Journal of High Energy Astrophysics最新文献

{"title":"Observational viability of fractional holographic dark energy in LRS Bianchi type-I cosmological model","authors":"Shivangi Rathore,&nbsp;Elangbam Chingkheinganba Meetei,&nbsp;S. Surendra Singh","doi":"10.1016/j.jheap.2025.100502","DOIUrl":"10.1016/j.jheap.2025.100502","url":null,"abstract":"<div><div>In this work, we scrutinized the Locally Rotational Symmetry (LRS) Bianchi type-I cosmological model in the presence of fractional holographic dark energy. Holographic dark energy theories present a fascinating interface to probe late-time cosmology, guided by contemporary quantum gravity ideas. This model extends the conventional holographic dark energy framework by incorporating features from fractional calculus recently applied, e.g., in cosmological settings. In this manner, we retrieve a novel form of holographic dark energy density. We calculate the value of the Hubble parameter <span><math><mi>H</mi><mo>(</mo><mi>z</mi><mo>)</mo></math></span> using the field equations. After that, we fit the model by employing the MCMC techniques to observational data, which includes Hubble, Hubble+BAO, Hubble+Pantheon+SH0ES, and Hubble+BAO+Pantheon+SH0ES datasets. With the help of these datasets, we calculate the model parameters, viz. <span><math><mi>H</mi><mo>(</mo><mi>z</mi><mo>)</mo><mo>,</mo><mi>α</mi></math></span>, and <span><math><msub><mrow><mi>Ω</mi></mrow><mrow><msub><mrow><mi>m</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></msub></math></span>. Our results indicate that the evolution of the density parameters corresponding to dark energy (DE) and dark matter (DM), particularly for <span><math><mi>α</mi><mo>=</mo><mn>1.01</mn></math></span>, along with the transition of the deceleration parameter <em>q</em> from positive values to −1, reflects a phase of accelerated expansion that closely resembles the ΛCDM model. The behavior of the equation of state (EoS) parameter further demonstrates that the Universe's evolution aligns well with the framework of the fractional holographic dark energy (FHDE) model, suggesting its compatibility with scenarios of late-time cosmology. Moreover, the analysis of the statefinder diagnostics (<span><math><mi>r</mi><mo>,</mo><mi>s</mi></math></span>) and the corresponding (<span><math><mi>r</mi><mo>,</mo><mi>s</mi></math></span>) trajectories reveal characteristics that converge towards the ΛCDM fixed point. A comparison between the observational constraints on our model parameters and those of the ΛCDM model exhibits a strong degree of agreement, thereby reinforcing the physical plausibility and consistency of the proposed cosmological model.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100502"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the role of mass accretion rates during the outburst evolution of MAXI J1535-571","authors":"Ambrose C. EZE ,&nbsp;Romanus N.C. EZE","doi":"10.1016/j.jheap.2025.100497","DOIUrl":"10.1016/j.jheap.2025.100497","url":null,"abstract":"<div><div>MAXI J1535-571 outburst evolution is driven by physical mechanisms that mediate the accretion flow dynamical behavior/characteristics. In this study, MAXI J1535-571 data were analyzed. Spectral <strong>fitting and modelling</strong> were performed using phenomenological and physical models. MAXI J1535-571 X-ray spectra with an acceptable statistical fit were obtained. Accretion flow characteristics and their correlations were determined. The components of the accretion flow/rates show variations/fluctuations at different epochs. This indicates the dynamical behavior. The accretion flow geometry is “sombrero” or patchy-flaring turbulence flow. The decrease in accretion rate ratio (ARR) and shock location (Xs) shows that the outburst evolution progresses on timescales. A compression ratio (R) of 3.7 – 4.0 shows that the oscillating shock in the accretion flow is strong. The resonance condition of (0.62 – 0.79) ± 0.04 indicates that the timescales of components of the accretion flow roughly matched. A Quasi-Periodic Oscillation frequency (vQPO) of 0.560 Hz – 2.239 Hz is consistent with the type-C signature. Moreover, the components of the accretion flow/rate variations/fluctuations caused a uniform distribution of energy spectral indices and variations/fluctuations in the power-law photon index. The variations/fluctuations in mass accretion rate create the same physical features observed in other accretion flow parameters. Hence, mass accretion rate variations/fluctuations cause the decrease in the ARR, shock location, and perhaps, delay in the transition period and spectral evolution of MAXI J1535-571 as the outburst progresses.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100497"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectral energy distribution analysis of the supersoft X-ray source CAL 87: Multiwavelength constraints","authors":"Paulo E. Stecchini ,&nbsp;Francisco Jablonski ,&nbsp;Marcos P. Diaz ,&nbsp;Alexandre S. Oliveira ,&nbsp;Flavio D'Amico ,&nbsp;Natália Palivanas","doi":"10.1016/j.jheap.2025.100467","DOIUrl":"10.1016/j.jheap.2025.100467","url":null,"abstract":"<div><div>We analyse the spectral energy distribution (SED) of the eclipsing supersoft X-ray source CAL<!--> <!-->87 covering wavelengths from X-rays to the near-infrared. Our study incorporates 26 data points across ultraviolet to near-infrared, sourced from published literature, unpublished data, and new observations. In addition, archival <em>XMM-Newton</em> spectra were used to represent the X-ray emission. Care was taken to use out-of-eclipse flux measurements when the irradiated side of the companion faces the observer. The SED model includes contributions from a central source, a reprocessed accretion disk, and an irradiated companion star atmosphere, resulting in a good match to the observed fluxes. The revised and new parameters for the disk and the central source align with previous studies and match expectations for such systems. The temperature of the irradiated side of the companion star was estimated based on its <span><math><mi>B</mi><mo>−</mo><mi>V</mi></math></span> colour during the secondary eclipse. This work highlights the importance of broad wavelength coverage for understanding the properties of supersoft X-ray sources.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100467"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145099037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Can future CMB data discriminate between a cosmological constant and dynamical dark energy?","authors":"Anna Chiara Ferri,&nbsp;Alessandro Melchiorri","doi":"10.1016/j.jheap.2025.100504","DOIUrl":"10.1016/j.jheap.2025.100504","url":null,"abstract":"<div><div>Recent cosmological analyses combining <em>Planck</em> CMB data with baryon acoustic oscillation (BAO) measurements from the DESI collaboration have revealed a statistically significant preference for evolving dark energy (DE) models over the standard cosmological constant. In particular, fits using the Chevallier–Polarski–Linder (CPL) parameterization indicate a <span><math><mo>∼</mo><mn>4</mn><mi>σ</mi></math></span> deviation from a constant equation of state, suggesting a possible departure from the ΛCDM paradigm. In this work, we investigate whether forthcoming cosmic microwave background (CMB) experiments such as CMB-S4 and Simons Observatory (SO) can independently discriminate between ΛCDM and these dynamical dark energy scenarios without relying on external low-redshift data. We perform a detailed Fisher matrix forecast and mock likelihood analysis using fiducial cosmologies consistent with current DESI+Planck-preferred CPL models. Our results show that, under realistic experimental assumptions, next-generation CMB data can place meaningful constraints on DE evolution parameters <span><math><msub><mrow><mi>w</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>w</mi></mrow><mrow><mi>a</mi></mrow></msub></math></span>, and potentially detect departures from a cosmological constant at the ∼2–3<em>σ</em> level. We discuss the implications for model selection and the robustness of CMB-based probes in testing extensions to the standard cosmological model.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100504"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection of new very-high-energy sources outside the galactic plane in the Fermi-LAT data","authors":"M.S. Pshirkov ,&nbsp;A.S. Kovankin","doi":"10.1016/j.jheap.2025.100492","DOIUrl":"10.1016/j.jheap.2025.100492","url":null,"abstract":"<div><div>We present a search for spatio-temporal clusters in 16 years of Fermi-LAT very-high-energy (VHE; <span><math><mi>E</mi><mo>&gt;</mo><mn>100</mn></math></span> GeV) data using the DBSCAN algorithm, focusing on high Galactic latitude (<span><math><mo>|</mo><mi>b</mi><mo>|</mo><mo>&gt;</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>∘</mo></mrow></msup></math></span>) clusters with ≥5 events and transient doublets (two events within ≤3 days). Of 107 detected clusters, two correspond to previously unidentified VHE sources: weak BL Lacertae objects 4FGL J0039.1-2219 and 4FGL J0212.2-0219, promising targets for next-generation VHE observatories.</div><div>Due to the low VHE photon background, even doublets with a duration of several days exhibited high statistical significance. While most of the 114 detected doublets originated from bright TeV emitters (e.g., Mrk 421, Mrk 501), we identified six VHE flares lacking TeVCat associations. Five of these flares correlate with sources from the Third Catalog of Fermi-LAT High-Energy Sources (3FHL), while one 'orphan' flare lacks a high-energy (HE; <span><math><mi>E</mi><mo>&gt;</mo><mn>10</mn></math></span> GeV) source counterpart. Some of these flares reached extreme luminosities of <span><math><mi>O</mi><mo>(</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>47</mn></mrow></msup><mspace></mspace><mrow><mi>erg</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><mo>)</mo></math></span>.</div><div>No consistent temporal correlation emerged between HE and VHE activity: HE flares preceded, coincided with, or followed VHE emission across sources, with some showing no HE counterpart. Remarkably, 3FHL J0308.4+0408 (NGC 1218) is a Seyfert Type I galaxy, while no object of this class was known as a VHE emitter before. The ‘orphan’ flare without any known HE source in the vicinity may originate from NGC 5549, a low-luminosity LINER galaxy. Both sources expand the limited sample of non-blazar AGN detected at VHE energies. The fact that some weak sources with non-aligned jets and, sometimes, even without any traces of HE activity, could demonstrate very short and powerful VHE flares cannot be easily accounted in many current AGN models and calls for their further development.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100492"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraints on spatial curvature and dark energy dynamics in the wCDM model from DESI DR1 and DR2","authors":"Manish Yadav ,&nbsp;Archana Dixit ,&nbsp;M.S. Barak ,&nbsp;Anirudh Pradhan","doi":"10.1016/j.jheap.2025.100514","DOIUrl":"10.1016/j.jheap.2025.100514","url":null,"abstract":"<div><div>In this study, we investigate the <em>w</em>CDM dynamical dark energy model with spatial curvature utilizing the recently released DESI Collaboration data (DR1 and DR2) in conjunction with other observational probes such as BBN, Observational Hubble Data (OHD), and Pantheon Plus (PP). Our investigation attempts to discover which DESI dataset gives a better match to the <em>w</em>CDM framework and assess the impact of spatial curvature on cosmological constraints. We find that the cosmic curvature parameter, <span><math><msub><mrow><mi>Ω</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span>, disfavors the cosmological constant for the DR2+BBN and DR2+BBN+OHD data combinations. However, the deviation from the cosmological constant remains below the 1<em>σ</em> level, indicating a mild preference for a open universe. In contrast, when using the DR1 based combinations namely DR1+BBN and DR1+BBN+OHD—the deviation from the cosmological constant increases to approximately 1.2<em>σ</em>, suggesting a slightly stronger indication of a open geometry. Also, the best-fit values of the Hubble constant (<span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>) obtained from the DR1+BBN+OHD+PP and DR2+BBN+OHD+PP combinations within the dynamical dark energy model are consistent with the results reported by the Planck Collaboration. Our findings provide constraints on the dark energy EoS parameter <span><math><msub><mrow><mi>w</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, reveal a mild but notable deviation from the vacuum energy (<span><math><mi>w</mi><mo>=</mo><mo>−</mo><mn>1</mn></math></span>) scenario at a significance level 1.8<em>σ</em> from DR2+BBN+OHD+PP and 0.5<em>σ</em> from DR1+BBN+OHD+PP, both favoring the quintessence region of dark energy. Furthermore, the key physical distance measures <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>H</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>V</mi></mrow></msub></math></span>, and <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>M</mi></mrow></msub></math></span> show better consistency with our model when analyzed with the DR2 data.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100514"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clues on the X-ray emission mechanism of blazars PKS 2155−304 and 3C 454.3 through polarization studies","authors":"Athira M. Bharathan ,&nbsp;C.S. Stalin ,&nbsp;Sunder Sahayanathan ,&nbsp;Blesson Mathew","doi":"10.1016/j.jheap.2025.100472","DOIUrl":"10.1016/j.jheap.2025.100472","url":null,"abstract":"<div><div>X-ray polarization measurable with the imaging X-ray Polarimetry Explorer (<em>IXPE</em>) could constrain the long debated leptonic versus hadronic origin for the high energy component in the broad band spectral energy distribution (SED) of blazars. We report here the results from <em>IXPE</em> and SED modeling of PKS 2155−304 and 3C 454.3, a high and low synchrotron peaked blazar. For PKS 2155−304, from model-independent analysis, we found polarization angle <span><math><msub><mrow><mi>Ψ</mi></mrow><mrow><mi>X</mi></mrow></msub></math></span> = (130 ± 2.5) deg and polarization degree <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mi>X</mi></mrow></msub></math></span> = (20.9 ± 1.8)% in the 2−8 keV band in agreement with spectro-polarimetric analysis. We found <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mi>X</mi></mrow></msub></math></span> to vary with time and indications of it to vary between energies, suggesting that the emission regions are stratified. For 3C 454.3, we did not detect X-ray polarization in the June 2023 observation, analyzed here for the first time. The detection of X-ray polarization in PKS 2155−304 and its non-detection in 3C 454.3 is in accordance with the X-ray emission from synchrotron and inverse Compton process, respectively, operating in these sources. Further, our division of the dataset into finer time bins allows a more granular view of polarization variability. Additionally, we modeled the broadband SEDs of both the sources using data acquired quasi-simultaneously with <em>IXPE</em>, in the optical, UV and X-rays from <em>Swift</em>, <em>AstroSat</em> and <em>γ</em>-rays from <em>Fermi</em>. In PKS 2155−304, the observed X-ray is found to lie in the high energy tail of the synchrotron component of the SED, while in 3C 454.3 the observed X-ray lies in the rising part of the inverse Compton component of the SED. Our SED modeling along with X-ray polarization observations favor a leptonic scenario for the observed X-ray emission in PKS 2155−304. The SED modeling for these specific <em>IXPE</em> epochs has not been presented before, allowing us to place additional constraints on the physical conditions in the jet. These results strengthen the case for a structured jet model where X-ray emission originates from a compact acceleration zone near the shock front, while lower-energy optical emission is produced in a broader, more turbulent region.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100472"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145222607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Search for GeV emission from luminous infrared galaxies with 16 years of Fermi-LAT data","authors":"Shang Li","doi":"10.1016/j.jheap.2025.100499","DOIUrl":"10.1016/j.jheap.2025.100499","url":null,"abstract":"<div><div>A systematic search for <em>γ</em>-ray emission from luminous infrared galaxies is conducted using 16 years of <em>Fermi</em>-LAT data in the energy range from 300 MeV to 500 GeV. Five galaxies are first identified with a test statistic (TS) greater than 16.0. A significant <em>γ</em>-ray signal, spatially coincident with IRAS 17578-0400, has been detected with a significance of ∼ 6.3<em>σ</em>. The <em>γ</em>-ray flux exhibits significant variability over the observation period. Moreover, the <em>γ</em>-ray luminosity exceeds the value predicted by the correlation between <em>γ</em>-ray luminosity and total infrared luminosity. The <em>γ</em>-ray emission may originate from an active galactic nucleus in IRAS 17578-0400. Gamma-ray emissions have been detected from two galaxies (NGC 2369 and IC 4280) with a significance greater than 5<em>σ</em>. However, since there are other potential <em>γ</em>-ray emitters spatially coincident with the two sources, the possibility that these signals are caused by other sources cannot be ruled out. Two other galaxies, IRAS 21101+5810 and MCG+08-11-002, show evidence of <em>γ</em>-ray emission, making them promising targets for future studies.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100499"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparative Bayesian PINN–MCMC analysis of Barrow–Tsallis holographic dark energy with neutrinos: Toward resolving the Hubble tension","authors":"Muhammad Yarahmadi,&nbsp;Amin Salehi","doi":"10.1016/j.jheap.2025.100498","DOIUrl":"10.1016/j.jheap.2025.100498","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We present a comprehensive analysis of the Barrow–Tsallis Holographic Dark Energy (BTHDE) model within a spatially flat FLRW cosmology, focusing on a comparative assessment between traditional Markov Chain Monte Carlo (MCMC) methods and a Bayesian Physics-Informed Neural Network (PINN). By embedding the modified Friedmann dynamics directly into the learning architecture, the Bayesian PINN framework enforces physical consistency while enabling efficient posterior sampling. We employ a broad suite of cosmological observations, including Planck 2018 CMB temperature and polarization data, CMB lensing, Baryon Acoustic Oscillations (BAO), Cosmic Chronometers (CC), and the Pantheon+ Type Ia supernovae compilation, to jointly constrain the Hubble constant &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the Tsallis nonextensive parameter &lt;em&gt;q&lt;/em&gt;, Barrow exponent Δ, Granda–Oliveros cutoff parameters &lt;em&gt;α&lt;/em&gt; and &lt;em&gt;β&lt;/em&gt;, and the total neutrino mass &lt;span&gt;&lt;math&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ν&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;. In the late-time (CC + Pantheon+) analyses, we adopt flat, physically motivated priors on the baryon and cold dark matter densities (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Ω&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Ω&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;) solely for the internal calibration of the sound horizon &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, without employing any Planck-based or early-universe likelihoods. The Bayesian PINN consistently yields sharper posterior distributions than MCMC, particularly for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ν&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, while ensuring solution smoothness and dynamical compatibility. Both methods place the inferred &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; values between the Planck and SH&lt;sub&gt;0&lt;/sub&gt;ES estimates, lowering the Hubble tension to the 1.3&lt;em&gt;σ&lt;/em&gt;–2.1&lt;em&gt;σ&lt;/em&gt; range. In the MCMC framework, combined CMB and low-redshift datasets constrain &lt;span&gt;&lt;math&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ν&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0.114&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mtext&gt;eV&lt;/mtext&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;70.6&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;1.35&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mtext&gt;km/s/Mpc&lt;/mtext&gt;&lt;/math&gt;&lt;/span&gt;. Our results demonstrate the viability of the BTHDE model as a compelling alternative to ΛCDM and highlight the complementary strengths of Bayesian PINNs and MCMC in probing extended dark energy scenarios governed by generalized entropy frameworks.&lt;/div&gt;&lt;","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"50 ","pages":"Article 100498"},"PeriodicalIF":10.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultra-high energy cosmic rays with UFA-15 source model in Bumblebee gravity theory","authors":"Swaraj Pratim Sarmah,&nbsp;Pranjal Sarmah,&nbsp;Umananda Dev Goswami","doi":"10.1016/j.jheap.2025.100451","DOIUrl":"10.1016/j.jheap.2025.100451","url":null,"abstract":"<div><div>We explore the effects of Bumblebee gravity on the propagation of ultra-high energy cosmic rays (UHECRs) using astrophysical sources modeled in the Unger-Farrar-Anchordoqui (UFA) framework (2015), which includes star formation rate (SFR), gamma-ray bursts (GRBs), and active galactic nuclei (AGN). We compute the density enhancement factor for various source separations distances (<span><math><msub><mrow><mi>d</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span>s) up to 100 Mpc within the Bumblebee gravity scenario. Additionally, we calculate the CRs flux and their suppression, goodness-of-fit values obtained from comparisons with observational data from the Pierre Auger Observatory (PAO) and the Telescope Array experiment data for the flux and the Levenberg-Marquardt algorithm for suppression. The anisotropy in the CRs arrival directions is examined, with corresponding goodness-of-fit values obtained from the PAO surface detector data (SD 750 and SD 1500). Finally, we present skymaps of flux and anisotropy under different model assumptions, providing insights into the observational signatures of UHECRs in Bumblebee gravity. We show that Bumblebee gravity stands as a viable cosmological model for explaining key observational features of UHECRs, including spectrum, composition and anisotropy. Our results show that increasing the Bumblebee gravity parameter <em>l</em> enhances the density factor <em>ξ</em>, particularly at low energies, highlighting Lorentz violation's impact on CRs' propagation. Larger <span><math><msub><mrow><mi>d</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span> values amplify deviations from the ΛCDM model, with AGN sources dominating at high energies and GRB/SFR sources at lower energies. The skymaps indicate the structured flux patterns at large <span><math><msub><mrow><mi>d</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span> and structured anisotropies at higher energies.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100451"},"PeriodicalIF":10.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896752","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}