Related papers: Hard X-ray Emission from Cassiopeia A SNR
X-ray emission is one of the signposts of circumstellar interaction in supernovae (SNe), but until now, it has been observed only in core-collapse SNe. The level of thermal X-ray emission is a direct measure of the density of the…
We present the analysis of 21 bright X-ray knots in the Cassiopeia A supernova remnant from observations spanning 10 yr. We performed a comprehensive set of measurements to reveal the kinematic and thermal state of the plasma in each knot,…
X-ray spectra of groups of galaxies, obtained with the GIS instrument onboard ASCA, were investigated for diffuse hard X-rays in excess of the soft thermal emission from their inter-galactic medium (IGM). In total, 18 objects with the IGM…
We report on Chandra X-ray observations of ASASSN-18tb/SN 2018fhw, a low luminosity Type Ia supernova that showed a H line in its optical spectrum. No X-ray emission was detected at the location of the SN. Upper limits to the luminosity of…
We present the results of OSSE observations of the soft gamma ray continuum emission from the Galactic plane at longitude 95 degrees. Emission is detected between 50 and 600 keV where the spectrum is fit well by a power law with photon…
Cas A is a Galactic supernova remnant whose supernova explosion is observed to be of Type IIb from spectroscopy of its light echo. Having its SN type known, observational constraints on the mass-loss history of Cas A's progenitor can…
After the positive detection by BeppoSAX of hard X-ray radiation up to ~80 keV in the Coma cluster spectrum, we present evidence for nonthermal emission from A2256 in excess of thermal emission at a 4.6sigma confidence level. In addition to…
I present the data of the shell of classical Nova Persei (1901) obtained by the Advanced CCD Imaging Spectrometer S3 detector on-board \cha Observatory. The X-ray nebula is affected mostly by the complex interstellar medium around the nova…
We present X-ray spectra of the nucleus of the nearby radio galaxy Centaurus A from observations with the XMM-Newton EPIC CCD cameras (two exposures separated by 12 months) and the Chandra HETGS. For the first time in an FRI type galaxy, we…
Supernova remnants may exhibit both thermal and nonthermal X-ray emission. Such remnants can be distinguished by the weakness of their X-ray lines, because of the presence of a strong nonthermal X-ray continuum. RCW 86 is a remnant with…
Supernova remnants (SNRs) offer the means to study supernovae (SNe) long after the original explosion and can provide a unique insight into the mechanism that governs these energetic events. In this work, we examine the morphologies of…
We found simultaneous decrease of Fe-K line and 4.2-6 keV continuum of Cassiopeia A with the monitoring data taken by Chandra in 2000-2013. The flux change rates in the whole remnant are $-$0.65$\pm$0.02 \% yr$^{-1}$ in the 4.2--6.0 keV…
We investigate the effect of the circumstellar medium density profile on the X-ray emission from outer ejecta knots in the Cassiopeia A supernova remnant using the 1 Ms Chandra observation. The spectra of a number of radial series of ejecta…
We present the hard X-ray (20-100 keV) observations of Cygnus X-1 obtained using a large area balloon-borne Xenon filled Multi-anode Proportional Counter (XMPC) telescope. The observations were carried out during the gamma_2 state of the…
The thermal evolution of young neutron stars (NSs) reflects the neutrino emission properties of their cores. Heinke et al. (2010) measured a 3.6+/-0.6% decay in the surface temperature of the Cassiopeia A (Cas A) NS between 2000 and 2009,…
The Chandra X-ray Observatory recently discovered an X-ray point source near the center of Cassiopeia A, the youngest known Galactic supernova remnant. We have conducted a sensitive search for radio pulsations from this source with the Very…
A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants is employed to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5--100 yr. It is shown that an efficient…
We consider the effect of energy dependent propagation of relativistic electrons in a spatially inhomogeneous medium in order to interpret the broad-band nonthermal radiation of the young supernova remnant (SNR) Cassiopeia A. A two-zone…
We report results of a nine-year monitoring effort on the unusual classical Be with a robotic ground-based (APT) B,V-filtered telescope as well as simultaneous observations in 2004 November with this instrument and the RXTE (X-ray)…
The Crab nebula originated from a core-collapse supernova (SN) explosion observed in 1054 A.D. When viewed as a supernova remnant (SNR), it has an anomalously low observed ejecta mass and kinetic energy for an Fe-core collapse SN. Intensive…