New Astronomy最新文献

{"title":"Impact on orbital period of X-ray binary systems attached to a cosmic string","authors":"Ishan Swamy,&nbsp;Deobrat Singh","doi":"10.1016/j.newast.2025.102378","DOIUrl":"10.1016/j.newast.2025.102378","url":null,"abstract":"<div><div>Cosmic strings attached to rotating black holes extract its rotational energy, resulting in a mass loss and reduced spin. In this paper we discuss the proposed methods to detect these phenomena and present a novel methodology based on existing literature, by considering a Low Mass X-ray binary system. We investigate the impact of a cosmic string interacting with a black hole in an X-ray binary system and attempt to explain the observations of unexpected orbital period changes in such systems by proposing mass loss by cosmic strings to be a potential cause. For a period change of order <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math></span>, the string tension is <span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>17</mn></mrow></msup></mrow></math></span>, lying in the predicted range for cosmic string tension. An analysis of multiple low mass X-ray binary systems is carried out and it is shown that a significant and observable change occurs for a string tension <span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>11</mn></mrow></msup></mrow></math></span>.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102378"},"PeriodicalIF":1.9,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526989","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":"Thermal conduction and thermal-driven winds in magnetized viscous accretion disk dynamics","authors":"Biplob Sarkar ,&nbsp;Indu Kalpa Dihingia ,&nbsp;Ranjeev Misra","doi":"10.1016/j.newast.2025.102377","DOIUrl":"10.1016/j.newast.2025.102377","url":null,"abstract":"<div><div>This paper investigates the effects of saturated thermal conduction (TC) and thermal-driven winds (TDWs) on magnetized advection-dominated accretion onto a rotating black hole (BH). We incorporate dissipative processes in the magnetized accretion flow and expect the accretion disk to be threaded by predominantly toroidal and turbulent magnetic fields. We solve the magnetohydrodynamics equations and construct a self-consistent steady model of the magnetized accretion flow surrounding a rotating BH, which includes TC and TDWs. We seek global accretion solutions spanning from the BH horizon to a large distance and analyze the solution’s characteristics as a function of dissipation parameters. Accretion solutions with multiple critical points may exhibit shock waves if they meet the standing shock criteria. We found steady, global transonic, and shocked accretion solutions around the rotating BH. In particular, the wind parameter (<span><math><mi>m</mi></math></span>) and the saturated conduction parameter (<span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>) significantly influence the dynamical behavior of shocks. The shock location moves away from the BH horizon as <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <span><math><mi>m</mi></math></span> increase, assuming fixed conditions at the disk’s outer edge. Our formalism explains the declining phase of BH outbursts, characterized by a monotonic decrease in QPO frequency as the burst decays. Based on our findings, we conclude that the combined effect of <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <span><math><mi>m</mi></math></span> parameters substantially alters the steady shock specific energy vs angular momentum parameter space and also modifies the corresponding post-shock luminosity vs QPO frequency parameter space. We propose, based on our theoretical model, that the <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <span><math><mi>m</mi></math></span> parameters may significantly influence the evolution of the BH outbursts.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102377"},"PeriodicalIF":1.9,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143549349","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 discrepant long-term activities of the polars BY Camelopardalis and AR Ursae Majoris","authors":"Vojtěch Šimon","doi":"10.1016/j.newast.2025.102375","DOIUrl":"10.1016/j.newast.2025.102375","url":null,"abstract":"<div><div>Polars are cataclysmic variables with strongly magnetized white dwarfs (WDs). This analysis of the long-term optical activity of two polars (BY<!--> <!-->Cam and AR<!--> <!-->UMa) used the light curves of CCD data from the ZTF and CRTS and photographic data from the DASCH databases. These two polars display remarkably discrepant long-term activities. The high-state activity dominated BY<!--> <!-->Cam, except for a short and shallow low-state episode. A fit to BY<!--> <!-->Cam’s light curve shows long-term brightness changes in the high state. We ascribe the variable profiles of the histograms of the residuals of this fit (1-year bins) to the changes in the dominance of the individual accretion modes and accreting regions on the WD with time (hundreds of days). The high-state episodes (no matter how long and bright) of AR<!--> <!-->UMa occurred from a relatively stable low-state brightness level. The superorbital changes of AR<!--> <!-->UMa dominated in the high states. <strong>Bursts of mass transfer from the donor are likely to contribute to the short high-state episodes.</strong></div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102375"},"PeriodicalIF":1.9,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487068","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":"Investigation of the correlation between geomagnetic storms and cosmic ray intensity as well as cosmic ray intensity variation with solar wind parameters during three consecutive solar cycles 23, 24, and 25","authors":"Nisha Kohli ,&nbsp;Suman Garia ,&nbsp;Deepak Pandey ,&nbsp;Meena Pokharia ,&nbsp;Megha Agari","doi":"10.1016/j.newast.2025.102387","DOIUrl":"10.1016/j.newast.2025.102387","url":null,"abstract":"<div><div>A systematic correlation study has been performed in order to establish a significant association between CRI (cosmic ray intensity) and the following parameters: flow pressure, solar wind speed, plasma proton density, solar wind plasma temperature, and IMF (interplanetary magnetic field) for solar cycles 23 and 24, as well as the most recent solar cycle 25. To do this, we used a Chree analysis by superposed-epoch technique to investigate the link between hour-to-hour changes of CRI and the above-mentioned parameters. We found that there is a strong link between CRI and solar wind speed when compared to IMF. This suggests that solar wind speed is a more capable parameter than IMF to cause a decline in CRI. It was observed that for all three solar cycles, there is an inverse correlation between IMF and solar wind speed and a positive correlation between Dst and CRI. We found that solar wind plasma temperature, flow pressure, and plasma proton density have weak correlations with CRI, making them ineffective for CRs (cosmic rays). For all three solar cycles' intense and severe storms, we have discovered a very interesting and adequate result: maximum decline in CRI is observed on the days of minimal Dst (0–11hrs), IMF maximum (0–19hrs), and peak solar wind speed (0–15hrs). We discovered that the instantaneous modulation of CRI is caused by both the solar wind speed and the IMF. Notable behavior was displayed in the years 1999, 2000, 2004, 2014, 2016 2018, and 2023.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102387"},"PeriodicalIF":1.9,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519685","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":"Studying orbital period variations of XY Leo through updated eclipse times and multi-model analysis","authors":"Ilham Nasiroglu","doi":"10.1016/j.newast.2025.102374","DOIUrl":"10.1016/j.newast.2025.102374","url":null,"abstract":"<div><div>This study revisits the orbital period variation of the short-period eclipsing binary system XY Leo, a W-subtype W Ursae Majoris (W UMa) contact binary, by analyzing 30 newly collected mid-eclipse times from three telescopes between 2015 and 2021. The obtained light curves and residuals showed no deviations attributable to effects like pulsations or starspots. The updated <span><math><mrow><mi>O</mi><mo>−</mo><mi>C</mi></mrow></math></span> diagram, covering 77 years and extended by four years of new data, revealed minor deviations from previously published models. Three models were applied using MCMC sampling to analyze the orbital period variations of XY Leo. Model I includes the linear ephemeris, a quadratic term, and the Light Travel Time (LTT) effect of a 3rd body orbiting the central binary system. Models II and III add a sinusoidal function for the magnetic cycle and the LTT effect of a 4th body to Model I, respectively. Updated orbital parameters for the 3rd body are slightly larger than earlier estimates, except for <span><math><msub><mrow><mi>e</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>. Applegate mechanism analysis of the magnetic cycle indicated possible magnetic activity, though the derived period (28.09 years) exceeds the expected range. For the first time, Model III considers a 4th body, yielding the lowest RMS and systematic error, suggesting better compatibility with the <span><math><mrow><mi>O</mi><mo>−</mo><mi>C</mi></mrow></math></span> diagram. Orbital stability tests confirmed stable orbits for Models I and II over one Myr, while Model III showed no stability. Persistent oscillations in Model I residuals suggest that the orbital period variation requires additional explanations, such as magnetic cycles or the influence of further companions.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102374"},"PeriodicalIF":1.9,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512601","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":"An elaborate search for coherent pulsations from Intermittent–AMXPs","authors":"Mustafa Turan Sağlam ,&nbsp;Can Güngör ,&nbsp;Tuğçe Kocabıyık","doi":"10.1016/j.newast.2025.102372","DOIUrl":"10.1016/j.newast.2025.102372","url":null,"abstract":"<div><div>We present a detailed systematic pulse search for three Intermittent-Accreting Millisecond X-ray Pulsars (Intermittent-AMXPs), HETE J1900.1-2455, SAX J1748.9-2021&amp; Aql X-1, via Z<span><math><msubsup><mrow></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> and maximum likelihood (ML) techniques by using 16 years data of Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) in the energy range of 3.0–13.0 keV. We first performed a pulse scan using the Z<span><math><msubsup><mrow></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> technique in millisecond sensitivities for every 25 s time interval with 1 s shifts to cover all data set around the detected frequencies given in the literature. We tracked the Z<span><math><msubsup><mrow></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> power over time and flagged the time intervals exceeding defined threshold levels for each source as <em>pulse candidates</em>. The detected pulse list throughout our scan has new discoveries while covering the pulsed regions presented in the literature. For a deeper search, using the pulses obtained from the Z<span><math><msubsup><mrow></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> method as a probability density function as an input parameter, we re-scanned the time intervals centered on the detected pulse via ML. The detected pulse-on duration via ML is slightly longer than the one via Z<span><math><msubsup><mrow></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> method. This phenomenon allows us to argue for the existence of the smooth transition between pulse-on and pulse-off stages. For SAX J1748.9-2021, we also obtained orbital period by using the systematic pulse arrival phase patterns throughput of ML to be 8.76 h.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102372"},"PeriodicalIF":1.9,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453030","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":"Composite pseudo Nambu Goldstone quintessence","authors":"Mayukh R. Gangopadhyay ,&nbsp;Nilanjana Kumar ,&nbsp;Ankan Mukherjee ,&nbsp;Mohit K. Sharma","doi":"10.1016/j.newast.2025.102373","DOIUrl":"10.1016/j.newast.2025.102373","url":null,"abstract":"<div><div>A pseudo-Nambu Goldstone Boson (pNGB) arising from the breaking of a global symmetry (<span><math><mrow><mi>G</mi><mo>→</mo><mi>H</mi></mrow></math></span>) can be one of the most promising candidate for the quintessence model, to explain the late time acceleration of our universe. Motivated from the Composite Higgs scenario, we have investigated the case where the pNGB associated with <span><math><mrow><mi>S</mi><mi>O</mi><mrow><mo>(</mo><mi>N</mi><mo>)</mo></mrow><mo>/</mo><mi>S</mi><mi>O</mi><mrow><mo>(</mo><mi>N</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span> develops a potential through its couplings with the particles that do not form the complete representations of <span><math><mi>G</mi></math></span>. The Coleman Weinberg (CW) potential is generated via the external particles in the loop which are linked with the strongly interacting dynamics and can be computed predicatively.</div><div>The model of Dark Energy (DE) is tested against several latest cosmological observations such as supernovae data of Pantheon, Baryon Acoustic Oscillation (BAO), Redshift-space distortion (RSD) data etc. We have found that the fit prefers sub-Planckian value of the pNGB field decay constant. Moreover, we have found that the model predicts cosmological parameters well within the allowed range of the observation and thus gives a well motivated model of quintessence.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102373"},"PeriodicalIF":1.9,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436863","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":"Studying the nature of Ultraluminous X-ray sources in NGC 1453 with XMM-Newton","authors":"Praveen Kangjam ,&nbsp;Dayananda Mayanglambam ,&nbsp;A. Senorita Devi ,&nbsp;Akram Chandrajit Singha","doi":"10.1016/j.newast.2025.102371","DOIUrl":"10.1016/j.newast.2025.102371","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This paper presents a multi epoch, detailed spectral and temporal analysis of the non-nuclear X-ray point sources of the massive elliptical galaxy NGC 1453, based on two XMM-Newton observational data. In the observation with Obs ID 0901620101, seven sources having net counts &lt;span&gt;&lt;math&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; 100 were identified for PN data, which along with their corresponding MOS data were considered for the analysis. For the observation with Obs ID 0673770601, only three sources were found for PN and two sources for MOS-1 and MOS-2. The spectra of all the sources were simultaneously fitted using two empirical models: an absorbed power-law model and an absorbed disk blackbody model. Based on the estimated bolometric luminosities of the sources, six sources - X-1, X-2, X-3, X-4, X-6 and X-7 are categorized as HLXs with X-ray luminosity, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;41&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; while one source, X-5, as an ELX with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;40&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, within the error limit. Notably, for source X-1, the disk blackbody component is the dominant feature in both the observations. In the 2012 observation (Obs ID 0673770601), the source exhibits a soft, cool accretion disk with an inner disk temperature of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; 0.27 keV. By 2022 (Obs ID 0901620101), X-1 presents an even softer, supersoft spectrum, characterized by a significantly lower inner disk temperature of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; 0.17 keV and photon index &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; 5. This shift over the span of a decade indicates a further softening of the source. In the present study, due to limited data availability, the Luminosity-Temperature (L-T) relation could not be strictly constrained. However, for the purpose of mass estimation, we have assumed that the L&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; relation holds. The observed further softening of the source (X-1), accompanied by a slight increase in luminosity in the later observation, suggests a potential inverse correlation between the inner disk temperature of the soft component and luminosity, which is consistent with the characteristics of beamed disk emission resulting from radiatively","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"118 ","pages":"Article 102371"},"PeriodicalIF":1.9,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422000","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":"MeerKAT-based multi-wavelength study of supernova remnant G7.7-3.7 (SN386?)","authors":"Patrick N. Mwaniki ,&nbsp;James O. Chibueze ,&nbsp;Dismas S. Wamalwa","doi":"10.1016/j.newast.2025.102370","DOIUrl":"10.1016/j.newast.2025.102370","url":null,"abstract":"<div><div>We investigated the structural characteristics of G7.7-3.7 at a higher resolution of 1284 MHz. MeerKAT observations revealed that G7.7-3.7 had an asymmetric spherical structure with filamentary features and various blowouts. The western boundary showed a strong bright blowout, while the southern perimeter showcased extended bright filaments with feather-like structures, which seemed disconnected from the western blowout. Moreover, the eastern region exhibited a blowout centered around a bright point source, with faint, elongated filaments extending north-west. These filaments connected the eastern point source to the western blowout, creating a uniform outward progression. Spectral index analysis indicated a steep spectrum (<span><math><mi>α</mi></math></span> ranged <span><math><mo>∼</mo></math></span> 0 to <span><math><mo>∼</mo></math></span> −3), suggesting a combination of synchrotron and a few traces of thermal emissions concentrated at the edges of bright blowouts. Analysis of MeerKAT and VLA data revealed that G7.7-3.7 had expanded by 9 ± 0.45 arcsec over a period of 31.907 years, corresponding to an expansion rate of 0.282 ± 0.014 arcsec yr⁻¹. This expansion indicated a shock speed of 5883 ± 294 km s⁻¹ and an age of 1636 ± 115 years. This age fits with the supernova explosion event of 386 CE and the MeerKAT observed data in 2023. The multi-wavelength investigation unveiled a distinctive structure within the southern radio blowout, encompassing a bright radio blowout, a prominent X-ray arc, and two faint optical filaments aligned with the X-ray bright arc. We attributed the bright radio blowouts to inhomogeneous mass outflow from shock-accelerated particles and the weakening of magnetic fields along its perimeter. Traces of thermal emissions, especially along the edges of blowouts, were likely due to shock-heated gas, which intensified in the southern region amid high-density Interstellar Medium (ISM). Therefore, these results supported a scenario in which the progenitor supernova of G7.7-3.7 exploded within ISM of varying density, generating the observed X-ray emissions and faint optical filaments. Our findings provided valuable insights into the dynamics and evolution of supernova remnants.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"117 ","pages":"Article 102370"},"PeriodicalIF":1.9,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387699","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":"Prospects for high-resolution probes of galaxy dynamics tracing background cosmology in MaNGA","authors":"Gyeong-Min Lee ,&nbsp;Maurice H.P.M. van Putten","doi":"10.1016/j.newast.2025.102360","DOIUrl":"10.1016/j.newast.2025.102360","url":null,"abstract":"<div><div>Large-<span><math><mi>N</mi></math></span> galaxy surveys offer unprecedented opportunities to probe weak gravitation in galaxy dynamics that may contain correlations tracing background cosmology. Of particular interest is the potential of finite sensitivities to the background de Sitter scale of acceleration <span><math><mrow><msub><mrow><mi>a</mi></mrow><mrow><mi>d</mi><mi>S</mi></mrow></msub><mo>=</mo><mi>c</mi><mi>H</mi></mrow></math></span>, where <span><math><mi>H</mi></math></span> is the Hubble parameter and <span><math><mi>c</mi></math></span> is the velocity of light. At sufficiently large <span><math><mi>N</mi></math></span>, this is possibly probed by ensemble-averaged (“stacked”) rotation curves (RCs) at resolutions on par with present estimates of the Hubble parameter <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>. Here, we consider the prospect for these studies using the large <span><math><mi>N</mi></math></span> <em>Mapping Nearby Galaxies at Apache Point Observatory</em> MaNGA at APO survey. In a first and preliminary step, we consider unbiased control of sub-sample size by consistency in the three Position Angles, <span><math><mi>θ</mi></math></span> , from photometry and velocity fields of gas and stars by spectroscopy within 30°. In sub-samples of size <span><math><mrow><mi>N</mi><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>i</mi></mrow></msub><mrow><mo>(</mo><mi>θ</mi><mo>)</mo></mrow></mrow></math></span>, the scatter in-the-mean <span><math><mrow><mi>σ</mi><mo>/</mo><msqrt><mrow><mi>N</mi></mrow></msqrt></mrow></math></span> is found to reach one percent levels, differentiated over inclination angle <span><math><mi>i</mi></math></span> and <span><math><mi>θ</mi></math></span>. In regular propagation of uncertainties, this scatter contributes <span><math><mrow><mi>κ</mi><mi>σ</mi><mo>/</mo><msqrt><mrow><mi>N</mi></mrow></msqrt></mrow></math></span> to the standard error in-the-mean to the observable, where <span><math><mi>κ</mi></math></span> is determined by the choice of observables. As a lower bound to scatter in stacked RCs, MaNGA hereby appears promising for high-resolution analysis of sensitivity to RCs to background cosmology, notably across a sharp <span><math><msup><mrow><mi>C</mi></mrow><mrow><mn>0</mn></mrow></msup></math></span>-transition (van Putten, 2018) of Newtonian to anomalous dynamics across <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>d</mi><mi>S</mi></mrow></msub></math></span> and, further out, the baryonic Tully–Fisher relation. In turn, these markers provide a novel measurement of cosmological parameters including <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"117 ","pages":"Article 102360"},"PeriodicalIF":1.9,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153393","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}