Pub 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":"2026-01-08","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 : 2026-01-07DOI: 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":"2026-01-07","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 : 2026-01-06DOI: 10.1016/j.jheap.2026.100549
Debosi Mondal, Biswajit Pandey, Amit Mondal
The cosmological principle, asserting large-scale homogeneity and isotropy, underpins the standard model of cosmology. Testing its validity using independent astronomical probes remains crucial for understanding the global structure of the Universe. We investigate the angular distribution of Gamma-Ray Bursts (GRBs) using two of the most comprehensive all-sky datasets available, the BATSE (CGRO) and Fermi GBM catalogs, to test the isotropy of the GRB sky at large angular scales. We perform spherical harmonic decomposition of the GRB sky maps and estimate the dipole and quadrupole amplitudes. Statistical significance is evaluated by comparing the observed multipole amplitudes against distributions derived from 500 Monte Carlo realizations of isotropic skies. Our results show that the observed dipole amplitudes for both BATSE and Fermi GBM datasets lie within the 1σ region of their respective null distributions. However, the quadrupole amplitude in the raw, uncorrected BATSE and Fermi GBM skies appears elevated at 3.7σ and 3.0σ, respectively. After incorporating the BATSE sky exposure function, this apparent quadrupole anisotropy vanishes, indicating that instrumental non-uniformities fully account for the signal in that case. Owing to the absence of a publicly available full-sky exposure model for Fermi GBM, the Fermi analysis is restricted to the raw sky distribution. Our method’s reliability is validated through controlled simulations, which show it can detect the injected dipoles in BATSE-sized isotropic skies. These findings reinforce the statistical isotropy of the GRB sky and underscore the importance of accurate exposure corrections in cosmological anisotropy analyses.
{"title":"Probing cosmic isotropy with gamma-ray bursts: A dipole and quadrupole analysis of BATSE and Fermi GBM data","authors":"Debosi Mondal, Biswajit Pandey, Amit Mondal","doi":"10.1016/j.jheap.2026.100549","DOIUrl":"10.1016/j.jheap.2026.100549","url":null,"abstract":"<div><div>The cosmological principle, asserting large-scale homogeneity and isotropy, underpins the standard model of cosmology. Testing its validity using independent astronomical probes remains crucial for understanding the global structure of the Universe. We investigate the angular distribution of Gamma-Ray Bursts (GRBs) using two of the most comprehensive all-sky datasets available, the BATSE (CGRO) and Fermi GBM catalogs, to test the isotropy of the GRB sky at large angular scales. We perform spherical harmonic decomposition of the GRB sky maps and estimate the dipole and quadrupole amplitudes. Statistical significance is evaluated by comparing the observed multipole amplitudes against distributions derived from 500 Monte Carlo realizations of isotropic skies. Our results show that the observed dipole amplitudes for both BATSE and Fermi GBM datasets lie within the 1<em>σ</em> region of their respective null distributions. However, the quadrupole amplitude in the raw, uncorrected BATSE and Fermi GBM skies appears elevated at 3.7<em>σ</em> and 3.0<em>σ</em>, respectively. After incorporating the BATSE sky exposure function, this apparent quadrupole anisotropy vanishes, indicating that instrumental non-uniformities fully account for the signal in that case. Owing to the absence of a publicly available full-sky exposure model for Fermi GBM, the Fermi analysis is restricted to the raw sky distribution. Our method’s reliability is validated through controlled simulations, which show it can detect the injected dipoles in BATSE-sized isotropic skies. These findings reinforce the statistical isotropy of the GRB sky and underscore the importance of accurate exposure corrections in cosmological anisotropy analyses.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100549"},"PeriodicalIF":10.5,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938336","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 : 2026-01-02DOI: 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":"2026-01-02","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 : 2026-01-01DOI: 10.1016/j.jheap.2025.100546
André LeClair
<div><div>We explore the idea that quantum vacuum energy <em>ρ</em><sub>vac</sub>, as computed in flat Minkowski space, is at the origin of Gravity. We formulate a gravitational version of the electromagnetic Casimir effect, and provide an argument for how gravity can arise from <em>ρ</em><sub>vac</sub> by showing how Einstein’s field equations emerge in the form of Friedmann’s equations. This leads to the idea that Newton’s constant <em>G<sub>N</sub></em> is environmental, namely it depends on the total mass-energy of the universe <span><math><msub><mrow><mi>M</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></math></span> and its size <span><math><msub><mrow><mi>R</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></math></span>, with <span><math><mrow><msub><mi>G</mi><mi>N</mi></msub><mo>=</mo><msup><mi>c</mi><mn>2</mn></msup><msub><mrow><mi>R</mi></mrow><mstyle><mi>∞</mi></mstyle></msub><mo>/</mo><mn>2</mn><msub><mrow><mi>M</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></mrow></math></span>. This leads to a new interpretation of the Gibbons-Hawking entropy of de Sitter space, and also the Bekenstein-Hawking entropy for black holes, wherein the quantum information “bits” are simply quantized massless particles at the horizon with wavelength <span><math><mrow><mi>λ</mi><mo>=</mo><mn>2</mn><mi>π</mi><msub><mrow><mi>R</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></mrow></math></span>. We assume a recently proposed and well-motivated formula for <span><math><mrow><msub><mi>ρ</mi><mrow><mrow><mi>v</mi></mrow><mi>a</mi><mi>c</mi></mrow></msub><mo>∝</mo><msubsup><mi>m</mi><mrow><mrow><mi>z</mi></mrow></mrow><mn>4</mn></msubsup><mo>/</mo><mi>g</mi></mrow></math></span>, where <em>m</em><sub>z</sub> is the mass of the lightest particle, and <span><math><mi>g</mi></math></span> is a marginally irrelevant coupling. This leads to an effective, induced RG flow for Newton’s constant <em>G<sub>N</sub></em> as a function of an energy scale, which indicates that <em>G<sub>N</sub> decreases</em> at higher energies until it reaches a Landau pole at a minimal value of the cosmological scale factor <em>a</em>(<em>t</em>) > <em>a</em><sub>min</sub>, thus avoiding the usual geometric curvature singularity at <span><math><mrow><mi>a</mi><mo>=</mo><mn>0</mn></mrow></math></span>. The solution to the scale factor satisfies an interesting symmetry between the far past and far future due to <span><math><mrow><mi>a</mi><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>=</mo><mi>a</mi><mrow><mo>(</mo><mo>−</mo><mi>t</mi><mo>+</mo><mn>2</mn><msub><mi>t</mi><mrow><mrow><mi>m</mi></mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span>, where <span><math><mrow><mi>a</mi><mrow><mo>(</mo><msub><mi>t</mi><mrow><mrow><mi>m</mi></mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>)</mo></mrow><mo>=</mo><msub><mi>a</mi><mrow><mrow><mi>m</mi></mrow><mi>i</mi><mi>n</mi></mrow></msub></mrow></math></span>. We propose that this energy scale dependent <em>G<sub>N</sub></em> can expl
{"title":"Quantum vacuum energy as the origin of gravity","authors":"André LeClair","doi":"10.1016/j.jheap.2025.100546","DOIUrl":"10.1016/j.jheap.2025.100546","url":null,"abstract":"<div><div>We explore the idea that quantum vacuum energy <em>ρ</em><sub>vac</sub>, as computed in flat Minkowski space, is at the origin of Gravity. We formulate a gravitational version of the electromagnetic Casimir effect, and provide an argument for how gravity can arise from <em>ρ</em><sub>vac</sub> by showing how Einstein’s field equations emerge in the form of Friedmann’s equations. This leads to the idea that Newton’s constant <em>G<sub>N</sub></em> is environmental, namely it depends on the total mass-energy of the universe <span><math><msub><mrow><mi>M</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></math></span> and its size <span><math><msub><mrow><mi>R</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></math></span>, with <span><math><mrow><msub><mi>G</mi><mi>N</mi></msub><mo>=</mo><msup><mi>c</mi><mn>2</mn></msup><msub><mrow><mi>R</mi></mrow><mstyle><mi>∞</mi></mstyle></msub><mo>/</mo><mn>2</mn><msub><mrow><mi>M</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></mrow></math></span>. This leads to a new interpretation of the Gibbons-Hawking entropy of de Sitter space, and also the Bekenstein-Hawking entropy for black holes, wherein the quantum information “bits” are simply quantized massless particles at the horizon with wavelength <span><math><mrow><mi>λ</mi><mo>=</mo><mn>2</mn><mi>π</mi><msub><mrow><mi>R</mi></mrow><mstyle><mi>∞</mi></mstyle></msub></mrow></math></span>. We assume a recently proposed and well-motivated formula for <span><math><mrow><msub><mi>ρ</mi><mrow><mrow><mi>v</mi></mrow><mi>a</mi><mi>c</mi></mrow></msub><mo>∝</mo><msubsup><mi>m</mi><mrow><mrow><mi>z</mi></mrow></mrow><mn>4</mn></msubsup><mo>/</mo><mi>g</mi></mrow></math></span>, where <em>m</em><sub>z</sub> is the mass of the lightest particle, and <span><math><mi>g</mi></math></span> is a marginally irrelevant coupling. This leads to an effective, induced RG flow for Newton’s constant <em>G<sub>N</sub></em> as a function of an energy scale, which indicates that <em>G<sub>N</sub> decreases</em> at higher energies until it reaches a Landau pole at a minimal value of the cosmological scale factor <em>a</em>(<em>t</em>) > <em>a</em><sub>min</sub>, thus avoiding the usual geometric curvature singularity at <span><math><mrow><mi>a</mi><mo>=</mo><mn>0</mn></mrow></math></span>. The solution to the scale factor satisfies an interesting symmetry between the far past and far future due to <span><math><mrow><mi>a</mi><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>=</mo><mi>a</mi><mrow><mo>(</mo><mo>−</mo><mi>t</mi><mo>+</mo><mn>2</mn><msub><mi>t</mi><mrow><mrow><mi>m</mi></mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span>, where <span><math><mrow><mi>a</mi><mrow><mo>(</mo><msub><mi>t</mi><mrow><mrow><mi>m</mi></mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>)</mo></mrow><mo>=</mo><msub><mi>a</mi><mrow><mrow><mi>m</mi></mrow><mi>i</mi><mi>n</mi></mrow></msub></mrow></math></span>. We propose that this energy scale dependent <em>G<sub>N</sub></em> can expl","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100546"},"PeriodicalIF":10.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976541","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 : 2025-12-31DOI: 10.1016/j.jheap.2025.100545
Mahasweta Bhattacharya , Aditya S. Mondal , Biplab Raychaudhuri , Gulab C. Dewangan
We report on the results obtained by the analysis of persistent and type-I thermonuclear X-ray burst emission observed from the periodic burster 4U 1323-62. These analyses are based on the NuSTAR observation performed on 2024 August 7, for a total exposure of around 90 ks. The persistent emission is well described by an absorbed thermal Comptonization model. An absorption edge is also detected at an energy of ∼ 7.42 keV, which indicates the presence of absorbing material in the vicinity of this system. Six bursts have been observed during this observation, wherein we find the burst recurrence time to be 4.52 ± 0.32 hr. All the bursts exhibit the characteristics of a sharp rise and exponential decay. We perform the time-resolved spectroscopy of the burst spectra described by a model consisting of thermal emission from the neutron star surface and a varying persistent emission component to study the evolution of burst parameters. The enhancement of the persistent emission during burst exposure is characterized by the scaling parameter fa, which reflects the increasing strength of the burst-disc interaction with burst intensity, likely driven by Poynting-Robertson drag. The spectral analysis of bursts estimate the average apparent blackbody emitting radius of the neutron star to lie within 1.5-3.5 km. The ignition depths computed from the burst parameters indicate short Type-I thermonuclear bursts from a mixed hydrogen-helium fuel layer.
{"title":"Exploring the spectral characteristics of the periodic burster 4U 1323-62: Type-I X-ray burst and persistent emission","authors":"Mahasweta Bhattacharya , Aditya S. Mondal , Biplab Raychaudhuri , Gulab C. Dewangan","doi":"10.1016/j.jheap.2025.100545","DOIUrl":"10.1016/j.jheap.2025.100545","url":null,"abstract":"<div><div>We report on the results obtained by the analysis of persistent and type-I thermonuclear X-ray burst emission observed from the periodic burster 4U 1323-62. These analyses are based on the <em>NuSTAR</em> observation performed on 2024 August 7, for a total exposure of around 90 ks. The persistent emission is well described by an absorbed thermal Comptonization model. An absorption edge is also detected at an energy of ∼ 7.42 keV, which indicates the presence of absorbing material in the vicinity of this system. Six bursts have been observed during this observation, wherein we find the burst recurrence time to be 4.52 ± 0.32 hr. All the bursts exhibit the characteristics of a sharp rise and exponential decay. We perform the time-resolved spectroscopy of the burst spectra described by a model consisting of thermal emission from the neutron star surface and a varying persistent emission component to study the evolution of burst parameters. The enhancement of the persistent emission during burst exposure is characterized by the scaling parameter <em>f</em><sub>a</sub>, which reflects the increasing strength of the burst-disc interaction with burst intensity, likely driven by Poynting-Robertson drag. The spectral analysis of bursts estimate the average apparent blackbody emitting radius of the neutron star to lie within 1.5-3.5 km. The ignition depths computed from the burst parameters indicate short Type-I thermonuclear bursts from a mixed hydrogen-helium fuel layer.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100545"},"PeriodicalIF":10.5,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938335","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}
We investigate particle dynamics and observational signatures in the spacetime of a charged black hole arising from effective quantum gravity. Starting from the geodesic motion of neutral particles, we derive the equations of motion and analyze the impact of quantum corrections on the effective potential, the stability of circular orbits, and the innermost stable circular orbit (ISCO). The results show that quantum effects can significantly shift the ISCO radius and alter orbital stability compared to the Schwarzschild case. The analysis is further extended to the motion of charged particles in the presence of an external magnetic field, revealing strong dependencies on the sign and magnitude of the particle’s charge. The Lorentz force is found to modify the ISCO location and allow for trapping or escape trajectories, highlighting the importance of electromagnetic interactions in realistic astrophysical environments. Finally, by performing a MCMC fitting to the orbital motion of the S2 star around Sgr A*, we constrain the black hole parameters and find them consistent with current observational bounds. Our results suggest that quantum corrected charged black holes can imprint measurable effects on particle dynamics, offering potential tests of alternative gravity models through high-precision astrophysical observations.
我们研究了由有效量子引力引起的带电黑洞的粒子动力学和观测特征。从中性粒子的测地线运动出发，推导了运动方程，分析了量子修正对有效势、圆轨道稳定性和最内层稳定圆轨道（ISCO）的影响。结果表明，与史瓦西情况相比，量子效应可以显著改变ISCO半径并改变轨道稳定性。分析进一步扩展到带电粒子在外部磁场存在下的运动，揭示了对粒子电荷的符号和大小的强烈依赖。发现洛伦兹力可以改变ISCO的位置，并允许捕获或逃逸轨迹，突出了电磁相互作用在现实天体物理环境中的重要性。最后，通过对Sgr a *周围S2恒星的轨道运动进行MCMC拟合，我们约束了黑洞参数，并发现它们与当前的观测范围一致。我们的研究结果表明，量子修正带电黑洞可以对粒子动力学产生可测量的影响，通过高精度天体物理观测为替代引力模型提供了潜在的测试。
{"title":"Testing quantum-corrected black hole through particle dynamics and S2 star observations","authors":"Bakhodirkhon Saidov , Bakhtiyor Narzilloev , Ahmadjon Abdujabbarov , Ibrar Hussain , Bobomurat Ahmedov , Chengxun Yuan , Chen Zhou","doi":"10.1016/j.jheap.2025.100543","DOIUrl":"10.1016/j.jheap.2025.100543","url":null,"abstract":"<div><div>We investigate particle dynamics and observational signatures in the spacetime of a charged black hole arising from effective quantum gravity. Starting from the geodesic motion of neutral particles, we derive the equations of motion and analyze the impact of quantum corrections on the effective potential, the stability of circular orbits, and the innermost stable circular orbit (ISCO). The results show that quantum effects can significantly shift the ISCO radius and alter orbital stability compared to the Schwarzschild case. The analysis is further extended to the motion of charged particles in the presence of an external magnetic field, revealing strong dependencies on the sign and magnitude of the particle’s charge. The Lorentz force is found to modify the ISCO location and allow for trapping or escape trajectories, highlighting the importance of electromagnetic interactions in realistic astrophysical environments. Finally, by performing a MCMC fitting to the orbital motion of the S2 star around Sgr A*, we constrain the black hole parameters and find them consistent with current observational bounds. Our results suggest that quantum corrected charged black holes can imprint measurable effects on particle dynamics, offering potential tests of alternative gravity models through high-precision astrophysical observations.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100543"},"PeriodicalIF":10.5,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976508","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 : 2025-12-29DOI: 10.1016/j.jheap.2025.100536
Shang Li
This study uses approximately 17 years of Fermi-LAT data to search for γ-ray emission from 45 Milky Way dwarf spheroidal galaxies (dSphs, including candidates). No significant ( > 5σ) γ-ray signal is found in the scenarios of dark matter annihilations. Very weak γ-ray excesses ( > 2 σ) are found in some dSphs. The most significant signal for dark matter annihilation is observed toward Willman 1, the peak TS value is ∼ 9.6 at a dark matter mass ∼ 60 GeV for the annihilation channel . Due to the low significance of the signal, its true origin cannot be determined at the moment. The observed γ-ray excess in the vicinity of Reticulum II shows variation, indicating that the signal is unlikely to be attributable to dark matter annihilation. Furthermore, the γ-ray excesses in Eridanus II and Reticulum III are significantly offset from their centers, possibly due to contamination from astrophysical sources. Three other targets (Boötes II, Ursa Minor and Crater II) show local significance between 2 - 2.5σ, whereas the corresponding cross-sections are inconsistent with the stringent limits from the stacked analysis of dSphs, ruling out a dark matter annihilation origin.
{"title":"Search for γ-ray emission from dwarf spheroidal galaxies with Fermi-LAT data","authors":"Shang Li","doi":"10.1016/j.jheap.2025.100536","DOIUrl":"10.1016/j.jheap.2025.100536","url":null,"abstract":"<div><div>This study uses approximately 17 years of <em>Fermi</em>-LAT data to search for <em>γ</em>-ray emission from 45 Milky Way dwarf spheroidal galaxies (dSphs, including candidates). No significant ( > 5<em>σ</em>) <em>γ</em>-ray signal is found in the scenarios of dark matter annihilations. Very weak <em>γ</em>-ray excesses ( > 2 <em>σ</em>) are found in some dSphs. The most significant signal for dark matter annihilation is observed toward Willman 1, the peak TS value is ∼ 9.6 at a dark matter mass ∼ 60 GeV for the annihilation channel <span><math><mrow><mi>χ</mi><mi>χ</mi><mo>→</mo><msup><mi>τ</mi><mo>+</mo></msup><msup><mi>τ</mi><mo>−</mo></msup></mrow></math></span>. Due to the low significance of the signal, its true origin cannot be determined at the moment. The observed <em>γ</em>-ray excess in the vicinity of Reticulum II shows variation, indicating that the signal is unlikely to be attributable to dark matter annihilation. Furthermore, the <em>γ</em>-ray excesses in Eridanus II and Reticulum III are significantly offset from their centers, possibly due to contamination from astrophysical sources. Three other targets (Boötes II, Ursa Minor and Crater II) show local significance between 2 - 2.5<em>σ</em>, whereas the corresponding cross-sections are inconsistent with the stringent limits from the stacked analysis of dSphs, ruling out a dark matter annihilation origin.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100536"},"PeriodicalIF":10.5,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976521","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 : 2025-12-27DOI: 10.1016/j.jheap.2025.100544
Ribhu Pal , Arnab Roy
In this article, we report the numerical results of two-dimensional axis-symmetric relativistic jet issuing from AGN, performed using a high-order finite-volume scheme within the PLUTO code, focusing on favorable conditions for star formation within jet-inflated cocoons. A localized square subdomain of the cocoon was statistically analyzed for velocity divergence (∇ · v), current density (J), density fluctuations (), and log-normalized density () under varying jet magnetizations (σϕ, σz). Enhanced toroidal magnetization (σϕ) was found to amplify magnetic hoop stresses, producing compact, filamentary overdense clumps and strongly non-Gaussian current density and density fluctuation PDFs with pronounced skewness and kurtosis. Concurrently, the variance of the log-normal density decreased with increasing σϕ, indicating reduced large-scale density contrast despite intense local overdensities. Moderate toroidal magnetization (σϕ ∼ 0.5) yielded both numerous overdense clumps and high global density variance, providing the most favorable conditions for star formation. These results establish a direct link between jet magnetization, cocoon compression, and pre-favorable conditions for star-forming potential inside jet-induced cocoon ISM during active phase of AGN-jet. While onset of star formation is expected to occur during episodic jet-off phases, can be the future scope of current research work.
{"title":"Magnetized relativistic jet-induced cocoon as a cradle of star formation","authors":"Ribhu Pal , Arnab Roy","doi":"10.1016/j.jheap.2025.100544","DOIUrl":"10.1016/j.jheap.2025.100544","url":null,"abstract":"<div><div>In this article, we report the numerical results of two-dimensional axis-symmetric relativistic jet issuing from AGN, performed using a high-order finite-volume scheme within the PLUTO code, focusing on favorable conditions for star formation within jet-inflated cocoons. A localized square subdomain of the cocoon was statistically analyzed for velocity divergence (∇ · <strong>v</strong>), current density (J), density fluctuations (<span><math><mrow><msup><mi>ρ</mi><mo>′</mo></msup><mo>=</mo><mi>ρ</mi><mo>−</mo><mrow><mo>〈</mo><mi>ρ</mi><mo>〉</mo></mrow></mrow></math></span>), and log-normalized density (<span><math><mrow><mi>s</mi><mo>=</mo><mi>ln</mi><mo>(</mo><mi>ρ</mi><mo>/</mo><mo>〈</mo><mi>ρ</mi><mo>〉</mo><mo>)</mo></mrow></math></span>) under varying jet magnetizations (<em>σ<sub>ϕ</sub>, σ<sub>z</sub></em>). Enhanced toroidal magnetization (<em>σ<sub>ϕ</sub></em>) was found to amplify magnetic hoop stresses, producing compact, filamentary overdense clumps and strongly non-Gaussian current density and density fluctuation PDFs with pronounced skewness and kurtosis. Concurrently, the variance of the log-normal density decreased with increasing <em>σ<sub>ϕ</sub></em>, indicating reduced large-scale density contrast despite intense local overdensities. Moderate toroidal magnetization (<em>σ<sub>ϕ</sub></em> ∼ 0.5) yielded both numerous overdense clumps and high global density variance, providing the most favorable conditions for star formation. These results establish a direct link between jet magnetization, cocoon compression, and pre-favorable conditions for star-forming potential inside jet-induced cocoon ISM during active phase of AGN-jet. While onset of star formation is expected to occur during episodic jet-off phases, can be the future scope of current research work.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100544"},"PeriodicalIF":10.5,"publicationDate":"2025-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938337","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 : 2025-12-26DOI: 10.1016/j.jheap.2025.100542
Mozhdeh Bitaj, Kourosh Nozari
We study the reheating process in a non-minimal Tachyon inflation with three potentials: exponential potential , inverse power law potential and inverse Cosh potential . We constrain these models in confrontation with Planck2018 TT, TE, EE+lowE+lensing+BK14(18)+BAO+DESI2024+Union3 joint data and also the latest results from the Atacama Cosmology Telescope (ACT) dataset. In this comparison, we identify an appropriate observational range for the non-minimal coupling parameter ξ for the exponential potential parameter α ∈ [0.1, 1], inverse power law, and inverse Cosh potentials. A successful reheating stage with acceptable reheating number of e-folds, Nre, and reheating temperature, Tre, happens in the exponential potential model for α ∈ [0.2, 0.6] as well as the two models mentioned above, all with the equation of state parameter .
{"title":"Reheating in a non-minimal tachyon cosmic inflation","authors":"Mozhdeh Bitaj, Kourosh Nozari","doi":"10.1016/j.jheap.2025.100542","DOIUrl":"10.1016/j.jheap.2025.100542","url":null,"abstract":"<div><div>We study the reheating process in a non-minimal Tachyon inflation with three potentials: exponential potential <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow><mo>=</mo><msup><mi>M</mi><mn>4</mn></msup><mi>exp</mi><mrow><mo>(</mo><mo>−</mo><mfrac><mi>α</mi><msub><mi>M</mi><mrow><mi>p</mi><mi>l</mi></mrow></msub></mfrac><mi>ϕ</mi><mo>)</mo></mrow></mrow></math></span>, inverse power law potential <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow><mo>=</mo><mstyle><mfrac><mi>λ</mi><mrow><mn>1</mn><mo>+</mo><msup><mi>ϕ</mi><mn>4</mn></msup></mrow></mfrac></mstyle></mrow></math></span> and inverse Cosh potential <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow><mo>=</mo><mstyle><mfrac><mi>λ</mi><mrow><mi>cosh</mi><mi>ϕ</mi></mrow></mfrac></mstyle></mrow></math></span>. We constrain these models in confrontation with Planck2018 TT, TE, EE+lowE+lensing+BK14(18)+BAO+DESI2024+Union3 joint data and also the latest results from the Atacama Cosmology Telescope (ACT) dataset. In this comparison, we identify an appropriate observational range for the non-minimal coupling parameter <em>ξ</em> for the exponential potential parameter <em>α</em> ∈ [0.1, 1], inverse power law, and inverse Cosh potentials. A successful reheating stage with acceptable reheating number of e-folds, <em>N<sub>re</sub></em>, and reheating temperature, <em>T<sub>re</sub></em>, happens in the exponential potential model for <em>α</em> ∈ [0.2, 0.6] as well as the two models mentioned above, all with the equation of state parameter <span><math><mrow><mi>ω</mi><mo>=</mo><mn>1</mn></mrow></math></span>.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"51 ","pages":"Article 100542"},"PeriodicalIF":10.5,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884290","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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