Pub Date : 2026-03-01Epub Date: 2026-01-12DOI: 10.1016/j.jheap.2026.100556
Manish Yadav , Archana Dixit , M.S. Barak , Anirudh Pradhan
In this study, we investigate the oscillatory dark energy model wsinCDM based on the DESI BAO data together with OHD, Pantheon Plus, and SH0ES measurements. We examine how the DESI data influence the dark energy equation-of-state plane (w0, wa) within cosmological models that are free from Hubble tension and employ a Monte Carlo Markov Chain (MCMC) approach. Our findings indicate that although the parameter space still favors wa < 0 and , the cosmological constant remains consistent with the DESI+OHD+PP combination at the 2σ level. We also observe that the best-fit Hubble constant H0 is higher for the DESI+OHD+PP+SH0ES data combination, leading to a residual Hubble tension of less than 1σ to remain consistent with the SH0ES measurement. These results suggest that attempts to address the Hubble tension tend to reduce indication of DESI for the oscillatory dark energy model. Therefore, claims that the cosmological constant should be approached with greater caution, considering both the latest observational datasets and the existing cosmological tensions. We also obtained the present deceleration parameter and the effective equation-of-state value as and , respectively, for the DESI+OHD+PP+SH0ES dataset combination. Further analysis indicated a strong departure of w0 from at the 4σ level for the DR2+OHD+DES-5yr data combination. The inferred Ωm tended to shift toward higher values when supernova samples were included, indicating a systematic preference for larger Ωm in combinations involving supernova data.
{"title":"Dynamical oscillations in dark energy: Joint constraints on the wsinCDM model from DESI, OHD, and supernova samples","authors":"Manish Yadav , Archana Dixit , M.S. Barak , Anirudh Pradhan","doi":"10.1016/j.jheap.2026.100556","DOIUrl":"10.1016/j.jheap.2026.100556","url":null,"abstract":"<div><div>In this study, we investigate the oscillatory dark energy model <em>w</em><sub>sin</sub>CDM based on the DESI BAO data together with OHD, Pantheon Plus, and SH0ES measurements. We examine how the DESI data influence the dark energy equation-of-state plane (<em>w</em><sub>0</sub>, <em>w<sub>a</sub></em>) within cosmological models that are free from Hubble tension and employ a Monte Carlo Markov Chain (MCMC) approach. Our findings indicate that although the parameter space still favors <em>w<sub>a</sub></em> < 0 and <span><math><mrow><msub><mi>w</mi><mn>0</mn></msub><mo>></mo><mo>−</mo><mn>1</mn></mrow></math></span>, the cosmological constant remains consistent with the DESI+OHD+PP combination at the 2<em>σ</em> level. We also observe that the best-fit Hubble constant <em>H</em><sub>0</sub> is higher for the DESI+OHD+PP+SH0ES data combination, leading to a residual Hubble tension of less than 1<em>σ</em> to remain consistent with the SH0ES measurement. These results suggest that attempts to address the Hubble tension tend to reduce indication of DESI for the oscillatory dark energy model. Therefore, claims that the cosmological constant should be approached with greater caution, considering both the latest observational datasets and the existing cosmological tensions. We also obtained the present deceleration parameter and the effective equation-of-state value as <span><math><mrow><msub><mi>q</mi><mn>0</mn></msub><mo>=</mo><mo>−</mo><mn>0.36</mn></mrow></math></span> and <span><math><mrow><msub><mi>w</mi><mtext>eff</mtext></msub><mo>=</mo><mo>−</mo><mn>0.57</mn></mrow></math></span>, respectively, for the DESI+OHD+PP+SH0ES dataset combination. Further analysis indicated a strong departure of <em>w</em><sub>0</sub> from <span><math><mrow><mi>w</mi><mo>=</mo><mo>−</mo><mn>1</mn></mrow></math></span> at the 4<em>σ</em> level for the DR2+OHD+DES-5yr data combination. The inferred Ω<sub><em>m</em></sub> tended to shift toward higher values when supernova samples were included, indicating a systematic preference for larger Ω<sub><em>m</em></sub> in combinations involving supernova data.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100556"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037530","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 : 2026-03-01Epub Date: 2026-01-12DOI: 10.1016/j.jheap.2026.100554
Jessica Santiago , Kerkyra Asvesta , Maria Giovanna Dainotti , Pisin Chen
We present a new analysis of cosmic dipole anisotropy using gamma-ray bursts (GRBs) as high-redshift standardizable candles. GRBs are ideal probes for testing the cosmological principle thanks to their high luminosity, wide redshift range, and nearly isotropic sky coverage. For the first time, we employ the luminosity—time (L-T) relation, known in the literature as the bidimensional X-ray Dainotti relation, corrected for redshift evolution, to standardize a sample of 176 long GRBs detected by Swift. We test for dipolar modulations in the GRB Hubble diagram using both the Dipole Fit Method and a new approach introduced here, the Anisotropic Residual Analysis Method. Both methods yield consistent results: a dipole amplitude of Ad ≃ 0.6 ± 0.2 pointing towards (RA, DEC) (equatorial coordinates). As shown in the Appendix, this corresponds to a boost velocity of the observer with respect to the GRB rest-frame in the antipodal direction from the dipole direction. Extensive isotropy tests and 20,000 Monte Carlo simulations confirm that the detected signal cannot be explained by chance alignments or by the angular distribution of the GRB sample. We also show how, by incorporating a dipole term, residual correlations are eliminated, showing that the dipole model provides a better fit than standard isotropic ΛCDM.
{"title":"Measuring cosmic dipole with the GRB luminosity-time relation","authors":"Jessica Santiago , Kerkyra Asvesta , Maria Giovanna Dainotti , Pisin Chen","doi":"10.1016/j.jheap.2026.100554","DOIUrl":"10.1016/j.jheap.2026.100554","url":null,"abstract":"<div><div>We present a new analysis of cosmic dipole anisotropy using gamma-ray bursts (GRBs) as high-redshift standardizable candles. GRBs are ideal probes for testing the cosmological principle thanks to their high luminosity, wide redshift range, and nearly isotropic sky coverage. For the first time, we employ the luminosity—time (L-T) relation, known in the literature as the bidimensional X-ray Dainotti relation, corrected for redshift evolution, to standardize a sample of 176 long GRBs detected by <em>Swift</em>. We test for dipolar modulations in the GRB Hubble diagram using both the Dipole Fit Method and a new approach introduced here, the Anisotropic Residual Analysis Method. Both methods yield consistent results: a dipole amplitude of <em>A<sub>d</sub></em> ≃ 0.6 ± 0.2 pointing towards (RA, DEC) <span><math><mrow><mo>≈</mo><mo>(</mo><msup><mn>134</mn><mo>∘</mo></msup><mo>±</mo><msup><mn>30</mn><mo>∘</mo></msup><mo>,</mo><mo>−</mo><msup><mn>36</mn><mo>∘</mo></msup><mo>±</mo><msup><mn>21</mn><mo>∘</mo></msup><mo>)</mo></mrow></math></span> (equatorial coordinates). As shown in the Appendix, this corresponds to a boost velocity of the observer with respect to the GRB rest-frame in the antipodal direction from the dipole direction. Extensive isotropy tests and 20,000 Monte Carlo simulations confirm that the detected signal cannot be explained by chance alignments or by the angular distribution of the GRB sample. We also show how, by incorporating a dipole term, residual correlations are eliminated, showing that the dipole model provides a better fit than standard isotropic ΛCDM.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100554"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076894","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 : 2026-03-01Epub Date: 2026-01-20DOI: 10.1016/j.jheap.2026.100559
Ruo-Yu Guan , Fei-Fei Wang , Yuan-Chuan Zou
Gamma-ray bursts (GRBs) rank among the most powerful astrophysical phenomena, characterized by complex and highly variable prompt emission light curves that reflect the dynamics of their central engines. In this work, we analyze a sample of 163 long-duration GRBs detected by the Burst and Transient Source Experiment (BATSE), applying detrended fluctuation analysis (DFA) to derive the Hurst index as a quantitative descriptor of temporal correlations in the light curves. We further explore statistical correlations between the Hurst index and 12 other observational parameters through regression and correlation analyses. Our results reveal anti-correlations between the Hurst index and the burst durations (T50, T90), and moderate positive correlations with peak photon flux proxies (Ppk1–Ppk3). By contrast, the standard spectral parameters (including the low-energy index α) show no evidence for a linear dependence on the Hurst index in our sample. We do not find a clear monotonic weakening of the correlation strength from 64 ms to 1024 ms peak-flux measures; rather, the correlation coefficients for Ppk1–Ppk3 are comparable within uncertainties. The results offer new perspectives on the temporal structure of the GRB emission and its potential link to the underlying physical mechanisms driving these bursts.
{"title":"Hurst index of gamma-ray burst light curves and its statistical study","authors":"Ruo-Yu Guan , Fei-Fei Wang , Yuan-Chuan Zou","doi":"10.1016/j.jheap.2026.100559","DOIUrl":"10.1016/j.jheap.2026.100559","url":null,"abstract":"<div><div>Gamma-ray bursts (GRBs) rank among the most powerful astrophysical phenomena, characterized by complex and highly variable prompt emission light curves that reflect the dynamics of their central engines. In this work, we analyze a sample of 163 long-duration GRBs detected by the Burst and Transient Source Experiment (BATSE), applying detrended fluctuation analysis (DFA) to derive the Hurst index as a quantitative descriptor of temporal correlations in the light curves. We further explore statistical correlations between the Hurst index and 12 other observational parameters through regression and correlation analyses. Our results reveal anti-correlations between the Hurst index and the burst durations (<em>T</em><sub>50</sub>, <em>T</em><sub>90</sub>), and moderate positive correlations with peak photon flux proxies (P<sub><em>pk</em>1</sub>–P<sub><em>pk</em>3</sub>). By contrast, the standard spectral parameters (including the low-energy index <em>α</em>) show no evidence for a linear dependence on the Hurst index in our sample. We do not find a clear monotonic weakening of the correlation strength from 64 ms to 1024 ms peak-flux measures; rather, the correlation coefficients for P<sub><em>pk</em>1</sub>–P<sub><em>pk</em>3</sub> are comparable within uncertainties. The results offer new perspectives on the temporal structure of the GRB emission and its potential link to the underlying physical mechanisms driving these bursts.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100559"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076895","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}
The AT2017gfo kilonova transient remains a unique multi-messenger event thanks to its proximity () and the possibility to investigate time-resolved spectra, thus providing evidence of r-process nucleosynthesis. The kilonova signal was extensively studied in the spectral and time domains, providing key insights into the chemical composition and physical properties of the ejecta. Here, we report the discovery of a novel correlation between two fundamental observables: the peak energy of the EFE spectrum, Ep, and the isotropic-equivalent luminosity, Liso. In particular, we show that up to about 2.5 days after the merger, the AT2017gfo spectrum evolves according to: while in the subsequent epochs, Ep remains almost constant with Liso, flattening around 1 eV. Exploiting simulations from a state-of-the-art radiative transfer code, we demonstrate that our kilonova model inherently predicts this peculiar correlation, hence suggesting a new diagnostic tool for comparing observables against simulations. Future kilonova observations will provide additional insight into the physics behind the correlation.
{"title":"The Ep−Liso correlation: A new diagnostic tool for kilonova transients","authors":"Ruben Farinelli , Fabrizio Cogato , Mattia Bulla , Paramvir Singh , Giulia Stratta , Andrea Rossi , Eliana Palazzi , Cristiano Guidorzi , Elisabetta Maiorano , Lorenzo Amati , Bing Zhang , Luciano Rezzolla , Filippo Frontera","doi":"10.1016/j.jheap.2025.100532","DOIUrl":"10.1016/j.jheap.2025.100532","url":null,"abstract":"<div><div>The AT2017gfo kilonova transient remains a unique multi-messenger event thanks to its proximity (<span><math><mrow><mi>z</mi><mo>=</mo><mn>0.00987</mn></mrow></math></span>) and the possibility to investigate time-resolved spectra, thus providing evidence of r-process nucleosynthesis. The kilonova signal was extensively studied in the spectral and time domains, providing key insights into the chemical composition and physical properties of the ejecta. Here, we report the discovery of a novel correlation between two fundamental observables: the peak energy of the <em>E</em> <em>F<sub>E</sub></em> spectrum, <em>E</em><sub>p</sub>, and the isotropic-equivalent luminosity, <em>L</em><sub>iso</sub>. In particular, we show that up to about 2.5 days after the merger, the AT2017gfo spectrum evolves according to: <span><math><mrow><msub><mtext>log</mtext><mn>10</mn></msub><mrow><mo>[</mo><msub><mi>E</mi><mrow><mi>p</mi></mrow></msub><mo>/</mo><mtext>eV</mtext><mo>]</mo></mrow><mo>=</mo><mo>−</mo><mn>0</mn><mo>.</mo><msubsup><mn>13</mn><mrow><mo>−</mo><mn>0.02</mn></mrow><mrow><mo>+</mo><mn>0.02</mn></mrow></msubsup><mo>+</mo><mn>0</mn><mo>.</mo><msubsup><mn>62</mn><mrow><mo>−</mo><mn>0.02</mn></mrow><mrow><mo>+</mo><mn>0.02</mn></mrow></msubsup><mspace></mspace><msub><mtext>log</mtext><mn>10</mn></msub><mrow><mo>[</mo><msub><mi>L</mi><mrow><mrow><mi>i</mi></mrow><mi>s</mi><mi>o</mi></mrow></msub><mo>/</mo><mrow><mo>(</mo><msup><mn>10</mn><mn>41</mn></msup><mspace></mspace><mtext>erg</mtext><mspace></mspace><msup><mtext>s</mtext><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>)</mo></mrow><mo>]</mo></mrow><mspace></mspace><mrow><mo>(</mo><mn>68</mn><mspace></mspace><mo>%</mo><mspace></mspace><mrow><mrow><mi>C</mi></mrow><mo>.</mo><mi>L</mi><mo>.</mo></mrow><mo>)</mo></mrow></mrow></math></span> while in the subsequent epochs, <em>E</em><sub>p</sub> remains almost constant with <em>L</em><sub>iso</sub>, flattening around 1 eV. Exploiting simulations from a state-of-the-art radiative transfer code, we demonstrate that our kilonova model inherently predicts this peculiar correlation, hence suggesting a new diagnostic tool for comparing observables against simulations. Future kilonova observations will provide additional insight into the physics behind the <span><math><mrow><msub><mi>E</mi><mrow><mi>p</mi></mrow></msub><mo>−</mo><msub><mi>L</mi><mrow><mrow><mi>i</mi></mrow><mi>s</mi><mi>o</mi></mrow></msub></mrow></math></span> correlation.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100532"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884294","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 : 2026-03-01Epub Date: 2026-01-02DOI: 10.1016/j.jheap.2025.100547
Shaswata Chowdhury , M.A. Krishnakumar , Manjari Bagchi , Bhal Chandra Joshi , Nobleson K , Jibin Jose , Shantanu Desai , Manpreet Singh , Vaishnavi Vyasraj , Kuldeep Meena , Amarnath , Manoneeta Chakraborty , Shubham Kala , Debabrata Deb , Zenia Zuraiq , Arul Pandian B , Neelam Dhanda Batra , Churchil Dwivedi , Sushovan Mondal , Avinash Kumar Paladi , Kunjal Vara
The Indian Pulsar Timing Array (InPTA) has recently published its second data release (DR2), comprising the timing analysis of seven years of data on 27 millisecond pulsars (MSPs), observed simultaneously in the 300 - 500 MHz (band 3) and 1260 - 1460 MHz (band 5), using the upgraded Giant Metrewave Radio Telescope (uGMRT). The low-frequency data, particularly in band 3, is highly sensitive to propagation effects such as dispersion measure (DM) fluctuations, which can be imprints of some astrophysical phenomena (scientific outliers). Here, we analyze the two outliers of possible astrophysical origin coming from the band 3 DM time series of two pulsars: PSR J1022+1001, with an ecliptic latitude of , and PSR J2145 - 0750, one of the brightest MSPs, with multi-component profile morphology. Our study reveals compelling evidence for a coronal mass ejection (CME) event traced in the data of PSR J1022+1001, and reports evidence for a potential mode-changing event in PSR J2145 - 0750. By contrasting these two cases, we show that DM fluctuations due to CME interacions and intrinsic mode-changing events produce distinct observational signatures, enabling a physically informed classification of scientific outliers in PTA datasets. Extending the analyses presented here to the full sample of InPTA-DR2 pulsars is expected to reveal additional CME events, and possible mode-changing events. Such detections will not only improve our understanding of solar and pulsar magnetospheric plasma interactions but will also enable more accurate modelling of DM variations, leading to improved pulsar timing solutions, which are crucial for high-precision Pulsar Timing Array (PTA) science.
{"title":"Effects of coronal mass ejection on PSR J1022+1001 and possible mode change of PSR J2145 - 0750 in the InPTA DR2","authors":"Shaswata Chowdhury , M.A. Krishnakumar , Manjari Bagchi , Bhal Chandra Joshi , Nobleson K , Jibin Jose , Shantanu Desai , Manpreet Singh , Vaishnavi Vyasraj , Kuldeep Meena , Amarnath , Manoneeta Chakraborty , Shubham Kala , Debabrata Deb , Zenia Zuraiq , Arul Pandian B , Neelam Dhanda Batra , Churchil Dwivedi , Sushovan Mondal , Avinash Kumar Paladi , Kunjal Vara","doi":"10.1016/j.jheap.2025.100547","DOIUrl":"10.1016/j.jheap.2025.100547","url":null,"abstract":"<div><div>The Indian Pulsar Timing Array (InPTA) has recently published its second data release (DR2), comprising the timing analysis of seven years of data on 27 millisecond pulsars (MSPs), observed simultaneously in the 300 - 500 MHz (band 3) and 1260 - 1460 MHz (band 5), using the upgraded Giant Metrewave Radio Telescope (uGMRT). The low-frequency data, particularly in band 3, is highly sensitive to propagation effects such as dispersion measure (DM) fluctuations, which can be imprints of some astrophysical phenomena (scientific outliers). Here, we analyze the two outliers of possible astrophysical origin coming from the band 3 DM time series of two pulsars: PSR J1022+1001, with an ecliptic latitude of <span><math><mrow><mo>−</mo><mn>0</mn><mo>.</mo><msup><mn>06</mn><mo>∘</mo></msup></mrow></math></span>, and PSR J2145 - 0750, one of the brightest MSPs, with multi-component profile morphology. Our study reveals compelling evidence for a coronal mass ejection (CME) event traced in the data of PSR J1022+1001, and reports evidence for a potential mode-changing event in PSR J2145 - 0750. By contrasting these two cases, we show that DM fluctuations due to CME interacions and intrinsic mode-changing events produce distinct observational signatures, enabling a physically informed classification of scientific outliers in PTA datasets. Extending the analyses presented here to the full sample of InPTA-DR2 pulsars is expected to reveal additional CME events, and possible mode-changing events. Such detections will not only improve our understanding of solar and pulsar magnetospheric plasma interactions but will also enable more accurate modelling of DM variations, leading to improved pulsar timing solutions, which are crucial for high-precision Pulsar Timing Array (PTA) science.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100547"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976542","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 : 2026-03-01Epub Date: 2026-01-07DOI: 10.1016/j.jheap.2026.100550
A. Bukhari , G. Abbas , Tao Zhu
Accretion disks around compact astrophysical objects provide an essential framework for examining the nature of strong gravitational fields and exploring possible manifestations of quantum gravity. In this paper, we examine the structural and radiative features of a geometrically thin disk encircling a quantum–corrected Reissner–Nordström black hole (QCRN–BH), where the spacetime geometry is influenced by both the electric charge Q and the quantum correction parameter ω. Employing the geodesic equations and the analysis of the effective potential, we obtain the criteria for stable circular motion, locate the innermost stable circular orbit (ISCO), and evaluate the corresponding specific energy, angular momentum, and angular velocity of the disk matter. The results demonstrate that higher values of either Q or ω drive the ISCO toward smaller radii, reduce the energy per unit mass, and enhance the overall radiative efficiency. The modified distributions of the flux, temperature, and luminosity suggest that quantum effects increase the conversion of gravitational energy in the inner disk region. This work highlights, for the first time, the combined impact of Q and ω on disk dynamics, stability, and emission properties, providing phenomenological perspective for distinguishing quantum–corrected black holes from classical ones.
{"title":"Orbital structure and radiative behavior of accretion disks around quantum-corrected charged black holes","authors":"A. Bukhari , G. Abbas , Tao Zhu","doi":"10.1016/j.jheap.2026.100550","DOIUrl":"10.1016/j.jheap.2026.100550","url":null,"abstract":"<div><div>Accretion disks around compact astrophysical objects provide an essential framework for examining the nature of strong gravitational fields and exploring possible manifestations of quantum gravity. In this paper, we examine the structural and radiative features of a geometrically thin disk encircling a quantum–corrected Reissner–Nordström black hole (QCRN–BH), where the spacetime geometry is influenced by both the electric charge <em>Q</em> and the quantum correction parameter <em>ω</em>. Employing the geodesic equations and the analysis of the effective potential, we obtain the criteria for stable circular motion, locate the innermost stable circular orbit (ISCO), and evaluate the corresponding specific energy, angular momentum, and angular velocity of the disk matter. The results demonstrate that higher values of either <em>Q</em> or <em>ω</em> drive the ISCO toward smaller radii, reduce the energy per unit mass, and enhance the overall radiative efficiency. The modified distributions of the flux, temperature, and luminosity suggest that quantum effects increase the conversion of gravitational energy in the inner disk region. This work highlights, for the first time, the combined impact of <em>Q</em> and <em>ω</em> on disk dynamics, stability, and emission properties, providing phenomenological perspective for distinguishing quantum–corrected black holes from classical ones.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100550"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976543","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 : 2026-03-01Epub Date: 2025-12-24DOI: 10.1016/j.jheap.2025.100540
Xiao-Xiong Zeng , Chen-Yu Yang , Muhammad Israr Aslam , Rabia Saleem
In this study, we have considered the Kerr-like black hole (BH) model in Horndeski gravity and analyse the visual characteristics of shadow images under two illumination models, such as a celestial light source and a thin accretion disk. To capture the BH shadow images, we utilize a recent fisheye camera model and ray-tracing procedures. In this view, we carefully addressed the influence of the spin parameter a and the hair parameter h on the BH shadow images. The results indicate that for smaller values of h, the BH shadow contours shift noticeably towards the right side of the screen, while for larger values of h, the nearly circular shadow gradually deforms into a possible flatness profile. For a celestial light source, the larger values of h lead to a reduction in the corresponding radius of the photon ring, while the space-dragging effect becomes more pronounced with increasing a. We further discuss the distinctive characteristics of images observed in both prograde and retrograde accretion disk scenarios. The results reveal that variations in h significantly affect both the inner shadow and the resulting Einstein ring. Subsequently, we also discussed the distinct features of red-shift configurations on the disk for both direct and lensed images, which are closely related to the accretion flow and the relevant parameters. We also attempt to use the recent observational data from M87* and Sgr A* and constraint the hair parameter h, the results are consistent and promising.
{"title":"Probing Horndeski gravity via Kerr black hole: Insights from thin accretion disks and shadows with EHT observations","authors":"Xiao-Xiong Zeng , Chen-Yu Yang , Muhammad Israr Aslam , Rabia Saleem","doi":"10.1016/j.jheap.2025.100540","DOIUrl":"10.1016/j.jheap.2025.100540","url":null,"abstract":"<div><div>In this study, we have considered the Kerr-like black hole (BH) model in Horndeski gravity and analyse the visual characteristics of shadow images under two illumination models, such as a celestial light source and a thin accretion disk. To capture the BH shadow images, we utilize a recent fisheye camera model and ray-tracing procedures. In this view, we carefully addressed the influence of the spin parameter <em>a</em> and the hair parameter <em>h</em> on the BH shadow images. The results indicate that for smaller values of <em>h</em>, the BH shadow contours shift noticeably towards the right side of the screen, while for larger values of <em>h</em>, the nearly circular shadow gradually deforms into a possible flatness profile. For a celestial light source, the larger values of <em>h</em> lead to a reduction in the corresponding radius of the photon ring, while the space-dragging effect becomes more pronounced with increasing <em>a</em>. We further discuss the distinctive characteristics of images observed in both prograde and retrograde accretion disk scenarios. The results reveal that variations in <em>h</em> significantly affect both the inner shadow and the resulting Einstein ring. Subsequently, we also discussed the distinct features of red-shift configurations on the disk for both direct and lensed images, which are closely related to the accretion flow and the relevant parameters. We also attempt to use the recent observational data from M87* and Sgr <em>A</em>* and constraint the hair parameter <em>h</em>, the results are consistent and promising.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100540"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884291","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 : 2026-03-01Epub Date: 2026-01-10DOI: 10.1016/j.jheap.2026.100552
M. Reshma , C.S. Stalin , Amit Kumar Mandal , Abhijit Kayal , S.B. Gudennavar , Prajwel Joseph
Active galactic nuclei are known to exhibit flux variations across the entire electromagnetic spectrum. Among these, correlations between UV/optical and X-ray flux variations serve as a key diagnostics for understanding the physical connection between the accretion disk and the corona. In this work, we present the results of analysis of ultraviolet (UV) and X-ray flux variations in the narrow line Seyfert 1 galaxy Mrk 1044. Simultaneous observations in the far-UV band (FUV: 1300 - 1800 Å) and the X-ray band (0.5 - 7 keV) obtained during 31 August - 8 September 2018 with the Ultraviolet Imaging Telescope and the Soft X-ray Telescope onboard AstroSat were used for this study. Significant flux variability was detected in both FUV and X-ray bands. The fractional root mean square variability amplitude (Fvar) was found to be 0.036 ± 0.001 in the FUV band and 0.384 ± 0.004 in the X-ray band. To explore potential time lag between the two bands, cross-correlation analysis was performed using both the interpolated cross-correlation function (ICCF) and just another vehicle for estimating lags in nuclei (JAVELIN) methods. Results from both approaches are consistent within 2σ uncertainty, indicating that X-ray variations lead the FUV variations, with measured lags of 2.25 ± 0.05 days (ICCF) and days (JAVELIN). This is the first detection of a time delay between UV and X-ray variations in Mrk 1044. The observed UV lag supports the disk reprocessing scenario, wherein X-ray emission from the corona irradiates the accretion disk, driving the observed UV variability.
{"title":"Detection of time delay between UV and X-ray variability in Mrk 1044 using AstroSat observations","authors":"M. Reshma , C.S. Stalin , Amit Kumar Mandal , Abhijit Kayal , S.B. Gudennavar , Prajwel Joseph","doi":"10.1016/j.jheap.2026.100552","DOIUrl":"10.1016/j.jheap.2026.100552","url":null,"abstract":"<div><div>Active galactic nuclei are known to exhibit flux variations across the entire electromagnetic spectrum. Among these, correlations between UV/optical and X-ray flux variations serve as a key diagnostics for understanding the physical connection between the accretion disk and the corona. In this work, we present the results of analysis of ultraviolet (UV) and X-ray flux variations in the narrow line Seyfert 1 galaxy Mrk 1044. Simultaneous observations in the far-UV band (FUV: 1300 - 1800 Å) and the X-ray band (0.5 - 7 keV) obtained during 31 August - 8 September 2018 with the Ultraviolet Imaging Telescope and the Soft X-ray Telescope onboard <em>AstroSat</em> were used for this study. Significant flux variability was detected in both FUV and X-ray bands. The fractional root mean square variability amplitude (<em>F</em><sub>var</sub>) was found to be 0.036 ± 0.001 in the FUV band and 0.384 ± 0.004 in the X-ray band. To explore potential time lag between the two bands, cross-correlation analysis was performed using both the interpolated cross-correlation function (ICCF) and just another vehicle for estimating lags in nuclei (JAVELIN) methods. Results from both approaches are consistent within 2<em>σ</em> uncertainty, indicating that X-ray variations lead the FUV variations, with measured lags of 2.25 ± 0.05 days (ICCF) and <span><math><mrow><mn>2</mn><mo>.</mo><msubsup><mn>35</mn><mrow><mo>−</mo><mn>0.01</mn></mrow><mrow><mo>+</mo><mn>0.02</mn></mrow></msubsup></mrow></math></span> days (JAVELIN). This is the first detection of a time delay between UV and X-ray variations in Mrk 1044. The observed UV lag supports the disk reprocessing scenario, wherein X-ray emission from the corona irradiates the accretion disk, driving the observed UV variability.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100552"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976509","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 : 2026-03-01Epub Date: 2026-01-08DOI: 10.1016/j.jheap.2026.100551
Muhammad Israr Aslam , Rabia Saleem , Chen-Yu Yang , Xiao-Xiong Zeng
Based on two distinct thick accretion flow disk models, such as a phenomenological RIAF-like model and an analytical Hou disk model, we investigate the impact of relevant parameters on the visual characteristics of the Schwarzschild black hole (BH) surrounded by perfect fluid dark matter (PFDM). We impose a general relativistic radiative transfer equation to determine the synchrotron emission from thermal electrons and generate horizon-scale images. In the RIAF-like model, we notice that the corresponding photon ring and central dark region are expanded with the aid of the PFDM parameter η, with brightness asymmetries originating at higher inclination angles and closely tied to flow dynamics and emission anisotropy. The fundamental difference between isotropic and anisotropic radiation is that anisotropy introduces vertical distortions in the higher-order images, resulting in an elliptical appearance. For the Hou disk model, the observed images produce narrower rings and dark interiors, while polarization patterns trace the brightness distribution and changes with the variations of the inclination angle and PFDM parameter η, which reflects the spacetime signature. All these results indicate that the observed intensity and polarization characteristics in the framework of thick disk models may serve as valuable probes of underlying spacetime geometry and the accretion-dynamics close to the horizon.
{"title":"Imprints of dark matter on the shadow and polarization images of a black hole illuminated by various thick disks","authors":"Muhammad Israr Aslam , Rabia Saleem , Chen-Yu Yang , Xiao-Xiong Zeng","doi":"10.1016/j.jheap.2026.100551","DOIUrl":"10.1016/j.jheap.2026.100551","url":null,"abstract":"<div><div>Based on two distinct thick accretion flow disk models, such as a phenomenological RIAF-like model and an analytical Hou disk model, we investigate the impact of relevant parameters on the visual characteristics of the Schwarzschild black hole (BH) surrounded by perfect fluid dark matter (PFDM). We impose a general relativistic radiative transfer equation to determine the synchrotron emission from thermal electrons and generate horizon-scale images. In the RIAF-like model, we notice that the corresponding photon ring and central dark region are expanded with the aid of the PFDM parameter <em>η</em>, with brightness asymmetries originating at higher inclination angles and closely tied to flow dynamics and emission anisotropy. The fundamental difference between isotropic and anisotropic radiation is that anisotropy introduces vertical distortions in the higher-order images, resulting in an elliptical appearance. For the Hou disk model, the observed images produce narrower rings and dark interiors, while polarization patterns trace the brightness distribution and changes with the variations of the inclination angle and PFDM parameter <em>η</em>, which reflects the spacetime signature. All these results indicate that the observed intensity and polarization characteristics in the framework of thick disk models may serve as valuable probes of underlying spacetime geometry and the accretion-dynamics close to the horizon.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100551"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976520","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 : 2026-03-01Epub Date: 2025-11-21DOI: 10.1016/j.jheap.2025.100516
M. Koussour , O. Donmez , S. Bekov , A. Altaibayeva , A. Saginbay , S. Muminov , J. Rayimbaev
<div><div>We introduce and constrain a new parameterization for the dark energy equation of state, the b-CPL model, defined as <span><math><mrow><msub><mi>ω</mi><mrow><mi>b</mi><mtext>-CPL</mtext></mrow></msub><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow><mo>=</mo><msub><mi>ω</mi><mn>0</mn></msub><mo>+</mo><msub><mi>ω</mi><mn>1</mn></msub><mfrac><mi>z</mi><mrow><mn>1</mn><mo>+</mo><mi>b</mi><mi>z</mi></mrow></mfrac></mrow></math></span>, which extends the standard CPL framework by including a parameter <em>b</em>. This additional degree of freedom provides enhanced flexibility to capture potential deviations from standard dynamical dark energy behavior, while reducing to CPL for <span><math><mrow><mi>b</mi><mo>=</mo><mn>1</mn></mrow></math></span> and to ΛCDM in specific limits. Notably, the b-CPL parameterization remains finite at future times, avoiding divergences. Using a combined dataset of cosmic chronometers, PantheonPlus Type Ia supernovae, and DESI baryon acoustic oscillations, we perform a Markov Chain Monte Carlo analysis to constrain the cosmological parameters for the b-CPL, CPL, and ΛCDM models. The b-CPL model yields a more negative present-day equation of state (<span><math><mrow><msub><mi>ω</mi><mn>0</mn></msub><mo>=</mo><mo>−</mo><mn>1</mn><mo>.</mo><msubsup><mn>12</mn><mrow><mo>−</mo><mn>0.20</mn></mrow><mrow><mo>+</mo><mn>0.31</mn></mrow></msubsup></mrow></math></span>) and a higher matter density (<span><math><mrow><msubsup><mstyle><mi>Ω</mi></mstyle><mi>m</mi><mn>0</mn></msubsup><mo>=</mo><mn>0</mn><mo>.</mo><msubsup><mn>332</mn><mrow><mo>−</mo><mn>0.049</mn></mrow><mrow><mo>+</mo><mn>0.065</mn></mrow></msubsup></mrow></math></span>) compared to CPL and ΛCDM. Model selection statistics based on the reduced chi-square, AIC, and BIC indicate that b-CPL is strongly preferred, showing decisive evidence over ΛCDM (<span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>AIC</mtext><mo>=</mo><mo>−</mo><mn>41.83</mn></mrow></math></span>, <span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>BIC</mtext><mo>=</mo><mo>−</mo><mn>30.91</mn></mrow></math></span>) and significant improvement over CPL (<span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>AIC</mtext><mo>=</mo><mo>−</mo><mn>26.05</mn></mrow></math></span>, <span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>BIC</mtext><mo>=</mo><mo>−</mo><mn>9.66</mn></mrow></math></span>). Physically, the b-CPL model exhibits a mild redshift evolution of the EoS parameter and tends to remain in the phantom regime (<span><math><mrow><msub><mi>ω</mi><mn>0</mn></msub><mo><</mo><mo>−</mo><mn>1</mn></mrow></math></span>) at present, although within 68 % confidence level, the quintessence region (<span><math><mrow><msub><mi>ω</mi><mn>0</mn></msub><mo>></mo><mo>−</mo><mn>1</mn></mrow></math></span>) is still allowed. It predicts the strongest present-day acceleration (<span><math><mrow><msub><mi>q</mi><mn>0</mn></msub><mo>=</mo><mo>−</mo><mn>0.62</mn><mo>±</mo><mn>0.27</mn></mrow></math></span>), and
{"title":"Testing the b-CPL dynamical dark energy model with recent cosmological data","authors":"M. Koussour , O. Donmez , S. Bekov , A. Altaibayeva , A. Saginbay , S. Muminov , J. Rayimbaev","doi":"10.1016/j.jheap.2025.100516","DOIUrl":"10.1016/j.jheap.2025.100516","url":null,"abstract":"<div><div>We introduce and constrain a new parameterization for the dark energy equation of state, the b-CPL model, defined as <span><math><mrow><msub><mi>ω</mi><mrow><mi>b</mi><mtext>-CPL</mtext></mrow></msub><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow><mo>=</mo><msub><mi>ω</mi><mn>0</mn></msub><mo>+</mo><msub><mi>ω</mi><mn>1</mn></msub><mfrac><mi>z</mi><mrow><mn>1</mn><mo>+</mo><mi>b</mi><mi>z</mi></mrow></mfrac></mrow></math></span>, which extends the standard CPL framework by including a parameter <em>b</em>. This additional degree of freedom provides enhanced flexibility to capture potential deviations from standard dynamical dark energy behavior, while reducing to CPL for <span><math><mrow><mi>b</mi><mo>=</mo><mn>1</mn></mrow></math></span> and to ΛCDM in specific limits. Notably, the b-CPL parameterization remains finite at future times, avoiding divergences. Using a combined dataset of cosmic chronometers, PantheonPlus Type Ia supernovae, and DESI baryon acoustic oscillations, we perform a Markov Chain Monte Carlo analysis to constrain the cosmological parameters for the b-CPL, CPL, and ΛCDM models. The b-CPL model yields a more negative present-day equation of state (<span><math><mrow><msub><mi>ω</mi><mn>0</mn></msub><mo>=</mo><mo>−</mo><mn>1</mn><mo>.</mo><msubsup><mn>12</mn><mrow><mo>−</mo><mn>0.20</mn></mrow><mrow><mo>+</mo><mn>0.31</mn></mrow></msubsup></mrow></math></span>) and a higher matter density (<span><math><mrow><msubsup><mstyle><mi>Ω</mi></mstyle><mi>m</mi><mn>0</mn></msubsup><mo>=</mo><mn>0</mn><mo>.</mo><msubsup><mn>332</mn><mrow><mo>−</mo><mn>0.049</mn></mrow><mrow><mo>+</mo><mn>0.065</mn></mrow></msubsup></mrow></math></span>) compared to CPL and ΛCDM. Model selection statistics based on the reduced chi-square, AIC, and BIC indicate that b-CPL is strongly preferred, showing decisive evidence over ΛCDM (<span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>AIC</mtext><mo>=</mo><mo>−</mo><mn>41.83</mn></mrow></math></span>, <span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>BIC</mtext><mo>=</mo><mo>−</mo><mn>30.91</mn></mrow></math></span>) and significant improvement over CPL (<span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>AIC</mtext><mo>=</mo><mo>−</mo><mn>26.05</mn></mrow></math></span>, <span><math><mrow><mstyle><mi>Δ</mi></mstyle><mtext>BIC</mtext><mo>=</mo><mo>−</mo><mn>9.66</mn></mrow></math></span>). Physically, the b-CPL model exhibits a mild redshift evolution of the EoS parameter and tends to remain in the phantom regime (<span><math><mrow><msub><mi>ω</mi><mn>0</mn></msub><mo><</mo><mo>−</mo><mn>1</mn></mrow></math></span>) at present, although within 68 % confidence level, the quintessence region (<span><math><mrow><msub><mi>ω</mi><mn>0</mn></msub><mo>></mo><mo>−</mo><mn>1</mn></mrow></math></span>) is still allowed. It predicts the strongest present-day acceleration (<span><math><mrow><msub><mi>q</mi><mn>0</mn></msub><mo>=</mo><mo>−</mo><mn>0.62</mn><mo>±</mo><mn>0.27</mn></mrow></math></span>), and ","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100516"},"PeriodicalIF":10.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145610151","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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