<div><div>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 <span><math><mo>≥</mo></math></span> 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, <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>X</mi></mrow></msub><mo>></mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>41</mn></mrow></msup><mi>e</mi><mi>r</mi><mi>g</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> while one source, X-5, as an ELX with <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>X</mi></mrow></msub><mo>></mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>40</mn></mrow></msup><mi>e</mi><mi>r</mi><mi>g</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, 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 <span><math><mrow><mi>k</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>∼</mo></mrow></math></span> 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 <span><math><mrow><mi>k</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>∼</mo></mrow></math></span> 0.17 keV and photon index <span><math><mrow><mi>Γ</mi><mo>></mo></mrow></math></span> 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<span><math><mrow><mo>∼</mo><msup><mrow><mi>T</mi></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> 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
{"title":"Studying the nature of Ultraluminous X-ray sources in NGC 1453 with XMM-Newton","authors":"Praveen Kangjam , Dayananda Mayanglambam , A. Senorita Devi , Akram Chandrajit Singha","doi":"10.1016/j.newast.2025.102371","DOIUrl":"10.1016/j.newast.2025.102371","url":null,"abstract":"<div><div>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 <span><math><mo>≥</mo></math></span> 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, <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>X</mi></mrow></msub><mo>></mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>41</mn></mrow></msup><mi>e</mi><mi>r</mi><mi>g</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> while one source, X-5, as an ELX with <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>X</mi></mrow></msub><mo>></mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>40</mn></mrow></msup><mi>e</mi><mi>r</mi><mi>g</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, 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 <span><math><mrow><mi>k</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>∼</mo></mrow></math></span> 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 <span><math><mrow><mi>k</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>∼</mo></mrow></math></span> 0.17 keV and photon index <span><math><mrow><mi>Γ</mi><mo>></mo></mrow></math></span> 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<span><math><mrow><mo>∼</mo><msup><mrow><mi>T</mi></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> 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":"2025-08-01","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}
Pub Date : 2025-08-01Epub Date: 2025-02-28DOI: 10.1016/j.newast.2025.102378
Ishan Swamy, Deobrat Singh
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 , the string tension is , 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 .
{"title":"Impact on orbital period of X-ray binary systems attached to a cosmic string","authors":"Ishan Swamy, 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":"2025-08-01","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}
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 () and the saturated conduction parameter () significantly influence the dynamical behavior of shocks. The shock location moves away from the BH horizon as and 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 and 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 and parameters may significantly influence the evolution of the BH outbursts.
{"title":"Thermal conduction and thermal-driven winds in magnetized viscous accretion disk dynamics","authors":"Biplob Sarkar , Indu Kalpa Dihingia , 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":"2025-08-01","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}
Pub Date : 2025-08-01Epub Date: 2025-02-15DOI: 10.1016/j.newast.2025.102373
Mayukh R. Gangopadhyay , Nilanjana Kumar , Ankan Mukherjee , Mohit K. Sharma
A pseudo-Nambu Goldstone Boson (pNGB) arising from the breaking of a global symmetry () 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 develops a potential through its couplings with the particles that do not form the complete representations of . 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.
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.
{"title":"Composite pseudo Nambu Goldstone quintessence","authors":"Mayukh R. Gangopadhyay , Nilanjana Kumar , Ankan Mukherjee , 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":"2025-08-01","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}
Pub Date : 2025-08-01Epub Date: 2025-02-16DOI: 10.1016/j.newast.2025.102372
Mustafa Turan Sağlam , Can Güngör , Tuğçe Kocabıyık
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& Aql X-1, via Z 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 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 power over time and flagged the time intervals exceeding defined threshold levels for each source as pulse candidates. 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 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 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.
{"title":"An elaborate search for coherent pulsations from Intermittent–AMXPs","authors":"Mustafa Turan Sağlam , Can Güngör , 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& 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":"2025-08-01","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}
Pub Date : 2025-08-01Epub Date: 2025-02-23DOI: 10.1016/j.newast.2025.102375
Vojtěch Šimon
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. Bursts of mass transfer from the donor are likely to contribute to the short high-state episodes.
{"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":"2025-08-01","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}
Pub Date : 2025-08-01Epub Date: 2025-02-22DOI: 10.1016/j.newast.2025.102374
Ilham Nasiroglu
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 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 . 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 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.
本研究通过分析2015年至2021年间三台望远镜新收集的30次月食中期数据，重新审视了短周期食双星系统XY狮子座（W -subtype W Ursae Majoris （wuma）接触双星）的轨道周期变化。获得的光曲线和残差显示没有可归因于脉动或星斑等影响的偏差。更新后的O−C图涵盖了77年的时间，并增加了4年的新数据，显示出与以前发表的模型有轻微的偏差。采用MCMC采样方法，对XY Leo的轨道周期变化进行了三种模型分析。模型1包括线性星历、二次项和绕中心双星系统运行的第三个天体的光行时（LTT）效应。模型II和模型III分别为磁周期和第4个体的LTT效应增加了正弦函数。第三个天体的更新轨道参数比之前的估计略大，除了e3。磁周期的Applegate机制分析表明可能存在磁活动，但推导出的周期（28.09年）超出了预期范围。模型III第一次考虑了第4个体，产生了最低的均方根和系统误差，表明与O−C图有更好的兼容性。轨道稳定性测试证实，模型I和模型II的轨道在1 Myr内是稳定的，而模型III则不稳定。模型I残差中的持续振荡表明，轨道周期的变化需要额外的解释，例如磁周期或其他伴星的影响。
{"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":"2025-08-01","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}
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.
{"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 , Suman Garia , Deepak Pandey , Meena Pokharia , 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":"2025-08-01","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}
Pub Date : 2025-07-01Epub Date: 2025-01-18DOI: 10.1016/j.newast.2025.102355
Bhupendra Kumar Shukla , R.K. Tiwari , A. Beesham , Değer Sofuoğlu
In this study, we investigate Modified Chaplygin gas solutions within the framework of theory of gravity, a modified gravitational theory that seeks to address the limitations of the conventional Lambda cold dark matter model. gravity offers a novel perspective on cosmic dynamics by incorporating a non-minimal coupling between the geometry and the matter, allowing for a richer understanding of the expansion of the universe. We explore the implications of modified Chaplygin gas, characterized by its unique equation of state (eos), which transitions from a matter-dominated phase to a dark energy-dominated phase, thereby influencing the evolution of the energy density and pressure across cosmic redshifts. Our findings reveal significant insights into the interplay between different energy components, highlighting the transition from positive to negative pressure as a hallmark of the role of dark energy in driving the accelerated expansion of the universe. This research not only enhances our comprehension of cosmic evolution, but also provides a compelling framework for future investigations into the nature of dark energy and its impact on the ultimate fate of the universe.
{"title":"Modified Chaplygin gas solutions of f(Q) theory of gravity","authors":"Bhupendra Kumar Shukla , R.K. Tiwari , A. Beesham , Değer Sofuoğlu","doi":"10.1016/j.newast.2025.102355","DOIUrl":"10.1016/j.newast.2025.102355","url":null,"abstract":"<div><div>In this study, we investigate Modified Chaplygin gas solutions within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> theory of gravity, a modified gravitational theory that seeks to address the limitations of the conventional Lambda cold dark matter model. <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity offers a novel perspective on cosmic dynamics by incorporating a non-minimal coupling between the geometry and the matter, allowing for a richer understanding of the expansion of the universe. We explore the implications of modified Chaplygin gas, characterized by its unique equation of state (eos), which transitions from a matter-dominated phase to a dark energy-dominated phase, thereby influencing the evolution of the energy density and pressure across cosmic redshifts. Our findings reveal significant insights into the interplay between different energy components, highlighting the transition from positive to negative pressure as a hallmark of the role of dark energy in driving the accelerated expansion of the universe. This research not only enhances our comprehension of cosmic evolution, but also provides a compelling framework for future investigations into the nature of dark energy and its impact on the ultimate fate of the universe.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"117 ","pages":"Article 102355"},"PeriodicalIF":1.9,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153389","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}
Pub Date : 2025-07-01Epub Date: 2025-01-14DOI: 10.1016/j.newast.2025.102352
Neslihan Alan , Fahri Aliçavuş , Mehmet Alpsoy
The observations of eclipsing binary systems are of great importance in astrophysics, as they allow direct measurements of fundamental stellar parameters. By analysing high-quality space-based observations with ground-based photometric data, it becomes possible to detect these fundamental parameters with greater precision using multicolour photometry. Here, we report the first photometric analysis results of the V517 Cam eclipsing binary system by combining the Transiting Exoplanet Survey Satellite (TESS) light curve and new CCD observations in BVRI filters, obtained with a 60 cm robotic telescope (T60) at the TÜBİTAK National Observatory. By means of photometric analyses, the masses and radii of the primary and secondary stars were carefully determined to be , , and , , respectively. Furthermore, the distance to V517 Cam was calculated to be pc. The overall age of the system is estimated to be around Myr. At this age, the primary component stands near the onset of its main-sequence evolution, near the ZAMS, whereas the secondary component remains in the pre-main-sequence evolutionary phase. To better understand the evolutionary status and nature of V517 Cam, the mass ratio and temperature values, obtained with relatively low sensitivity by photometric measurements, need to be confirmed by spectral analysis.
{"title":"First photometric investigation of V517 Cam combined with ground-based and TESS data","authors":"Neslihan Alan , Fahri Aliçavuş , Mehmet Alpsoy","doi":"10.1016/j.newast.2025.102352","DOIUrl":"10.1016/j.newast.2025.102352","url":null,"abstract":"<div><div>The observations of eclipsing binary systems are of great importance in astrophysics, as they allow direct measurements of fundamental stellar parameters. By analysing high-quality space-based observations with ground-based photometric data, it becomes possible to detect these fundamental parameters with greater precision using multicolour photometry. Here, we report the first photometric analysis results of the V517 Cam eclipsing binary system by combining the Transiting Exoplanet Survey Satellite (<em>TESS</em>) light curve and new CCD observations in <em>BVRI</em> filters, obtained with a 60 cm robotic telescope (T60) at the TÜBİTAK National Observatory. By means of photometric analyses, the masses and radii of the primary and secondary stars were carefully determined to be <span><math><mrow><msub><mrow><mi>M</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mn>1</mn><mo>.</mo><mn>47</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>06</mn><mspace></mspace><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span>, <span><math><mrow><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>79</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>05</mn><mspace></mspace><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span>, and <span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mn>1</mn><mo>.</mo><mn>43</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>03</mn><mspace></mspace><msub><mrow><mi>R</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span>, <span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>75</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>04</mn><mspace></mspace><msub><mrow><mi>R</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span>, respectively. Furthermore, the distance to V517 Cam was calculated to be <span><math><mrow><mn>284</mn><mo>±</mo><mn>20</mn></mrow></math></span> pc. The overall age of the system is estimated to be around <span><math><mrow><mn>63</mn><mo>±</mo><mn>15</mn></mrow></math></span> Myr. At this age, the primary component stands near the onset of its main-sequence evolution, near the ZAMS, whereas the secondary component remains in the pre-main-sequence evolutionary phase. To better understand the evolutionary status and nature of V517 Cam, the mass ratio and temperature values, obtained with relatively low sensitivity by photometric measurements, need to be confirmed by spectral analysis.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"117 ","pages":"Article 102352"},"PeriodicalIF":1.9,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152960","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}
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