <span>(B=frac{1}{3})</span> model, obtained value <span>(z_{tr}= 0.71pm 0.01)</span> (at the 1<span>(sigma )</span> level). The present values of the EoS parameters are determined, and the viability of the models is examined with plots of the deceleration parameter (<span>(q)</span>), equation of state (<span>(omega )</span>) and squared adiabatic sound speed (<span>(c^{2}_{s})</span>) with redshift (<span>(z)</span>). The distance modulus (<span>(mu )</span>) of this EU model is compared with the HIIG and Union2.1 data. The models with <span>(B)</span> <span>((= -frac{1}{3}, 0))</span>, are not suitable at all according to the present analysis, whereas, the <span>(B=frac{1}{3})</span> model is quite similar to the observations.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139648201","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":"Non-coplanar gravitational lenses and the “communication bridge”","authors":"Viktor T. Toth","doi":"10.1007/s10509-024-04274-x","DOIUrl":"10.1007/s10509-024-04274-x","url":null,"abstract":"<div><p>We investigate the propagation of light signals across multiple gravitational lenses, with particular emphasis on the “communication bridge” scenario of two lenses with collinear source and observer. The lenses are assumed to be non-coplanar, far enough from one another for each lens to be treated independently as thin lenses in the limit of weak gravity. We analyze these scenarios using several different tools, including geometric optics, photon mapping, wave optics and ray tracing. Specifically, we use these tools to assess light amplification and image formation by a two-lens system. We then extend the ray tracing analysis to the case of multiple non-coplanar lenses, demonstrating the complexity of images that are projected even by relatively simple lens configurations. We introduce a simple simulation tool that can be used to analyze lensing by non-coplanar gravitational monopoles in the weak gravity limit, treating them as thin lenses.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139562310","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":"Comparison of unknown gravitational-wave signals in two detectors","authors":"Osvaldo M. Moreschi","doi":"10.1007/s10509-024-04276-9","DOIUrl":"10.1007/s10509-024-04276-9","url":null,"abstract":"<div><p>We present a new measure that can be used to test the hypothesis that a similar signal has been recorded in the strains of two gravitational-wave detectors, without recurring to <i>a priori</i> templates or whitening of the strains.</p><p>For an evaluation of its properties we apply our measure to the LIGO data of the GW150914 event and detect the existence of a similar signal with 99.99% confidence level. We also use the new measure to study the strains in the gravitational-wave observatories for the events 151012_2, GW151012, GW170104 and GW190521; covering in this way a variety of different situations.</p><p>In addition we compare our measure with other standard measures and find that it is stronger for the studied data. Thus we are presenting a new powerful tool for the systematic study of unknown gravitational-wave signals in two or more observatories.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139553453","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}