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Bhjet: a public multi-zone, steady state jet + thermal corona spectral model: Accreting black holes are sources of major interest in astronomy, particular those launching jets because of their ability to accelerate particles, and dramatically affect their surrounding environment up to very large distances. The spatia...
astro-ph_HE
The Long-term Monitoring Results of Insight-HXMT in the First 4 Yr Galactic Plane Scanning Survey: The first X-ray source catalog of Insight-HXMT Galactic Plane (|b|<10deg) Scanning Survey (GPSS) is presented based on the data accumulated from June 2017 to August 2021. The 4 yr limit sensitivities at main energy band...
astro-ph_HE
Enhancing gravitational wave astronomy with galaxy catalogues: Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key research direction in multi-messenger astronomy, will provide deep insight into the astrophysics of a vast range of astronomical phenomena. Uncertainties in the source sky locatio...
astro-ph_HE
Massive White Dwarfs in the Galactic Center: A Chandra X-ray Spectroscopy of Cataclysmic Variables: Previous X-ray observations toward the Nuclear Star Cluster (NSC) at the Galactic center have discovered thousands of point sources, most of which were believed to be cataclysmic variables (CVs), i.e., a white dwarf (W...
astro-ph_HE
Nitrogen K-shell photoabsorption: Reliable atomic data have been computed for the spectral modeling of the nitrogen K lines, which may lead to useful astrophysical diagnostics. Data sets comprise valence and K-vacancy level energies, wavelengths, Einstein $A$-coefficients, radiative and Auger widths and K-edge photoion...
astro-ph_HE
Exploring binary-neutron-star-merger scenario of short-gamma-ray bursts by gravitational-wave observation: We elucidate the feature of gravitational waves (GWs) from binary neutron star merger collapsing to a black hole by general relativistic simulation. We show that GW spectrum imprints the coalescence dynamics, fo...
astro-ph_HE
Outflow-Driven Transients from the Birth of Binary Black Holes I: Tidally-Locked Secondary Supernovae: We propose a new type of electromagnetic transients associated with the birth of binary black holes (BBHs), which may lead to merger events accompanied by gravitational waves in $\sim0.1-1$ Gyr. We consider the newb...
astro-ph_HE
A NICER view of PSR J0030+0451: evidence for a global-scale multipolar magnetic field: Recent modeling of NICER observations of thermal X-ray pulsations from the surface of the isolated millisecond pulsar PSR J0030+0451 suggests that the hot emitting regions on the pulsar's surface are far from antipodal, which is at...
astro-ph_HE
Optical Spectroscopy of Bright Fermi LAT Blazars: We report on HET and Palomar 5 m spectroscopy of recently identified $\gamma$-ray blazars in the {\it Fermi} LAT Bright Source List. These data provide identifications for 10 newly discovered $\gamma$-ray flat spectrum radio quasars (FSRQ) and six new BL Lacs plus impro...
astro-ph_HE
A multi-wavelength study of the gamma-ray binary candidate HESS J1832-093: We investigate the nature of the unidentified very-high-energy (VHE) gamma-ray object, HESS J1832-093, in a multi-wavelength context. Based on X-ray variability and spectral index ($\Gamma_X\sim\,1.5$), and its broad-band spectrum (which was r...
astro-ph_HE
Diverse Properties of Interstellar Medium Embedding Gamma-Ray Bursts at the Epoch of Reionization: Analysis is performed on ultra-high resolution large-scale cosmological radiation-hydrodynamic simulations to, for the first time, quantify the physical environment of long-duration gamma-ray bursts (GRBs) at the epoch ...
astro-ph_HE
Multi-wavelength observations of Isolated Neutron Stars: Almost 30 Isolated Neutron Stars (INSs) of different flavours have been identified at optical, ultraviolet, or infrared (UVOIR) wavelengths. Here, I present a short review of the historical background and describe the scientific impact of INS observations in the ...
astro-ph_HE
Hot disk of the Swift J0243.6+6124 revealed by Insight-HXMT: We report on analysis of observations of the bright transient X-ray pulsar \src obtained during its 2017-2018 giant outburst with Insight-HXMT, \emph{NuSTAR}, and \textit{Swift} observatories. We focus on the discovery of a sharp state transition of the timin...
astro-ph_HE
QCD, Gravitational Waves, and Pulsars: Investigations of the phase diagram of quantum chromodynamics (QCD) have revealed that exotic new phases, the so called {\it color superconducting phases}, may arise at very high baryon densities. It is speculated that these exotic phases may arise in the cores of neutron stars. F...
astro-ph_HE
Californium-254 and kilonova light curves: Neutron star mergers offer unique conditions for the creation of the heavy elements and additionally provide a testbed for our understanding of this synthesis known as the $r$-process. We have performed dynamical nucleosynthesis calculations and identified a single isotope, $^...
astro-ph_HE
On the approximation of the black hole shadow with a simple polar curve: A black hole embedded within a bright, optically thin emitting region imprints a nearly circular "shadow" on its image, corresponding to the observer's line-of-sight into the black hole. The shadow boundary depends on the black hole's mass and spi...
astro-ph_HE
The Euclidean distribution of Fast Radio Bursts: We investigate whether current data on the distribution of observed flux densities of Fast Radio Bursts (FRBs) are consistent with a constant source density in Euclidean space. We use the number of FRBs detected in two surveys with different characteristics along with th...
astro-ph_HE
Suzaku investigation into the nature of the nearest ultraluminous X-ray source, M33 X-8: The X-ray spectrum of the nearest ultraluminous X-ray source, M33 X-8, obtained by Suzaku during 2010 January 11 -- 13, was closely analyzed to examine its nature. It is, by far, the only data with the highest signal statistic in...
astro-ph_HE
Fast TeV variability from misaligned minijets in the jet of M87: The jet of the radio galaxy M87 is misaligned, resulting in a Doppler factor delta~1 for emission of plasma moving parallel to the jet. This makes the observed fast TeV flares on timescales of t_v~5R_g/c harder to understand as emission from the jet. In p...
astro-ph_HE
Favorable conditions for heavy element nucleosynthesis in rotating proto-magnetar winds: The neutrino-driven wind cooling phase of proto-neutron stars (PNSs) follows successful supernovae. Wind models without magnetic fields or rotation fail to achieve the necessary conditions for production of the third $r$-process ...
astro-ph_HE
Magnetic Fields, Relativistic Particles, and Shock Waves in Cluster Outskirts: It is only now, with low-frequency radio telescopes, long exposures with high-resolution X-ray satellites and gamma-ray telescopes, that we are beginning to learn about the physics in the periphery of galaxy clusters. In the coming years, ...
astro-ph_HE
Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz: Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) wh...
astro-ph_HE
Did a Kilonova Set Off in Our Galactic Backyard 3.5 Myr ago?: The recent detection of the live isotopes $^{60}{\rm Fe}$ and $^{244}{\rm Pu}$ in deep ocean sediments dating back to the past 3-4 Myr poses a serious challenge to the identification of their production site(s). While $^{60}{\rm Fe}$ is usually attributed to...
astro-ph_HE
The Discovery of the Most Accelerated Binary Pulsar: Pulsars in relativistic binary systems have emerged as fantastic natural laboratories for testing theories of gravity, the most prominent example being the double pulsar, PSR J0737$-$3039. The HTRU-South Low Latitude pulsar survey represents one of the most sensitive...
astro-ph_HE
NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-ray Source Candidate in NGC 5643: We present two NuSTAR observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Ne...
astro-ph_HE
Absorption of GRB X-ray Afterglows by The Missing Baryons: Confronting Observations with Cosmological Simulations: A large fraction of the baryons at low redshift are undetected, and likely reside in the tenuous, hot intergalactic medium (IGM). One way to probe the missing baryons is through their absorption of brigh...
astro-ph_HE
Instability of twisted magnetar magnetospheres: We present three-dimensional force-free electrodynamics simulations of magnetar magnetospheres that demonstrate the instability of certain degenerate, high energy equilibrium solutions of the Grad-Shafranov equation. This result indicates the existence of an unstable bran...
astro-ph_HE
The link between short Gamma-ray bursts and Gravitational Waves: perspectives for the THESEUS mission: The knowledge of the class of short Gamma-Ray Bursts (GRBs), characterised by a duration of the gamma-ray emission $\leq 2$ s, experienced an impressive boost in the last decade. In particular, the discovery of shor...
astro-ph_HE
Time of Flight and Supernova Progenitor Effects on the Neutrino Halo: We argue that the neutrino halo, a population of neutrinos that have undergone direction-changing scattering in the stellar envelope of a core-collapse supernova (CCSNe), is sensitive to neutrino emission history through time of flight. We show that ...
astro-ph_HE
X-ray counterpart of gravitational waves due to binary neutron star mergers: light curves, luminosity functions, and event rate densities: Zhang (2013) proposed a type of GRB-less X-ray transient associated with double neutron star (NS-NS) mergers under the conjecture of a rapidly-spinning magnetar merger product wit...
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Long-term monitoring of LS I+61303 with INTEGRAL: LS I+61303 is one of the few high-mass X-ray binaries that have been recently observed at TeV and GeV energies. Here we investigate the hard X-ray spectral and timing properties of this source using the IBIS/ISGRI instrument on-board the INTEGRAL satellite. We carry out...
astro-ph_HE
The role of metallicity in high mass X-ray binaries in galaxy formation models: Recent theoretical works claim that high-mass X-ray binaries (HMXBs) could have been important sources of energy feedback into the interstellar and intergalactic media, playing a major role in the reionization epoch. A metallicity depende...
astro-ph_HE
Multiwavelength behaviour of the blazar 3C279: decade-long study from $γ$-ray to radio: We report the results of decade-long (2008-2018) $\gamma$-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, $\it{Fermi}$ and $\it{Swift}$ data, as well as polarimetric and spectroscopic data. The X-ray and $...
astro-ph_HE
Type Ic Supernova of a 22 $\text{M}_{\odot}$ Progenitor: Type Ic supernovae (SNe Ic) are a sub-class of core-collapse supernovae that exhibit no helium or hydrogen lines in their spectra. Their progenitors are thought to be bare carbon-oxygen cores formed during the evolution of massive stars that are stripped of their...
astro-ph_HE
ASAS-SN search for optical counterparts of gravitational-wave events from the third observing run of Advanced LIGO/Virgo: We report on the search for electromagnetic counterparts to the nine gravitational-wave events with a $>$60\% probability of containing a neutron star during the third (O3) LIGO-Virgo Collaboratio...
astro-ph_HE
Star formation, supernovae, iron, and alpha: consistent cosmic and Galactic histories: Recent versions of the observed cosmic star-formation history (SFH) have resolved an inconsistency with the stellar mass density history. We show that the revised SFH also scales up the delay-time distribution (DTD) of Type Ia supe...
astro-ph_HE
Dissipation of the striped pulsar wind: Rapidly rotating neutron stars blow a relativistic, magnetized wind mainly composed of electron-positron pairs. The free expansion of the wind terminates far from the neutron star where a weakly magnetized pulsar wind nebula forms, implying efficient magnetic dissipation somewher...
astro-ph_HE
Acceleration and propagation of ultra high energy cosmic rays: We review the physics of the highest energy cosmic rays. The discovery of their sources, still unknown, will reveal the most energetic astrophysical objects in the universe and could unveil new physics beyond the standard model of particle physics. We discu...
astro-ph_HE
CLUES on Fermi-LAT prospects for the extragalactic detection of munuSSM gravitino Dark Matter: The munuSSM is a supersymmetric model that has been proposed to solve the problems generated by other supersymmetric extensions of the standard model of particle physics. Given that R-parity is broken in the munuSSM, the gr...
astro-ph_HE
LeHaMoC: a versatile time-dependent lepto-hadronic modeling code for high-energy astrophysical sources: Recent associations of high-energy neutrinos with active galactic nuclei (AGN) have revived the interest in leptohadronic models of radiation from astrophysical sources. The rapid increase in the amount of acquired...
astro-ph_HE
AT2017gfo: an anisotropic and three-component kilonova counterpart of GW170817: The detection of a kilo/macronova electromagnetic counterpart (AT2017gfo) of the first gravitational wave signal compatible with the merger of two neutron stars (GW170817) has confirmed the occurrence of r-process nucleosynthesis in this ...
astro-ph_HE
Bondi on spherically symmetric accretion: Hermann Bondi's 1952 paper "On spherically symmetrical accretion" is recognized as one of the foundations of accretion theory. Although Bondi later remarked that it was "not much more than an examination exercise", his mathematical analysis of spherical accretion on to a point ...
astro-ph_HE
Indications of non-conservative mass-transfer in AMXPs: Context. Since the discovery of the first Accreting Millisecond X-ray Pulsar SAX J1808.4-3658 in 1998, the family of these sources kept growing on. Currently, it counts 22 members. All AMXPs are transients with usually very long quiescence periods, implying that m...
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The First Two Years of Electromagnetic Follow-Up with Advanced LIGO and Virgo: We anticipate the first direct detections of gravitational waves (GWs) with Advanced LIGO and Virgo later this decade. Though this groundbreaking technical achievement will be its own reward, a still greater prize could be observations of ...
astro-ph_HE
Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44: Aims: A hard X-ray shortage, implying the cooling of the corona, was observed during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart from these four sources, we investigate here an atoll sample, in which the number of bursts...
astro-ph_HE
The Role of Fission in Neutron Star Mergers and its Impact on the r-Process Peaks: Comparing observational abundance features with nucleosynthesis predictions of stellar evolution or explosion simulations can scrutinize two aspects: (a) the conditions in the astrophysical production site and (b) the quality of the nu...
astro-ph_HE
Supergiant, fast, but not so transient 4U 1907+09: We have investigated the dipping activity observed in the high-mass X-ray binary 4U 1907+09 and shown that the source continues to pulsate in the "off" state, noting that the transition between the "on" and "off" states may be either dip-like or flare-like. This behavi...
astro-ph_HE
The Fermi Haze: A Gamma-Ray Counterpart to the Microwave Haze: The Fermi Gamma-Ray Space Telescope reveals a diffuse inverse Compton signal in the inner Galaxy with a similar spatial morphology to the microwave haze observed by WMAP, supporting the synchrotron interpretation of the microwave signal. Using spatial templ...
astro-ph_HE
A Systematic Search for Periodically Varying Quasars in Pan-STARRS1: An Extended Baseline Test in Medium Deep Survey Field MD09: We present a systematic search for periodically varying quasars and supermassive black hole binary (SMBHB) candidates in the Pan-STARRS1 (PS1) Medium Deep Survey's MD09 field. From a color-...
astro-ph_HE
Identification of AGN in the XMM-Newton X-ray survey of the SMC: Context: Finding Active Galactic Nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it is only recent...
astro-ph_HE
A dispersion excess from pulsar wind nebulae and supernova remnants: Implications for pulsars and FRBs: Young pulsars and the pulsar wind nebulae (PWNe) or supernova remnants (SNRs) that surround them are some of the most dynamic and high-powered environments in our Universe. With the rise of more sensitive observati...
astro-ph_HE
Returning radiation in strong gravity around black holes: Reverberation from the accretion disc: We study reflected X-ray emission that returns to the accretion disc in the strong gravitational fields around black holes using General Relativistic ray tracing and radiative transfer calculations. Reflected X-rays that ...
astro-ph_HE
Multiwavelength flaring activity of PKS1510-089: Aims: In this work, we analyse the multiwavelength brightness variations and flaring activity of FSRQ PKS1510-089, aiming to constrain the position of the emission sources. Methods: We report 7 mm (43 GHz) radio and R-band polarimetric observations of PKS1510-089. The ...
astro-ph_HE
Equation-of-State Constraints on the Neutron-Star Binding Energy and Tests of Binary Formation Scenarios: The second supernova that forms double-neutron-star systems is expected to occur in a progenitor that is ultra-stripped due to binary interactions. Thus, the secondary neutron star's mass as well as the post-supe...
astro-ph_HE
Evidence of a non-conservative mass transfer in the ultra-compact X-ray source XB 1916-053: The dipping source XB 1916-053 is a compact binary system with an orbital period of 50 min harboring a neutron star. Using ten new {\it Chandra} observations and one {\it Swift/XRT} observation, we are able to extend the basel...
astro-ph_HE
The Variable Pulsar Wind Nebula of PSR J1809-1917: PSR J1809-1917 is a young ($\tau=51$ kyr) energetic ($\dot{E}=1.8\times10^{36}$ erg s$^{-1}$) radio pulsar powering a pulsar wind nebula (PWN). We report on the results of three Chandra X-ray Observatory observations which show that the PWN consists of a small ($\sim 2...
astro-ph_HE
Magnetosphere of an orbiting neutron star: We conduct force-free simulations of a single neutron star undergoing orbital motion in flat spacetime, mimicking the trajectory of the star about the center of mass on a compact binary system. Our attention is focused on the kinetic energy being extracted from the orbit by th...
astro-ph_HE
The Redshift Dependence of the Radio Flux of Gamma-Ray Bursts and Their Host Galaxies: Using multiwavelength observations of radio afterglows, we confirm the hypothesis that the flux density of gamma-ray bursts (GRBs) at a fixed observing frequency is invariable when the distance of the GRBs increases, which means th...
astro-ph_HE
Searching for TeV Dark Matter in Irregular dwarf galaxies with HAWC Observatory: We present the results of dark matter (DM) searches in a sample of 31 dwarf irregular (dIrr) galaxies within the field of view of the HAWC Observatory. dIrr galaxies are DM dominated objects, which astrophysical gamma-ray emission is est...
astro-ph_HE
From Observations near the Earth to the Local Interstellar Spectra: Propagation of cosmic rays (CRs) from their sources to the observer is described mainly as plain diffusion at high energies, while at lower energies there are other physical processes involved, both in the interstellar space and in the heliosphere. The...
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The potential role of binary neutron star merger afterglows in multimessenger cosmology: Binary neutron star mergers offer a new and independent means of measuring the Hubble constant $H_0$ by combining the gravitational-wave inferred source luminosity distance with its redshift obtained from electromagnetic follow-u...
astro-ph_HE
A Wolf-Rayet-like progenitor of supernova SN 2013cu from spectral observations of a wind: The explosive fate of massive stripped Wolf-Rayet (W-R) stars is a key open question in stellar physics. An appealing option is that hydrogen-deficient W-R stars are the progenitors of some H-poor supernova (SN) explosions of Ty...
astro-ph_HE
Peculiarly Narrow SED of GRB 090926B with MAXI and Fermi/GBM: The monitor of all-sky X-ray image (MAXI) Gas Slit Camera (GSC) on the International Space Station (ISS) detected a gamma-ray burst (GRB) on 2009, September 26, GRB\,090926B. This GRB had extremely hard spectra in the X-ray energy range. Joint spectral fitti...
astro-ph_HE
Radio Analysis of SN 2004C Reveals an Unusual CSM Density Profile as a Harbinger of Core Collapse: We present extensive multi-frequency VLA and VLBA observations of the radio-bright supernova (SN) IIb SN 2004C that span $\sim(40-2793)$ days post-explosion. We interpret the temporal evolution of the radio spectral ene...
astro-ph_HE
Consequences of a Dark Disk for the Fermi and PAMELA Signals in Theories with a Sommerfeld Enhancement: Much attention has been given to dark matter explanations of the PAMELA positron fraction and Fermi electronic excesses. For those theories with a TeV-scale WIMP annihilating through a light force-carrier, the asso...
astro-ph_HE
Chandra Phase-Resolved Spectroscopy of the High Magnetic Field Pulsar B1509-58: We report on a timing and spectral analysis of the young, high magnetic field rotation-powered pulsar (RPP) B1509-58 using Chandra continuous-clocking mode observation. The pulsar's X-ray light curve can be fit by the two Gaussian compone...
astro-ph_HE
Evolution of the radio - X-ray coupling throughout an entire outburst of Aquila X-1: The 2009 November outburst of the neutron star X-ray binary Aquila X-1 was observed with unprecedented radio coverage and simultaneous pointed X-ray observations, tracing the radio emission around the full X-ray hysteresis loop of th...
astro-ph_HE
X-ray Pulsations from the region of the Supergiant Fast X-ray Transient IGR J17544-2619: Phase-targeted RXTE observations have allowed us to detect a transient 71.49 \pm 0.02 s signal that is most likely to be originating from the supergiant fast X-ray transient IGR J17544-2619. The phase-folded light curve shows a p...
astro-ph_HE
StrayCats: A catalog of NuSTAR Stray Light Observations: We present StrayCats: a catalog of NuSTAR stray light observations of X-ray sources. Stray light observations arise for sources 1--4$^{\circ}$ away from the telescope pointing direction. At this off-axis angle, X-rays pass through a gap between optics and apertur...
astro-ph_HE
Spectral and polarization properties of black hole accretion disc emission: including absorption effects: The study of radiation emitted from black hole accretion discs represents a crucial way to understand the main physical properties of these sources, and in particular the black hole spin. Beside spectral analysis...
astro-ph_HE
Modelling Continuum Reverberation in AGN: A Spectral-Timing Analysis of the UV Variability Through X-ray Reverberation in Fairall 9: Continuum reverberation mapping of AGN can provide new insight into the nature and geometry of the accretion flow. Some of the X-rays from the central corona irradiating the disc are ab...
astro-ph_HE
The chemical enrichment of long-GRB nurseries up to z=2: We investigate the existence of a metallicity threshold for the production of long gamma-ray bursts (LGRBs). We used the host galaxies of the Swift/BAT6 sample of LGRBs. We considered the stellar mass, star formation rate (SFR), and metallicity determined from th...
astro-ph_HE
Fermi Observation of the transitional pulsar binary XSS J12270-4859: Because of the disappearance of its accretion disk since the time period around 2012 November--December, XSS J12270-4859 has recently been identified as, in addition to PSR J1023+0038, another transitional millisecond pulsar binary. We have carried ou...
astro-ph_HE
Cosmic ray Transport in Magnetohydrodynamic turbulence: This paper studies cosmic ray (CR) transport in magneto hydrodynamic (MHD) turbulence. CR transport is strongly dependent on the properties of the magnetic turbulence. We perform test particle simulations to study the interactions of CR with both total MHD turbule...
astro-ph_HE
Radio quasars and the link with GAIA: Modeling VLBI ejections of nuclei of extragalactic radio sources, indicates that their nuclei contain a binary black hole system. One can derive the distance and the positions of the two black holes in the plane of the sky. We can also use the RMS of the time series of the ICRF2 su...
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Observations of the Very Young Type Ia Supernova 2019np with Early-excess Emission: Early-time radiative signals from type Ia supernovae (SNe Ia) can provide important constraints on the explosion mechanism and the progenitor system. We present observations and analysis of SN 2019np, a nearby SN Ia discovered within ...
astro-ph_HE
Mass composition of ultra-high-energy cosmic rays with the Telescope Array Surface Detector Data: The results on ultra-high-energy cosmic rays (UHECR) mass composition obtained with the Telescope Array surface detector are presented. The analysis employs the boosted decision tree (BDT) multivariate analysis built upo...
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A Model for Pair Production Limit Cycles in Pulsar Magnetospheres: It was recently proposed that the electric field oscillation as a result of self-consistent $e^{\pm}$ pair production may be the source of coherent radio emission from pulsars. Direct Particle-in-Cell (PIC) simulations of this process have shown that th...
astro-ph_HE
Magnetar Activity via the Density-Shear Instability in Hall-MHD: We investigate the density-shear instability in Hall-MHD via numerical simulation of the full non-linear problem, in the context of magnetar activity. We confirm the development of the instability of a plane-parallel magnetic field with an appropriate int...
astro-ph_HE
An Ultra-Fast X-ray Disk Wind in the Neutron Star Binary GX 340+0: We present a spectral analysis of a brief Chandra/HETG observation of the neutron star low-mass X-ray binary GX~340+0. The high-resolution spectrum reveals evidence of ionized absorption in the Fe K band. The strongest feature, an absorption line at app...
astro-ph_HE
The blazar TXS 0506+056 associated with a high-energy neutrino: insights into extragalactic jets and cosmic ray acceleration: A neutrino with energy of $\sim$290 TeV, IceCube-170922A, was detected in coincidence with the BL Lac object TXS~0506+056 during enhanced gamma-ray activity, with chance coincidence being reje...
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Theoretical Delay Time Distributions: We briefly discuss the method of population synthesis to calculate theoretical delay time distributions of type Ia supernova progenitors. We also compare the results of the different research groups and conclude that although one of the main differences in the results for single de...
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Mass Ratios of Merging Double Neutron Stars as Implied by the Milky Way Population: Of the seven known double neutron stars (DNS) with precisely measure masses in the Milky Way that will merge within a Hubble time, all but one has a mass ratio, $q$, close to unity. Recently, precise measurements of three post-Kepleri...
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Obscured $pp$-channel neutrino sources: We explore the possibility that the astrophysical neutrinos are produced in $pp$-interactions with a gas cloud near the source acting as a beam dump, which is sufficiently dense to significantly attenuate the associated gamma-ray flux through pair-production on this gas. In this ...
astro-ph_HE
Wide band observations of the X-ray burster GS 1826-238: GS 1826-238 is a well-studied X-ray bursting neutron star in a low mass binary system. Thermal Comptonisation by a hot electron cloud is a widely accepted mechanism accounting for its high energy emission, while the nature of most of its soft X-ray output is not ...
astro-ph_HE
High Energy Neutrinos from the Gravitational Wave event GW150914 possibly associated with a short Gamma-Ray Burst: High-energy neutrino (HEN) and gravitational wave (GW) can probe astrophysical sources in addition to electromagnetic observations. Multimessenger studies can reveal nature of the sources which may not b...
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Simulations of Magnetic Fields in Tidally-Disrupted Stars: We perform the first magnetohydrodynamical simulations of tidal disruptions of stars by supermassive black holes. We consider stars with both tangled and ordered magnetic fields, for both grazing and deeply disruptive encounters. When the star survives disrupti...
astro-ph_HE
Spectro-Timing Analysis of a highly variable narrow-line Seyfert 1 galaxy NGC 4748 with AstroSat and XMM-Newton: We present a detailed timing and spectral study of an extremely variable narrow-line Seyfert~1 galaxy NGC 4748 using observations in the year 2017 and 2014 performed with AstroSat and XMM-Newton, respectiv...
astro-ph_HE
The Konus-Wind catalog of gamma-ray bursts with known redshifts. II. Waiting mode bursts simultaneously detected by Swift/BAT: In the Second part of The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts (first part: Tsvetkova et al. 2017; T17), we present the results of a systematic study of gamma-ray burst...
astro-ph_HE
Massive non-thermal radio emitters: new data and their modelling: During recent years some non-thermal radio emitting OB stars have been discovered to be binary, or multiple systems. The non-thermal emission is due to synchrotron radiation that is emitted by electrons accelerated up to high energies. The electron accel...
astro-ph_HE
Puffy accretion disks: sub-Eddington, optically thick, and stable: We report on a new class of solutions of black hole accretion disks that we have found through three-dimensional, global, radiative magnetohydrodynamic simulations in general relativity. It combines features of the canonical thin, slim and thick disk ...
astro-ph_HE
Cosmic ray Transport in Magnetohydrodynamic turbulence: This paper studies cosmic ray (CR) transport in magneto hydrodynamic (MHD) turbulence. CR transport is strongly dependent on the properties of the magnetic turbulence. We perform test particle simulations to study the interactions of CR with both total MHD turbule...
astro-ph_HE
The Spin of New Black Hole Candidate: MAXI J1803-298 Observed by NuSTAR and NICER: MAXI J1803-298, a newly-discovered Galactic transient and black hole candidate, was first detected by \emph{MAXI}/GSC on May 1st, 2021. In this paper, we present a detailed spectral analysis of MAXI J1803-298. Utilizing the X-ray refle...
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Discovery of a recurrent spectral evolutionary cycle in the ultra-luminous X-ray sources Holmberg II X-1 and NGC 5204 X-1: Most ultra-luminous X-ray sources (ULXs) are now thought to be powered by stellar-mass compact objects accreting at super-Eddington rates. While the discovery of evolutionary cycles have marked a...
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Accretion Properties and Estimation of Spin of Galactic Black Hole Candidate Swift J1728.9-3613 with NuSTAR during its 2019 outburst: Black hole X-ray binaries (BHXRBs) play a crucial role in understanding the accretion of matter onto a black hole. Here, we focus on exploring the transient BHXRB \source~discovered by...
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Dark Matter Density Spikes around Primordial Black Holes: We show that density spikes begin to form from dark matter particles around primordial black holes immediately after their formation at the radiation-dominated cosmological stage. This follows from the fact that in the thermal velocity distribution of particles ...
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Early optical emission in support of synchrotron radiation in $γ$-ray bursts: The origin of prompt emission in $\gamma$-ray bursts (GRBs) is highly debated topic. The observed spectra are supposed to play a crucial role in constraining the location of the emitting region, the strength of the magnetic field and the di...
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A NICER Discovery of a Low-Frequency Quasi-Periodic Oscillation in the Soft-Intermediate State of MAXI J1535-571: We present the discovery of a low-frequency $\approx 5.7$ Hz quasi-periodic oscillation (QPO) feature in observations of the black hole X-ray binary MAXI J1535-571 in its soft-intermediate state, obtained...
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Spectral evolution responsible for the transition from positive lags to negative lags in Gamma-ray Bursts: It was well known that most of gamma-ray bursts (GRBs) are dominated by positive spectral lags, while a small fraction of GRBs show negative lags. However, Wei et al. firstly identified a well-defined transition...
astro-ph_HE
Gravitational-wave Signals From Three-dimensional Supernova Simulations With Different Neutrino-Transport Methods: We compare gravitational-wave (GW) signals from eight three-dimensional simulations of core-collapse supernovae, using two different progenitors with zero-age main sequence masses of 9 and 20 solar masse...
astro-ph_HE