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Phase shift of gravitational waves induced by aberration: The velocity of a gravitational wave (GW) source provides crucial information about its formation and evolution processes. Previous studies considered the Doppler effect on the phase of GWs as a potential signature of a time-dependent velocity of the source. How...
astro-ph_HE
Early Spectral Evolution of the Rapidly Expanding Type Ia SN 2006X: We present optical spectroscopic and photometric observations of Type Ia supernova (SN) 2006X from --10 to +91 days after the $B$-band maximum. This SN exhibits one of the highest expansion velocity ever published for SNe Ia. At premaximum phases, the ...
astro-ph_HE
Constraining Low-luminosity Gamma-Ray Bursts as Ultra-high-energy Cosmic Ray Sources Using GRB 060218 as a Proxy: We study the connection between low-luminosity gamma-ray bursts (llGRBs) and ultra-high-energy cosmic rays (UHECRs) using the canonical low-luminosity GRB 060218 as a proxy. We focus on the consequential ...
astro-ph_HE
Megaparsec-scale Radio Structure Associated with a Hybrid Blazar SBS B1646+499: Episodic Jet Activity with Precessing Axis: Here we report on the total-intensity 610 MHz GMRT observations of the peculiar hybrid blazar SBS B1646+499, which merges the properties of BL Lacertae objects and flat-spectrum radio quasars. T...
astro-ph_HE
On the nature of the 'hostless' short GRBs: A significant proportion ($\sim30\%$) of the short-duration gamma-ray bursts (SGRBs) localised by Swift have no detected host galaxy coincident with the burst location to deep limits, and also no high-likelihood association with proximate galaxies on the sky. These SGRBs may ...
astro-ph_HE
Hints of a second explosion (a quark nova) in Cassiopeia A Supernova: We show that the explosive transition of the neutron star (NS) to a quark star (QS) (a Quark Nova) in Cassiopeia A (Cas A) a few days following the SN proper can account for several of the puzzling kinematic and nucleosynthetic features observed. The...
astro-ph_HE
A Study of the Long-term Spectral Variations of 3C 66A Observed with the Fermi and Kanata Telescopes: 3C 66A is an intermediate-frequency-peaked BL Lac object detected by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. We present a study of the long-term variations of this blazar seen over 2 y...
astro-ph_HE
Searching for Dark Matter Annihilation in M87: Clusters of galaxies, such as the Virgo cluster, host enormous quantities of dark matter, making them prime targets for efforts in indirect dark matter detection via potential radiative signatures from annihilation of dark matter particles and subsequent radiative losses o...
astro-ph_HE
Calibrating X-ray binary luminosity functions via optical reconnaissance II. The high-mass XLF and globular cluster population of X-ray binaries in the low star-forming spiral M81: We characterize the optical counterparts to the compact X-ray source population within the nearby spiral galaxy M81 using multi-band Hu...
astro-ph_HE
Cosmic searches for Lorentz invariance violation: Cosmic messengers (gamma rays, cosmic rays, neutrinos and gravitational waves) provide a powerful complementary way to search for Lorentz invariance violating effects to laboratory-based experiments. The long baselines and high energies involved make Cherenkov telescope...
astro-ph_HE
A variable ULX and possible IMBH candidate in M51a: ULX-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ultraluminous X-ray source, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We analyse the source using arch...
astro-ph_HE
The Mergers in Abell 2256: Displaced Gas and its Connection to the Radio-emitting Plasma: We present the results of deep Chandra and XMM-Newton X-ray imaging and spatially-resolved spectroscopy of Abell 2256, a nearby (z=0.058) galaxy cluster experiencing multiple mergers and displaying a rich radio morphology domina...
astro-ph_HE
The polarization of the boundary layer around weakly magnetized neutron stars in X-ray binaries: X-ray binaries hosting a compact object have been among the main targets of the Imaging X-ray Polarimetry Explorer (IXPE) since its launch, due to their high brightness in the 2-8 keV energy band. The spectropolarimetric ...
astro-ph_HE
Status And Highlights Of VERITAS: VERITAS (Very Energetic Radiation Imaging Telescope Array System) is an array of atmospheric Cherenkov telescopes sensitive to very high energy (VHE) gamma-rays above 100 GeV. Located at the Fred Lawrence Whipple Observatory in southern Arizona, USA, the VERITAS array of four 12m-diame...
astro-ph_HE
Importance of resolving the spectral support of beam-plasma instabilities in simulations: Many astrophysical plasmas are prone to beam-plasma instabilities. For relativistic and dilute beams, the {\it spectral} support of the beam-plasma instabilities is narrow, i.e., the linearly unstable modes that grow with rates ...
astro-ph_HE
Search for Decaying Dark Matter in the Virgo Cluster of Galaxies with HAWC: The decay or annihilation of dark matter particles may produce a steady flux of very-high-energy gamma rays detectable above the diffuse background. Nearby clusters of galaxies provide excellent targets to search for the signatures of particl...
astro-ph_HE
Hints of the jet composition in gamma-ray bursts from dissipative photosphere models: We present a model for gamma-ray bursts where a dissipative photosphere provides the usual spectral peak around MeV energies accompanied by a subdominant thermal component. We treat the initial acceleration of the jet in a general w...
astro-ph_HE
Indirect dark matter search in the Galactic Centre with IceCube: It is assumed that dark matter can annihilate or decay into Standard Model particles which then can produce a neutrino flux detectable at IceCube. Such a signal can be emitted from the Galactic Center thanks to the high density of dark matter abundance be...
astro-ph_HE
The interstellar environment in the outer Galaxy as seen in gamma rays by Fermi: Gamma-ray emission produced by interactions between cosmic rays (CRs) and interstellar gas traces the product of their densities throughout the Milky Way. The outer Galaxy is a privileged target of investigation to separate interstellar ...
astro-ph_HE
Blueshifted absorption lines from X-ray reflection in IRAS 13224-3809: We explore a disc origin for the highly-blueshifted, variable absorption lines seen in the X-ray spectrum of the Narrow Line Seyfert 1 galaxy IRAS13224-3809. The blueshift corresponds to a velocity of about 0.25c. Such features in other Active Galac...
astro-ph_HE
Lorentz Factor-Isotropic Luminosity/Energy Correlations of GRBS and Their Interpretation: The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (Gamma_0) is a key parameter to understand the GRB physics. Liang et al. have discovered a correlation between Gamma_0 and isotropic gamma-ray energy: Gamma_0\proptoE_{...
astro-ph_HE
Waves in pulsar winds: The radio, optical, X-ray and gamma-ray nebulae that surround many pulsars are thought to arise from synchrotron and inverse Compton emission. The energy powering this emission, as well as the magnetic fields and relativistic particles, are supplied by a "wind" driven by the central object. The i...
astro-ph_HE
Ultra High Energy Neutrinos: Absorption, Thermal Effects and Signatures: We study absorption of ultra high energy neutrinos by the cosmic neutrino background, with full inclusion of the effect of the thermal distribution of the background on the resonant annihilation channel. For a hierarchical neutrino mass spectrum (...
astro-ph_HE
A Photosphere-Internal Shock Model of Gamma-Ray Bursts: Case Studies of Fermi/LAT Bursts: Radially inhomogeneous gamma-ray burst (GRB) jets release variable photospheric emission and can have internal shocks occurring above the photosphere. We generically formulate a photospheric emission model of GRBs including Comp...
astro-ph_HE
Equations of state in the Hartle-Thorne model of neutron stars selecting acceptable variants of the resonant switch model of twin HF QPOs in the atoll source 4U 1636-53: The Resonant Switch (RS) model of twin high-frequency quasi-periodic oscillations (HF QPOs) observed in neutron star binary systems, based on swit...
astro-ph_HE
The XMM-Newton survey of the Small Magellanic Cloud: Although numerous archival XMM-Newton observations existed towards the Small Magellanic Cloud (SMC) before 2009, only a fraction of the whole galaxy was covered. Between May 2009 and March 2010 we carried out an XMM-Newton survey of the SMC, in order to obtain a comp...
astro-ph_HE
The destruction and recreation of the X-ray corona in a changing-look Active Galactic Nucleus: We present the drastic transformation of the X-ray properties of the active galactic nucleus 1ES 1927+654, following a changing-look event. After the optical/UV outburst the power-law component, produced in the X-ray corona...
astro-ph_HE
Lorentz invariance violation from GRB221009A: The Large High Altitude Air Shower Observatory~(LHAASO) reported observation of photons with energies above 10~TeV from gamma ray burst GRB221009A. A suggestion was proposed that this result may contradict with our knowledge of special relativity~(SR) and the standard model...
astro-ph_HE
In-medium enhancement of the modified Urca neutrino reaction rates: We calculate modified Urca neutrino emission rates in the dense nuclear matter in neutron star cores. We find that these rates are strongly enhanced in the beta-stable matter in regions of the core close to the direct Urca process threshold. This enhan...
astro-ph_HE
Revealing the variation mechanism of ON 231 via the two-components shock-in-jet model: The variation mechanism of blazars is a long-standing unresolved problem. In this work, we present a scenario to explain diverse variation phenomena for ON 231, where the jet emissions are composed of the flaring and the less varia...
astro-ph_HE
Exact analytical expression for the synchrotron radiation spectrum in the Gaussian turbulent magnetic field: We demonstrate that the exact solution for the spectrum of synchrotron radiation from an isotropic population of mono-energetic electrons in turbulent magnetic field with Gaussian distribution of local field s...
astro-ph_HE
Magnetically Confined Mountains on Accreting Neutron Stars in General Relativity: The general relativistic formulation of the problem of magnetically confined mountains on neutron stars is presented, and the resulting equations are solved numerically, generalising previous Newtonian calculations. The hydromagnetic st...
astro-ph_HE
Very high energy gamma-ray follow-up observations of novae and dwarf novae with the MAGIC telescopes: In the last few years the Fermi-LAT instrument has detected GeV gamma-ray emission from several novae. Such GeV emission can be interpreted in terms of inverse Compton emission from electrons accelerated in the shock...
astro-ph_HE
Test of the string loop oscillation model using kHz quasiperiodic oscillations in a neutron star binary: The model of current-carrying string loop oscillations is tested to explain the special set of frequencies related to the high-frequency quasiperiodic oscillations (HF QPOs) observed recently in the low-mass X-ray...
astro-ph_HE
SN 2019zrk, a bright SN 2009ip analog with a precursor: We present photometric and spectroscopic observations of the Type IIn supernova SN 2019zrk (also known as ZTF20aacbyec). The SN shows a $\gtrsim$ 100 day precursor, with a slow rise, followed by a rapid rise to M $\sim -19.2$ in the $r$ and $g$ bands. The post-pea...
astro-ph_HE
NuSTAR Hard X-ray Survey of the Galactic Center Region I: Hard X-ray Morphology and Spectroscopy of the Diffuse Emission: We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecul...
astro-ph_HE
No evidence for a low-mass black hole in Swift J1753.5-0127: We present high-resolution, time-resolved optical spectroscopy of the black hole X-ray transient Swift J1753.5-0127. Our optical spectra do not show features that we can associate with the companion star. However we do observe broad, double-peaked emission li...
astro-ph_HE
Variable mass accretion and failed wind explain changing look phenomena in NGC 1365: Changing look active galactic nuclei (CLAGNs) show complex nature in their X-ray spectral shape and line of sight column density variation. The physical mechanisms responsible for these variations are unclear. Here, we study the spec...
astro-ph_HE
Probing dark matter annihilation in the Galaxy with antiprotons and gamma rays: A possible hint of dark matter annihilation has been found in Cuoco, Korsmeier and Kr\"amer (2017) from an analysis of recent cosmic-ray antiproton data from AMS-02 and taking into account cosmic-ray propagation uncertainties by fitting a...
astro-ph_HE
High-energy neutrinos from Galactic sources: Even 100 years after the discovery of cosmic rays their origin remains a mystery. In recent years, TeV gamma-ray detectors have discovered and investigated many Galactic sources where particles are accelerated up to energies of 100 TeV. However, it has not been possible up t...
astro-ph_HE
Update on the GRB universal scaling E$_{\rm{X,iso}}$-E$_{\rm{γ,iso}}$-E$_{\rm{pk}}$ with ten years of $Swift$ data: From a comprehensive statistical analysis of $Swift$ X-ray light-curves of gamma-ray bursts (GRBs) collected from December 2004 to the end of 2010, we found a three-parameter correlation between the i...
astro-ph_HE
Modelling of blazar SEDs with the nonlinear SSC cooling process: Observations of blazar flaring states reveal remarkably different variability time scales. Especially rapid flares with flux doubling time scales of the order of minutes have been puzzling for quite some time. Many modeling attempts use the well known lin...
astro-ph_HE
The Soft State of the Black Hole Transient Source MAXI J1820+070: Emission from the Edge of the Plunge Region?: The Galactic black hole X-ray binary MAXI J1820+070 had a bright outburst in 2018 when it became the second brightest X-ray source in the Sky. It was too bright for X-ray CCD instruments such as XMM-Newton ...
astro-ph_HE
New Measurement of Muon Neutrino Disappearance from the IceCube Experiment: The IceCube Neutrino Observatory is a Cherenkov detector located at the South Pole. Its main component consists of an in-ice array of optical modules instrumenting one cubic kilometer of deep Glacial ice. The DeepCore sub-detector is a denser...
astro-ph_HE
The Origin of the Prompt Emission for Short GRB 170817A: Photosphere Emission or Synchrotron Emission?: The first gravitational-wave event from the merger of a binary neutron star system (GW170817) was detected recently. The associated short gamma-ray burst (GRB 170817A) has a low isotropic luminosity ($\sim 10^{47}$...
astro-ph_HE
First search for GeV neutrinos from bright gamma-ray solar flares using the IceCube Neutrino Observatory: In response to a reported increase in the total neutrino flux in the Homestake experiment in coincidence with solar flares at the end of the eighties, solar neutrino detectors have searched for solar flare signal...
astro-ph_HE
SN 2023emq: a flash-ionised Ibn supernova with possible CIII emissio: SN 2023emq is a fast-evolving transient initially classified as a rare Type Icn supernova (SN), interacting with a H- and He-free circumstellar medium (CSM) around maximum light. Subsequent spectroscopy revealed the unambiguous emergence of narrow He...
astro-ph_HE
Testing the rotating hot spot model using X-ray burst oscillations from 4U 1636-536: Precise and accurate measurements of neutron star masses and radii would provide valuable information about the still uncertain properties of cold matter at supranuclear densities. One promising approach to making such measurements i...
astro-ph_HE
Supernova remnants in the very-high-energy sky: prospects for the Cherenkov Telescope Array: The Cherenkov Telescope Array is expected to lead to the detection of many new supernova remnants in the TeV and multi-TeV range. In addition to the individual study of each SNR, the study of these objects as a population can...
astro-ph_HE
Neutron stars as sources of gravitational waves: The global network of ground-based gravitational-wave detectors (the Advanced LIGO and the Advanced Virgo) is sensitive at the frequency range corresponding to relativistic stellar-mass compact objects. Among the promising types of gravitational-wave sources are binary s...
astro-ph_HE
Gamma-ray burst spectra and spectral correlations from sub-photospheric Comptonization: One of the most important unresolved issues in gamma-ray burst physics is the origin of the prompt gamma-ray spectrum. Its general non-thermal character and the softness in the X-ray band remain unexplained. We tackle these issues...
astro-ph_HE
Search for fingerprints of disoriented chiral condensates in cosmic ray showers: Although the generation of disoriented chiral condensates (DCCs), where the order parameter for chiral symmetry breaking is misaligned with respect to the vacuum direction in isospin state, is quite natural in the theory of strong intera...
astro-ph_HE
Astrophysical signatures of leptonium: More than 10^43 positrons annihilate every second in the centre of our Galaxy yet, despite four decades of observations, their origin is still unknown. Many candidates have been proposed, such as supernovae and low mass X-ray binaries. However, these models are difficult to reconc...
astro-ph_HE
Study of Asymptotic Velocity in the Bondi-Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein-Gauss-Bonnet Gravities: Understanding the physical structures of the accreated matter very close to the black hole in quasars and active galactic nucleus (AGNs) is an important milestone to constrain the activities ...
astro-ph_HE
Neutrino cooling and spin-down of rapidly rotating compact stars: The gravitational-wave instability of r-modes in rapidly rotating compact stars is believed to spin them down to angular frequencies of about a tenth of the Kepler frequency soon after their birth in a Supernova. We point out that the r-mode perturbation...
astro-ph_HE
Efficiency of Thin Magnetically-Arrested Disks Around Black Holes: The radiative and jet efficiencies of thin magnetized accretion disks around black holes (BHs) are affected by BH spin and the presence of a magnetic field that, when strong, could lead to large deviations from Novikov-Thorne (NT) thin disk theory. To s...
astro-ph_HE
Radio and X-ray observations of Five TeV SNRs: We briefly summarize recent results of five TeV SNRs from radio and X-ray observations. We focus on remeasuring kinematic distances of 5 TeV SNRs, i.e. HESS J1732-347/SNR G353.6-0.7 (3.2 kpc), HESS J1834-087/G23.3-0.3 (also W41, 4.0 kpc), HESS J1833-105/G21.5-0.9 (4.8 kpc)...
astro-ph_HE
Evidence for quark-matter cores in massive neutron stars: The theory governing the strong nuclear force, Quantum Chromodynamics, predicts that at sufficiently high energy densities hadronic nuclear matter undergoes a deconfinement transition to a new phase of quarks and gluons. Although this has been observed in ultrar...
astro-ph_HE
The Correlation between Dispersion Measure and X-ray Column Density from Radio Pulsars: Pulsars are remarkable objects that emit across the entire electromagnetic spectrum, providing a powerful probe of the interstellar medium. In this study, we investigate the relation between dispersion measure (DM) and X-ray absor...
astro-ph_HE
On the simultaneous generation of radio and soft X-ray emission by AXP 4U 0142+61: In the present paper we study the possibility of a simultaneous generation of radio waves and soft $X$-rays by means of the quasi-linear diffusion (QLD) in the anomalous pulsar AXP 4U 0142+61. Considering the magnetosphere composed of ...
astro-ph_HE
GN-z11-flash in the context of Gamma-Ray Burst Afterglows: The recently discovered rapid transient GN-z11-flash has been suggested to be the prompt-emission ultraviolet flash associated with a gamma-ray burst serendipitously exploding in the ultra-high-$z$ galaxy GN-z11. We here place the flash into the context of the ...
astro-ph_HE
Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and $γ$-ray brightness levels: In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and $\gamma$-ray bands. We present optical photometric and pol...
astro-ph_HE
Swift: the science across the rainbow. Mission Overview and Highlights of Results: I present an overview of the Swift mission, which was launched on November 20, 2004 to discover and observe the most energetic of astrophysical phenomena, gamma-ray bursts (GRBs). After almost 6 years in space the Observatory is in exc...
astro-ph_HE
Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft State Observed with Suzaku: We present observations of a transient He-like Fe K alpha absorption line in Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near superior conjunction during the high/soft state, which enable us ...
astro-ph_HE
Broad band polarimetric follow-up of Type IIP SN 2012aw: We present the results based on R-band polarimetric follow-up observations of the nearby (~10 Mpc) Type II-plateau SN 2012aw. Starting from ~10 days after the SN explosion, these polarimetric observations cover ~90 days (during the plateau phase) and are distribu...
astro-ph_HE
Astrophysical Implications of the Binary Black-Hole Merger GW150914: The discovery of the gravitational-wave source GW150914 with the Advanced LIGO detectors provides the first observational evidence for the existence of binary black-hole systems that inspiral and merge within the age of the Universe. Such black-hole m...
astro-ph_HE
Massive protostars as gamma-ray sources: Massive protostars have associated bipolar outflows with velocities of hundreds of km s$^{-1}$. Such outflows can produce strong shocks when interact with the ambient medium leading to regions of non-thermal radio emission. We aim at exploring under which conditions relativistic...
astro-ph_HE
Impact of Massive Binary Star and Cosmic Evolution on Gravitational Wave Observations II: Double Compact Object Rates and Properties: Making the most of the rapidly increasing population of gravitational-wave detections of black hole (BH) and neutron star (NS) mergers requires comparing observations with population s...
astro-ph_HE
Reverse Shock Emission Driven By Post-Merger Millisecond Magnetar Winds: Effects of the Magnetization Parameter: The study of short-duration gamma-ray bursts provides growing evidence that a good fraction of double neutron star mergers lead to the formation of stable millisecond magnetars. The launch of Poynting flux...
astro-ph_HE
Connections Between Local and Global Turbulence in Accretion Disks: We analyze a suite of global magnetohydrodynamic (MHD) accretion disk simulations in order to determine whether scaling laws for turbulence driven by the magnetorotational instability, discovered via local shearing box studies, are globally robust. The...
astro-ph_HE
Dynamical Modeling of CXOGBS J175553.2-281633: A 10 Hour Long Orbital Period Cataclysmic Variable: We present modeling of the long-term optical light curve and radial velocity curve of the binary stellar system CXOGBS J175553.2-281633, first detected in X-rays in the \textit{Chandra} Galactic Bulge Survey. We analyze...
astro-ph_HE
Interesting Clues to Detect Hidden Tidal Disruption Events in Active Galactic Nuclei: In the manuscript, effects of Tidal Disruption Events (TDEs) are estimated on long-term AGN variability, to provide interesting clues to detect probable hidden TDEs in normal broad line AGN with apparent intrinsic variability which ...
astro-ph_HE
Gamma Ray Burst Prompt correlations: The mechanism responsible for the prompt emission of gamma-ray bursts (GRBs) is still a debated issue. The prompt phase-related GRB correlations can allow to discriminate among the most plausible theoretical models explaining this emission. We present an overview of the observationa...
astro-ph_HE
Compact Object Modeling in the Globular Cluster 47 Tucanae: The globular cluster 47~Tucanae (47~Tuc) is one of the most massive star clusters in the Milky Way and is exceptionally rich in exotic stellar populations. For several decades it has been a favorite target of observers, and yet it is computationally very chall...
astro-ph_HE
Neutron stars - thermal emitters: Confronting theoretical models with observations of thermal radiation emitted by neutron stars is one of the most important ways to understand the properties of both, superdense matter in the interiors of the neutron stars and dense magnetized plasmas in their outer layers. Here we rev...
astro-ph_HE
Approximating new ice models with B-splines for improved IceCube event reconstruction: application to cascades and tracks: Event signatures in IceCube are complex, modulated by both particle physics and properties of the ice and detector. Event reconstruction thus requires accurate modeling of ice properties and dete...
astro-ph_HE
Inferring spin tilts at formation from gravitational wave observations of binary black holes: Interfacing precession-averaged and orbit-averaged spin evolution: Two important parameters inferred from the gravitational wave signals of binaries of precessing black holes are the spin tilt angles, i.e., the angles at w...
astro-ph_HE
Discovery of a 26.2 day period in the long-term X-ray light curve of SXP 1323: a very short orbital period for a long spin period pulsar: Context. About 120 Be/X-ray binaries (BeXBs) are known in the Small Magellanic Cloud (SMC); about half of them are pulsating with periods from a few to hundreds of seconds. SXP 132...
astro-ph_HE
Magnetic Deflections of Ultra-High Energy Cosmic Rays from Centaurus A: We present the results of a study that simulates trajectories of ultra-high energy cosmic rays from Centaurus A to Earth, for particle rigidities from $E/Z = 2$ EV to 100 EV, i.e., covering the possibility of primary particles as heavy as Fe nuclei...
astro-ph_HE
The pulsar synchrotron: coherent radio emission: We propose a simple physical picture for the generation of coherent radio emission in the axisymmetric pulsar magnetosphere that is quite different from the canonical paradigm of radio emission coming from the magnetic polar caps. In this first paper we consider only the...
astro-ph_HE
GRB 090510: a short burst from a massive star ?: GRB afterglow 090510 is (so far) the best-monitored afterglow in the optical, X-ray, and above 100 MeV, measurements covering 2-3 decades in time at each frequency. Owing to its power-law temporal decay and power-law spectrum, it seems very likely that the highest energy...
astro-ph_HE
A joint spectro-imaging analysis of the XMM-Newton and HESS observations of the supernova remnant RX J1713.7-3946: The supernova remnant (SNR) RX J1713.7-3946 (also known as G347.3-0.5) is part of the class of remnants dominated by synchrotron emission in X-rays. It is also one of the few shell-type SNRs observed at ...
astro-ph_HE
Spectral and morphological analysis of the remnant of Supernova 1987A with ALMA & ATCA: We present a comprehensive spectral and morphological analysis of the remnant of Supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal a...
astro-ph_HE
Gravitational wave astronomy of single sources with a pulsar timing array: Abbreviated: We investigate the potential of detecting the gravitational wave from individual binary black hole systems using pulsar timing arrays (PTAs) and calculate the accuracy for determining the GW properties. This is done in a consist...
astro-ph_HE
Optical and Radio Variability of the Blazar S4 0954+658: We present an optical-to-radio study of the BL Lac object S4 0954+658 observations during 1998-2023. The measurements were obtained with the SAO RAS Zeiss-1000 1-m and AS-500/2 0.5-m telescopes in 2003-2023, with the RATAN-600 radio telescope at 1.25 (0.96, 1.1),...
astro-ph_HE
Discovery of the Optical Counterparts to Four Energetic Fermi Millisecond Pulsars: In the last few years, over 43 millisecond radio pulsars have been discovered by targeted searches of unidentified gamma-ray sources found by the Fermi Gamma-Ray Space Telescope. A large fraction of these millisecond pulsars are in com...
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Search for Gravitational Waves Associated with Fast Radio Bursts Detected by CHIME/FRB During the LIGO--Virgo Observing Run O3a: We search for gravitational-wave transients associated with fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project (CHIME/FRB), dur...
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The nova-like nebular optical spectrum of V404 Cygni at the beginning of the 2015 outburst decay: We report on FORS2 optical spectroscopy of the black hole X-ray binary V404 Cygni, performed at the very beginning of its 2015 outburst decay, complemented by quasi-simultaneous $Swift$ X-ray and ultra-violet as well as ...
astro-ph_HE
Time-dependent neutrino emission from Mrk 421 during flares and predictions for IceCube: Blazars are prime candidate sources for the high energy neutrinos recently detected by IceCube. Being one of the brightest sources in the extragalactic X-ray and $\gamma$-ray sky as well as one of the nearest blazars to Earth, Mr...
astro-ph_HE
QPO-jet relation in X-ray binaries: In the past years, a clear picture of the evolution of outbursts of black-hole X-ray binaries has emerged. While the X-ray properties can be classified into our distinct states, based on spectral and timing properties, the observations in the radio band have shown strong links betwee...
astro-ph_HE
Detection of diffuse gamma-ray emission near the young massive cluster NGC 3603: We report the Fermi Large Area Telescope's detection of extended gamma-ray emission towards the direction of the young massive star cluster NGC 3603. The emission shows a hard spectrum with a photon index of 2.3 from 1 GeV to 250 GeV. Th...
astro-ph_HE
Insight-HXMT, NuSTAR and INTEGRAL Data Show Disk Truncation in the Hard State of the Black-Hole X-Ray Binary MAXI J1820+070: We study X-ray and soft gamma-ray spectra from the hard state of the accreting black-hole binary MAXI J1820+070. We perform analysis of joint spectra from HXMT, NuSTAR and INTEGRAL. We find an ...
astro-ph_HE
Constraining cosmic-ray acceleration in the magnetospheric gaps of Sgr A*: Sagittarius A* (Sgr A*) is a potential VHE gamma-ray and cosmic-ray source. We examine limits to gap-type particle acceleration in the magnetosphere of Sgr A*, showing that in the current phase of activity proton acceleration to PeV energies i...
astro-ph_HE
Is the energy generation rate of nuclear reactions in hot accretion flows important?: The temperature of hot accretion flows around black holes is sufficiently high for the ignition of nuclear reactions. This is potentially an important nucleosynthesis mechanism in the universe. As the first step in studying this pro...
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High-energy electromagnetic offline follow-up of LIGO-Virgo gravitational-wave binary coalescence candidate events: We present two different search methods for electromagnetic counterparts to gravitational-wave (GW) events from ground-based detectors using archival NASA high-energy data from the Fermi-GBM and RXTE-AS...
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The power-law component of the X-ray emissions from pulsar wind nebulae and their pulsars: To look for possible phenomenological connections between pulsar's timing properties and emissions from pulsar wind nebulae and their pulsars, we studied the power-law component of the X-ray emissions from 35 pulsar wind nebula...
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Evidence for a change in the radiation mechanism in the hard state of GRO J1655-40. Hysteresis in the broad-band noise components: We have analysed RXTE archival data to study the aperiodic variability of the black-hole binary GRO J1655-40 during the hard state of the 2005 outburst. We computed the 0.008-64 Hz power ...
astro-ph_HE
Constraints on the X-ray Luminosity Function of AGN at z=5.7-6.4 with the Extragalactic Serendipitous Swift Survey: X-ray luminosity functions (XLFs) of Active Galactic Nuclei (AGN) trace the growth and evolution of supermassive black hole populations across cosmic time, however, current XLF models are poorly constra...
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A Luminous Gamma-ray Binary in the Large Magellanic Cloud: Gamma-ray binaries consist of a neutron star or a black hole interacting with a normal star to produce gamma-ray emission that dominates the radiative output of the system. Only a handful of such systems have been previously discovered, all within our Galaxy. H...
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Search for transitions between states in redbacks and black widows using seven years of Fermi-LAT observations: Considering about seven years of Fermi-Large Area Telescope (LAT) data, we present a systematic search for variability possibly related to transitions between states in redbacks and black widow systems. Tra...
astro-ph_HE