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Investigating stable quark stars in Rastall-Rainbow gravity and their compatibility with gravitational wave observations J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-02-28 Takol Tangphati, Dhruba Jyoti Gogoi, Anirudh Pradhan, Ayan Banerjee
We present a stable model for quark stars in Rastall-Rainbow (R-R) gravity. The structure of this configuration is obtained by utilizing an interacting quark matter equation of state. The R-R gravity theory is developed as a combination of two distinct theories, namely, the Rastall theory and the gravity's rainbow formalism. Depending on the model parameters (), the mass-radius relations are numerically
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Type-I X-ray burst evolution of the new millisecond pulsar MAXI J1816–195 revealed by Insight-HXMT J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-02-28 P.J. Wang, Y.P. Chen, L. Ji, S. Zhang, S.N. Zhang, L.D. Kong, L. Zhang, L. Tao, J.L. Qu, M.Y. Ge, J. Li, Z. Chang, J.Q. Peng, Q.C. Shui, Z.S. Li
We report a study of the type-I X-ray bursts and persistent spectrum of the 2022 outburst of the newly discovered accreting millisecond pulsar MAXI J1816–195 observed by . The spectra of MAXI J1816–195 are similar to other accreting millisecond pulsars, i.e., a Comptonization shape with an electron temperature of ∼10 keV. We find that the profiles of type-I X-ray bursts, as well as their spectra, evolve
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Soft X-ray observing the cosmic sources by the ESA–CAS satellite SMILE J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-02-22 Vojtěch Šimon, René Hudec, Andrew Read
This paper describes the scientific potential of a Soft X-ray Imager (SXI) onboard the ESA–CAS satellite for investigating cosmic X-ray sources of various types. We show that this instrument, albeit designed for X-ray imaging of solar wind Charge eXchange of the magnetosheath and the cusps, is also essential for astrophysics because it is able to provide wide-field imaging of the sky in the soft X-ray
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Generalized wormhole models within galactic halo region in torsion and matter coupling gravity formalism J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-02-22 G. Mustafa, Abdelghani Errehymy, Faisal Javed, S.K. Maurya, Sudan Hansraj, Sobia Sadiq
In the current analysis, we investigate the possible existence of generalized Wormhole models within the galactic halo region by analyzing specific dark matter models. The observational data is checked in the framework of torsion within minimal matter coupling gravity. By using the variational approach modified versions of the field equations under the anisotropic source of matter are calculated. To
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Different behaviors of wavelet results for type-B and type-C QPOs of MAXI J1535-571 based on NICER data J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-02-21 Xiao Chen, Wei Wang
Wavelet analysis, in addition to power density spectra, is another method to study the quasi-periodic signals in the light curves, but has been rarely used in black hole X-ray transients. We performed wavelet analysis of X-ray timing features and quasi-periodic oscillations (QPOs) based on NICER observations of the black hole candidate MAXI J1535-571 in this paper. Separating the light curves by the
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Reduction of ultra-high energy neutrino flux for spacelike neutrinos from extragalactic sources J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-02-13 J. Rembieliński, J. Ciborowski
Assuming that neutrinos are spacelike (tachyonic) fermions, we calculate width for the kinematically allowed, lepton number conserving, three-body decay in the Standard Model. Decays of tachyonic neutrinos over cosmological distances can lead to a reduction of the neutrino flux in the high-energy end of the spectrum. We estimate upper limits on the spacelike neutrino mass based on the PeV-energy cosmological
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The challenge of identifying INTEGRAL sources on the Galactic plane J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-01-22 Raffaella Landi, Loredana Bassani, Gabriele Bruni, Manuela Molina, Nicola Masetti, Angela Malizia, Mariateresa Fiocchi, Angela Bazzano, Pietro Ubertini
The International Gamma-ray Astrophysics Laboratory () has been surveying the sky above 20 keV since its launch in 2002 providing new insights into the nature of the sources that populate our Universe at soft -ray energies. The latest IBIS/ISGRI survey lists 929 hard X-ray sources, of which 113 are reported as unidentified, i.e. lacking a lower energy counterpart or simply not studied in other wavebands
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Exact scalar quasibound states solutions of f(R) theory's static spherically symmetric black hole J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-01-15 David Senjaya
Following the recent developments in black holes' quasibound states exact solutions by , in this letter, we present a novel exact solution of quasibound states of a scalar around a static spherically symmetric black hole solution of theory of gravity. We start with the relativistic scalar field wave equation, i.e. the Klein-Gordon equation, isolating the radial equation and finally successfully obtain
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Particle correlation in the cosmic ray showers around the spectral knee J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-01-11 Tadeusz Wibig
In this paper, we answer the question to what extent the particles in showers initiated by particles with energies of 10 – 10 eV observed at the edges of extensive air showers, where average particle densities are low (< a few per m), are correlated. The particle number multiplicity distributions in the surface detectors of the shower arrays are affected by the existence of such a correlation. They
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On the statistical assumption on the distance moduli of Supernovae Ia and its impact on the determination of cosmological parameters J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-01-04 M.G. Dainotti, G. Bargiacchi, M. Bogdan, S. Capozziello, S. Nagataki
Type Ia Supernovae (SNe Ia) are considered the most reliable and they have played an invaluable role in cosmology since the discovery of the Universe's accelerated expansion. During the last decades, the SNe Ia samples have been improved in number, redshift coverage, calibration methodology, and systematics treatment. These efforts led to the most recent (2018) and (2022) releases, which enable to
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The BOAT GRB 221009A: A Poynting-flux-dominated narrow jet surrounded by a matter-dominated structured jet wing J. High Energy Astrophys. (IF 3.8) Pub Date : 2024-01-04 Bing Zhang, Xiang-Yu Wang, Jian-He Zheng
We argue that the broad-band observations of the brightest-of-all-time (BOAT) GRB 221009A reveal a physical picture involving two jet components: a narrow (∼0.6 degree half opening angle) pencil-beam jet that has a Poynting-flux-dominated jet composition, and a broader matter-dominated jet with an angular structure. We discuss various observational evidence that supports such a picture. To treat the
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Constraints on the internal physics of neutron stars from the observational data of several young pulsars: The role of a power-law decaying dipole magnetic field J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-12-20 Yu-Long Yan, Quan Cheng, Xiao-Ping Zheng
The observational data (e.g., the timing data and magnetic tilt angles ) of young pulsars can be used to probe some critical issues about the internal physics of neutron stars (NSs), for instance, the number of precession cycles and the internal magnetic field configuration (IMFC) of NSs. Evolution of the dipole magnetic field of NSs may play an important role in determining the final results. In this
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Studying the variations of the cyclotron line in Cen X-3 using Insight-HXMT J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-12-20 Qi Liu, Wei Wang, Wen Yang, Xiao Chen, Hanji Wu
We investigate the cyclotron resonant scattering features (CRSFs) of the accreting X-ray pulsar Cen X-3 and significantly detect the 29 keV cyclotron line features in the hard X-ray averaged spectroscopy studies based on the recent Insight-HXMT observations in 2022, when Cen X-3 has X-ray luminosity erg s in the bands of 2 – 60 keV. We do not find a harmonic line in the average spectra based on different
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GRB 080710: A narrow, structured jet showing a late, achromatic peak in the optical and infrared afterglow? J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-12-12 Kaori Obayashi, Ayumu Toriyama, Mayu Murakoshi, Yuri Sato, Shuta J. Tanaka, Takanori Sakamoto, Ryo Yamazaki
We present a possible theoretical interpretation of the observed afterglow emission of long gamma-ray burst GRB 080710. While its prompt GRB emission properties are normal, the afterglow light curves in the optical and infrared bands are exceptional in two respects. One is that the observed light curves of different wavelengths have maximum at the same time, and that the achromatic peak time, s after
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Corrigendum to “Energetic requirements of the gamma-ray emission from pulsars: A nonparametric analysis of the data in the Fermi-LAT 12-Year Catalog” [J. High Energy Astrophys. 37 (2023) 62–70] J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-11-21 Houshang Ardavan
Abstract not available
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Anisotropic quark stars in energy-momentum squared gravity J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-11-14 Takol Tangphati, Abdelghani Errehymy, Ayan Banerjee, Anirudh Pradhan
At super-saturation densities, quarks in the core of neutron stars (NSs) have been a subject of intense investigation for last few decades. In particular, an intriguing conjecture has emerged suggesting that the true ground state of hadronic matter may be strange quark matter (SQM). In the present manuscript, we study internal structure and the physical properties of quark stars (QSs) in energy-momentum
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Insight-HXMT observations on thermonuclear X-ray bursts from 4U 1608–52 in 2022: The accretion rate dependent anisotropy of burst emission J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-11-14 Yu-Peng Chen, Shu Zhang, Long Ji, Shuang-Nan Zhang, Peng-Ju Wang, Ling-Da Kong, Zhi Chang, Jing-Qiang Peng, Qing-Cang Shui, Jian Li, Lian Tao, Ming-Yu Ge, Jin-Lu Qu
Thermonuclear X-ray bursts occur on the surface of an accreting neutron star (NS), and their characteristics and interplay with the surrounding circumstance could be a clue to understand the nature of the NS and accretion process. For this purpose, Insight-HXMT has performed high cadence observations on the bright thermonuclear X-ray burster–4U 1608–52 during its outburst in July and August 2022; nine
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Exact analytical quasibound states of a scalar particle around a slowly rotating black hole J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-10-23 David Senjaya
In this work, behaviour of massive and massless scalar particle around a slowly rotating black hole in 3+1 dimension is investigated. Exact solutions of the Klein-Gordon equation, i.e. the wave functions and energy levels are discovered. The quasibound state has complex-valued energy levels E=ER+iEI where the real part ER is directly related to the particle's energy while the imaginary part represents
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The unprecedented flaring activities around Mrk 421 in 2012 and 2013: The test for neutrino and UHECR event connection J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-10-26 Nissim Fraija, Edilberto Aguilar-Ruiz, Antonio Galván, Jose Antonio de Diego Onsurbe, Maria G. Dainotti
Since its mission, Fermi Collaboration reported the highest flux observed during July - September 2012 for the BL Lac Markarian 421 (Mrk 421). The integrated flux was eight times greater than the average flux reported in the second Fermi catalog. During April 2013, Mrk 421 exhibited the highest TeV γ-ray and optical fluxes recorded. The Telescope Array (TA) collaboration reported the arrival of 72
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Bayesian evidence for spectral lag transition due to Lorentz invariance violation for 32 Fermi/GBM Gamma-ray bursts J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-10-16 Vibhavasu Pasumarti, Shantanu Desai
We use the spectral lag data of 32 long GRBs detected by Fermi/GBM, which has been recently collated in Liu et al. (2022) to quantify the statistical significance of a transition in the spectral lag data based on Lorentz invariance violation (LIV) (for both sub-luminal and super-luminal propagation) using Bayesian model selection. We use two different parametric functions to model the null hypothesis
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On the dynamics of a dark sector coupling J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-09-21 Weiqiang Yang, Supriya Pan, Olga Mena, Eleonora Di Valentino
Interacting dark energy models may play a crucial role in explaining several important observational issues in modern cosmology and also may provide a solution to current cosmological tensions. Since the phenomenology of the dark sector could be extremely rich, one should not restrict the interacting models to have a coupling parameter which is constant in cosmic time, rather allow for its dynamical
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Intermittent behaviour in small CORSIKA showers J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-08-30 Tadeusz Wibig
In this work we are concerned with the quantitative study of correlations between charged particles: electrons/positrons and muons in small Extensive Air Showers. By “small”, we mean showers that are initiated by primary protons with energies of up to ∼1 TeV. We study the strength of these correlations with the help of the CORSIKA simulation program. The results show the ‘intermittent’ behaviour of
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Particle acceleration in self-driven turbulent reconnection J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-08-21 Jian-Fu Zhang, Siyao Xu, Alex Lazarian, Grzegorz Kowal
The theoretical prediction that magnetic reconnection spontaneously drives turbulence has been supported by magnetohydrodynamic (MHD) and kinetic simulations. While reconnection with externally driven turbulence is accepted as an effective mechanism for particle acceleration, the acceleration during the reconnection with self-driven turbulence is studied for the first time in this work. By using high-resolution
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Propagation of anisotropic gravitational and electromagnetic waves at very high energies J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-07-25 J. Mestra-Páez, Alvaro Restuccia, Francisco Tello-Ortiz
We analyze the dispersion relation for an anisotropic gravity-electromagnetic theory at very high energies. In particular for photons of very high energy. We start by introducing the anisotropic gravity-gauge vector field model. It is invariant under spacelike diffeomorphisms, time parametrization, and U(1) gauge transformations. It includes high-order spacelike derivatives as well as polynomial expressions
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Type Ia supernovae induced by primordial black holes from dark first-order phase transition J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-07-25 Pin-Jung Chen, Po-Yan Tseng
A primordial black hole (PBH) with mass 10−15≤MPBH/M⊙≤10−10 is currently beyond the sensitivity of both microlensing and black hole (BH) evaporation methods. A novel scenario has been proposed: When a PBH with mass 10−14≤MPBH/M⊙≤10−11 transits through a white dwarf (WD) made up of carbon and oxygen, Bondi-Hoyle-Lyttleton (BHL) accretion in a reactive medium creates a shock wave, which generates direct
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Inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-07-10 Sunny Vagnozzi
Various pulsar timing array (PTA) experiments (NANOGrav, EPTA, PPTA, CPTA, including data from InPTA) very recently reported evidence for excess red common-spectrum signals in their latest datasets, with inter-pulsar correlations following the Hellings-Downs pattern, pointing to a stochastic gravitational wave background (SGWB) origin. Focusing for concreteness on the NANOGrav signal (given that all
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The neutrino emissivity and the cooling energy resources by magnetic monopole in white dwarfs J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-07-05 Jing-Jing Liu, Dong-Mei Liu
Some typical low mass and high mass white dwarfs (WDs) are selected and the neutrino emissivity and the cooling energy resources problems are discussed. We present three models (I, II, III) to investigate the number of magnetic monopole (MM) captured, the luminosity, and the neutrino emissivity based on the MM catalytic nuclear decay. Model (I) mainly considers the effect of compression factor on thermonuclear
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New emergent observational constraints in f(Q,T) gravity model J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-06-19 S.H. Shekh, A. Bouali, Anirudh Pradhan, A. Beesham
In the current study, we inspect the late-time acceleration of the universe in f(Q,T) gravity. In this theory, Q represents the non-metricity term and with Tμν the energy-momentum tensor, with T its trace. To explore the solutions in the theory for the Friedmann-Lemaitre-Robertson-Walker (FLRW) model, we propose a new scale factor called the emergent scale factor, which yields the Hubble parameter
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Thermal properties of the core of magnetar J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-06-09 Trisha Sarkar, Shalu Yadav, Monika Sinha
During very early age of neutron stars, the core cools down faster compared to the crust creating a large thermal gradient in the interior of the star. During 10−100 years, a cooling wave propagates from the core to the crust causing the interior of the star to thermalize. During this duration thermal properties of the core material is of great importance to understand the dynamics of the interior
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The radio monitoring of the microquasar GRS 1915+105 with FAST J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-06-08 Peng-Fu Tian, Ping Zhang, Wei Wang, Pei Wang, Xiaohui Sun, Zheng Zheng
We report radio observations of the Galactic microquasar GRS 1915+105 with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the band of 1.0−1.5 GHz. The observations were performed in 2020 with a total duration of ∼ 3.5 hours. In this work, we developed the pipeline to perform the calibration of the radio flux density and polarization for the persistent emitting radio source GRS
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The massive black holes, high accretion rates, and non-tilted jet feedback, of jetted AGN triggered by secular processes J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-06-07 Chandra B. Singh, David Garofalo
That jetted active galactic nuclei (AGN) are also hosted in spiral galaxies is now well established. Our understanding of how such objects might fit in the radio loud AGN subclass has been described by Foschini and others over the past decade in that jets in spirals are weaker than those of radio galaxies and quasars because the black holes in spirals tend to be less massive. Recent data, however,
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No evidence for EDE from Planck data in extended scenarios J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-05-25 Emanuele Fondi, Alessandro Melchiorri, Luca Pagano
The latest data release from the ACT CMB experiment (in combination with previous WMAP data) shows evidence for an Early Dark Energy component at more than 3 standard deviations. The same conclusion has been recently shown to hold when temperature data from the Planck experiment limited to intermediate angular scales (l≤650) are included while it vanishes when the full Planck dataset is considered
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Short Gamma rays bursts from binary black holes merger J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-05-19 Shad Ali
In this paper, we introduced a model related to the astronomical events having the co-detection of GW associated with Short Gamma Ray Bursts (SGRBs). Study shows that the existence of magnetized accretion disks is responsible for creating the events of GWs associated with electromagnetic (EM) counterparts from binary BHs mergers. Our model leads from space-time instability to the emission of EM radiations
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Entropy as logarithmic term of the central charge and modified Friedmann equation in AdS/CFT correspondence J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-05-18 M. Bousder, E. Salmani, H. Ez-Zahraouy
This paper is about the extended thermodynamics of AdS black holes and its relation to CFT thermodynamics. The logarithmic term of the central charge is interpreted as black hole entropy. We have to obtain a modified Friedmann equation from the Smarr formula. We find that the AdS radius is the critical shadow radius. We obtain the Hawking-Bekenstein formula with logarithmic corrections, which depends
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Observationally constrained accelerating cosmological model with higher power of non-metricity and squared trace J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-04-24 A.S. Agrawal, B. Mishra, S.K. Tripathy
In this paper, a cosmological model of the Universe is presented in f(Q,T) gravity and the parameters are constrained by cosmological data sets. Initially, a generalised form of f(Q,T) model is used as f(Q,T)=−λ1Qm−λ2T2, where λ1, λ2 and m are model parameters. With some algebraic manipulation, the Hubble parameter is obtained in terms of redshift. Then, using MCMC analysis, the model parameters are
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Measurements of spin and orbital parameters in Cen X-3 by Insight-HXMT J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-03-31 Qi Liu, Wei Wang
We present a detailed temporal analysis for the eclipsing high-mass X-ray binary system Cen X-3 using the Insight-HXMT data in 2018 and 2020. Three consecutive and high statistic observations among data are used for the precise timing analysis. The pulse profiles are revealed to vary with energy and time. The pulse profiles for the 2018 observations showed a double peak in the low energy bands below
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Sensitivity to point-like sources of the ALTO atmospheric particle detector array, designed for 200 GeV–50 TeV γ-ray astronomy J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-03-31 M. Punch, M. Senniappan, Y. Becherini, G. Kukec Mezek, S. Thoudam, T. Bylund, J.-P. Ernenwein
In the context of atmospheric shower arrays designed for γ-ray astronomy and in the context of the ALTO project, we present: a study of the impact of heavier nuclei in the cosmic-ray background on the estimated γ-ray detection performance on the basis of dedicated Monte Carlo simulations, a method to calculate the sensitivity to a point-like source, and finally the required observation times to reach
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Gamma rays from nebulae around recurrent novae J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-03-30 W. Bednarek, J. Sitarek
Novae were discovered to emit transient γ rays during the period of several days to a few weeks after initial explosion, indicating presence of acceleration processes of particles in their expanding shells. In the case of recurrent novae, electrons can be in principle accelerated in the nova shells for the whole recurrence period of nova producing delayed γ ray emission as considered in Bednarek (2022)
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The reconstruction of constant jerk parameter with f(R,T) gravity J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-03-15 Anirudh Pradhan, Gopikant Goswami, Aroonkumar Beesham
In this work, we have developed an FLRW type model of a universe which displays transition from deceleration in the past to the acceleration at the present. For this, we have considered field equations of f(R,T) gravity and have taken f(R,T)=R+2λT, λ being an arbitrary constant. We have estimated the λ parameter in such a way that the transition red shift is found similar in the deceleration parameter
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High-energy neutrino fluxes from hard-TeV BL Lacs J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-02-28 E. Aguilar-Ruiz, N. Fraija, A. Galván-Gámez
Blazars have been pointed out as promising high-energy (HE) neutrinos sources, although the mechanism is still under debate. The blazars with a hard-TeV spectrum, which leptonic models can hardly explain, can be successfully interpreted in the hadronic scenarios. Recently, Aguilar et al. proposed a lepto-hadronic two-zone model to explain the multi-wavelength observations of the six best-known extreme
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Energetic requirements of the gamma-ray emission from pulsars: A nonparametric analysis of the data in the Fermi-LAT 12-Year Catalog J. High Energy Astrophys. (IF 3.8) Pub Date : 2023-01-21 Houshang Ardavan
The prevalent view that the radio-loud gamma-ray pulsars have gamma-ray luminosities that exceed their radio luminosities by several orders of magnitude is based on the assumption that the decay with distance of their gamma-ray fluxes obeys the inverse-square law as does that of their radio fluxes. The results presented here, of testing the hypothesis of independence of luminosities and distances of
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Synchrotron self-compton emission in the two-component jet model for gamma-ray bursts J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-12-22 Yuri Sato, Kaori Obayashi, B. Theodre Zhang, Shuta J. Tanaka, Kohta Murase, Yutaka Ohira, Ryo Yamazaki
Gamma-ray bursts (GRBs) are intense bursts of high-energy photons (prompt emissions) caused by relativistic jets. After the emissions, multi-wavelength afterglows, from radio to very-high-energy (VHE) gamma-ray, last for more than a few days. In the past three years, the VHE gamma-ray photons from four GRBs (GRBs 180720B, 190114C, 190829A and 201216C) were detected by ground-based Imaging Atmospheric
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Classification of pulsar glitch amplitudes using extreme deconvolution J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-12-19 Swetha Arumugam, Shantanu Desai
We carry out a classification of the glitch amplitudes of radio pulsars using Extreme Deconvolution technique based on the Gaussian Mixture Model, where the observed uncertainties in the glitch amplitudes (Δνν) are taken into account. Our dataset consists of 699 glitches from 238 pulsars. We then use information theory criteria such as AIC and BIC to determine the optimum number of glitch classes.
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Dependency of optical/UV parameters on X-ray spectral index in AGNs J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-12-15 D. Nour, K. Sriram
The study of Active Galactic Nuclei (AGNs) is vital in order to understand their respective nuclei bounded activity primarily triggered by the accretion disk and the associated corona. The hard X-ray emission characterised by the spectral index Γ emitted by these sources in 2-10 keV band ionizes the nearby physical features like disk, BLR, NLR and provides a radiative configuration. However, based
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Thermodynamical aspects of Bianchi type-I Universe in quadratic form of f(Q) gravity and observational constraints J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-12-09 M. Koussour, S.H. Shekh, M. Govender, M. Bennai
In this paper, we discuss the Bianchi type-I cosmological model in the framework of symmetric teleparallel gravity say f(Q) gravity in which the non-metricity term Q is responsible for the gravitational interaction. We consider a special form of the f(Q) function which can be cast as f(Q)=λQn, where λ and n both are the dynamical model parameters. Such a choice can be viewed as a hybrid scale factor
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Accretion disk wind during the outburst of the stellar-mass black hole MAXI J1348-630 J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-12-12 Hanji Wu, Wei Wang, Na Sai
We analyzed two observations of the low-mass black hole X-ray binary MAXI J1348-630 from Nuclear Spectroscopic Telescope Array (NuSTAR) during low hard state and hard intermediate state in the 2019 outburst. The reflection components are found in the X-ray spectra, and the spectral fittings give an inclination angle of ∼25∘−35∘ for the binary system, and there is an absorption line around ∼7 keV coming
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Dissipative unified dark fluid: Observational constraints J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-12-01 Esraa Ali Elkhateeb, Mahmoud Hashim
We adopt a standard FRW cosmology with a unified scenario, where the usual dark matter and dark energy sectors are replaced by a single dissipative unified dark fluid (DUDF). The equation of state of such fluid can asymptote between two power laws. As a result, it enables fluid to have a smooth transition from dust at early times to dark energy at late times. The dissipation is represented by a bulk
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Foreword J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-11-21 Giovanni Pareschi, Patrizia Caraveo
Abstract not available
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X-ray properties of high-redshift Radio Loud and Radio Quiet Quasars observed by Chandra J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-10-31 F. Shaban, A. Siemiginowska, R.M. Suleiman, M.S. El-Nawawy, A. Ali
We performed a study of high redshift (z>2) quasars, looking for the main differences between Radio Loud Quasars (RLQ) and Radio Quiet Quasars (RQQ) in the X-ray band. Our sample of 472 RQQ and 81 RLQ was selected by cross-matching the SDSS DR7 quasars catalog with the Chandra Source Catalog. We computed the X-ray luminosity for the two samples and confirmed the X-ray luminosity excess of RLQ over
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Interacting dark energy in curved FLRW spacetime from Weyl Integrable Spacetime J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-10-19 S. Chatzidakis, A. Giacomini, P.G.L. Leach, G. Leon, A. Paliathanasis, Supriya Pan
In the present article, we show that a simple modification to the Einstein-Hilbert action can explain the possibility of mutual interaction between the cosmic fluids. That is achieved considering the Weyl Integrable Spacetime in the background of a nonflat Friedmann-Lemaître-Robertson-Walker geometry for the universe. We perform the dynamical system analysis of the underlying cosmological scenario
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How unique are pulsar wind nebulae models? Implementation of a multi-parameter, automatic fitting for time-dependent spectra J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-09-28 J. Martin, D.F. Torres
Due to the computational cost of calculating a great number of variations of the parameters, detailed radiative models of pulsar wind nebulae (PWNe) do not usually contain fitting algorithms. As a consequence, most of the models in the literature are, in fact, qualitative fits based on visual inspection. This is particularly true when complex, time-dependent models are considered. Motivated by improvements
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Special cases of the multi-measure model – Understanding the prolonged inflation J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-09-21 Denitsa Staicova
The multi-measure model (MMM), in which one modifies the action to include both the Riemannian measure and a non-Riemannian one, has proven to be able to produce viable Universe evolution scenarios. In this article we consider two special cases of the multi-measure model, in which we first decouple the two kinetic terms in the Lagrangian entirely and later remove the dark charge of the model. We show
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An extensive analysis of Schwarzschild exterior solution J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-09-13 Devanarayanan Rajeeb Kumar, Nibedita Chowdhury, S.D. Pathak, Umang Kumar, Manabendra Sharma, Vikash Kumar Ojha
We pursue a detailed analysis of the Schwarzschild geometry around a spherically symmetric, non-rotating, uncharged source and aim to construct the Schwarzschild metric by considering trigonometric, hyperbolic and logarithmic functions of position and time and solving the Einstein field equation. We investigate whether the Schwarzschild exterior solution is indeed independent of the choice of the nature
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High-energy and ultra-high-energy neutrinos: A Snowmass white paper J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-08-08 Markus Ackermann, Mauricio Bustamante, Lu Lu, Nepomuk Otte, Mary Hall Reno, Stephanie Wissel, Markus Ackermann, Sanjib K. Agarwalla, Jaime Alvarez-Muñiz, Rafael Alves Batista, Carlos A. Argüelles, Mauricio Bustamante, Brian A. Clark, Austin Cummings, Sudipta Das, Valentin Decoene, Peter B. Denton, Damien Dornic, Shiqi Yu
Astrophysical neutrinos are excellent probes of astroparticle physics and high-energy physics. With energies far beyond solar, supernovae, atmospheric, and accelerator neutrinos, high-energy and ultra-high-energy neutrinos probe fundamental physics from the TeV scale to the EeV scale and beyond. They are sensitive to physics both within and beyond the Standard Model through their production mechanisms
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Gravitational waves with dark energy J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-08-05 Jafar Khodagholizadeh
In this article, we study the tensor mode equation of perturbation in the presence of nonzero−Λ as dark energy, the dynamic nature of which depends on the Hubble parameter H and/or its time derivative. Dark energy, according to the total vacuum contribution, has a slight effect during the radiation-dominated era, but it reduces the squared amplitude of gravitational waves (GWs) up to 60% for the wavelengths
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Implications for the Hubble tension from the ages of the oldest astrophysical objects J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-08-02 Sunny Vagnozzi, Fabio Pacucci, Abraham Loeb
We use the ages of old astrophysical objects (OAO) in the redshift range 0≲z≲8 as stringent tests of the late-time cosmic expansion history. Since the age of the Universe at any redshift is inversely proportional to H0, requiring that the Universe be older than the oldest objects it contains at any redshift, provides an upper limit on H0. Using a combination of galaxies imaged from the CANDELS program
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Study of general relativistic shocks and their propagation in neutron stars J. High Energy Astrophys. (IF 3.8) Pub Date : 2022-08-02 Ritam Mallick, Anshuman Verma
Astrophysical shocks are very common and are interesting as they are responsible for particle acceleration in supernovas, blazers, and neutron stars. In this work, we study general relativistic shocks in which the shock front is at rest. We derive the jump conditions and the Taub adiabat equation for both the space-like and time-like shocks. We solve these equations for a neutron star where the shock