Related papers: Flares from Sgr A* and their emission mechanism
Sagittarius A* harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A* spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to…
Despite advances in our understanding of low luminosity active galactic nuclei (LLAGNs), the fundamental details about the mechanisms of radiation and flare/outburst in hot accretion flow are still largely missing. We have systematically…
We consider the synchrotron emission from relativistic shocks assuming that the radiating electrons cool rapidly (either through synchrotron or any other radiation mechanism). It is shown that the theory of synchrotron emission in the fast…
We discuss here constraints on the particle acceleration models from the observed gamma-ray bursts spectra. The standard synchrotron shock model assumes that some fraction of available energy is given instantaneously to the electrons which…
While the non-thermal radio through at least near-infrared emission in the hard state in X-ray binaries (XRBs) is known to originate in jets, the source of the non-thermal X-ray component is still uncertain. We introduce a new model for…
We calculate the synchrotron self-Compton emission from internal shocks occurring in relativistic winds as a source of gamma-ray bursts, with allowance for self-absorption. For plausible model parameters most pulses within a Gamma-Ray Burst…
Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short…
At the end of March 2004, the blazar S5 0716+714 underwent an optical outburst that prompted for quasi-simultaneous target-of-opportunity observations with the INTEGRAL and XMM-Newton satellites. In this paper, we report the results of the…
(ABBREVIATED) We consider the structure of neutron star magnetospheres threaded by large-scale electrical currents, and the effect of resonant Compton scattering by the charge carriers (both electrons and ions) on the emergent X-ray spectra…
We present radio continuum light curves of the magnetar SGR J1745$-$2900 and Sgr A* obtained with multi-frequency, multi-epoch Very Large Array observations between 2012 and 2014. During this period, a powerful X-ray outburst from SGR…
Recently, in a few case studies we demonstrated that gyrosynchrotron microwave emission can be detected directly from the acceleration region when the trapped electron component is insignificant. For the statistical study reported here, we…
This work reports the first discovery of (negative) spectral lags in the X-ray emission below 10 keV from the gamma ray binary $LSI +61^{o} $ 303 during large flaring episodes using the Rossi X-ray Timing Explorer (RXTE) observations. It is…
X-ray flares have routinely been observed from the supermassive black hole, Sagittarius A$^\star$ (Sgr A$^\star$), at our Galactic center. The nature of these flares remains largely unclear, despite of many theoretical models. In this…
In this article we summarise and discuss the infrared, radio, and X-ray emission from the supermassive black hole in the Galactic Centre, SgrA*. We include new results from near-infrared polarimetric imaging observations obtained on May…
Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with…
The recent detection of variable infrared emission from Sagittarius A*, combined with its previously observed flare activity in X-rays, provides compelling evidence that at least a portion of this object's emission is produced by nonthermal…
We present high-resolution multiwavelength radio continuum images of the region within 150$"$ of Sgr A*, revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2" east-west ridge of…
Monitoring of Sagittarius A* from X-ray to radio wavelengths has revealed structured variability --- including X-ray flares --- but it is challenging to establish correlations between them. Most studies have focused on variability in the…
We present the results of Chandra, RXTE, and VLA observations of SGR 1900+14 in the immediate aftermath of its 2001 April 18 giant flare event. In the X-ray band we find the source in a pulsating and bursting state, with time-averaged 2--10…
The analysis of narrowband drifting of type III-like structures in radio bursts dynamic spectra allows to obtain unique information about primary energy release mechanisms in solar flares. The SSRT spatially resolved images and a high…