Related papers: Flares from Sgr A* and their emission mechanism
We review our current understanding to the accretion and ejection processes in Sgr A*. Roughly speaking, they correspond to the quiescent and flare states of the source respectively. The high-resolution {\it Chandra} observations to the gas…
The Galactic Center was observed at 8.6 mum in order to detect a mid-infrared (MIR) counterpart of Sgr A*, parallel to NIR observations. The goal was to set constraints on possible emission mechanisms.Imaging data were acquired with the…
Recent near-IR (NIR) and X-ray observations of Sagittarius A*'s spectrum have yielded several strong constraints on the transient energization mechanism, justifying a re-examination of the stochastic acceleration model proposed previously…
We consider the physical implications of the rapid spindown of Soft Gamma Repeater 1900+14, and of the apparent "braking glitch", \Delta P/P = l x 10^-4, that was concurrent with the Aug. 27th giant flare. A radiation-hydrodynamical outflow…
Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) are young neutron stars (NSs) characterized by high X-ray quiescent luminosities, outbursts, and, in the case of SGRs, sporadic giant flares. They are believed to be powered…
The near-IR and X-ray flares in Sagittarius A* are believed to be produced by relativistic electrons via synchrotron and synchrotron self-Comptonization, respectively. These electrons are likely energized by turbulent plasma waves through…
The discovery of a fast radio burst (FRB) associated with a magnetar in the Milky Way by the Canadian Hydrogen Intensity Mapping Experiment FRB collaboration (CHIME/FRB) and the Survey for Transient Astronomical Radio Emission 2 (STARE2)…
Time-resolved spectra of six short gamma-ray bursts (sGRBs), measured by the {\em Swift} telescope, are used to estimate the parameters of a plerion-like model of the X-ray afterglow. The unshrouded, optically thin component of the…
The detection of bright X-ray flares superimposed on the regular afterglow decay in Swift gamma-ray bursts has triggered theoretical speculations on their origin. We study the temporal properties of flares due to internal dissipation and…
We investigate the spectrum of a quasi-monoenergetic ensemble of relativistic electrons, especially for the mildly relativistic case, and discuss the effect of inclination of the magnetic field on the emissivity. We apply the exact…
The Galactic magnetar SGR1935+2154 has been reported to produce the first known example of a bright millisecond duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs), bolstering the association…
Sgr A* is thought to be the radiative manifestation of a ~3.6E6 Msun supermassive black hole at the Galactic center. Its mm/sub-mm spectrum and its flare emission at IR and X-ray wavelengths may be produced within the inner ten…
Compact steady sources of X-ray emission have been detected at the positions of at least two soft gamma-ray repeaters (SGRs). These sources have been interpreted as synchrotron nebulae powered by the neutron star that is causing the bursts.…
Flares from the supermassive black hole in our Galaxy, Sagittarius~A$^\star$ (Sgr A$^\star$), are routinely observed over the last decade or so. Despite numerous observational and theoretical efforts, the nature of such flares still remains…
The blazar S5 0716+714 has been monitored in its flaring state between 2015 January 19 and February 22 with Swift/XRT. During this period an exceptional flux level was observed in the X-ray range as well as in the other wavelengths, e.g.…
Starting in 2013 February, Swift has been performing short daily monitoring observations of the G2 gas cloud near Sgr A* with the X-Ray Telescope to determine whether the cloud interaction leads to an increase in the flux from the Galactic…
Context. The compact radio and near-infrared (NIR) source Sagittarius A* (Sgr A*) associated with the supermassive black hole in the Galactic center was observed at 7 mm in the context of a NIR triggered global Very Long Baseline Array…
We propose a two-temperature radial inflow-outflow model near Sgr A* with self-consistent feeding and conduction. Stellar winds from individual stars are considered to find the rates of mass injection and energy injection. These source…
We present lightcurves obtained in X-ray by the XMM-Newton EPIC cameras and simultaneous radio lightcurves obtained with the VLA for five active M-type flare stars. A number of flare events were observed, and by comparing radio with X-ray…
We present one possible mechanism for the giant flares of the Soft Gamma-Ray Repeaters (SGRs) within the framework of magnetar, i.e., superstrongly magnetized neutron star model, motivated by the positive period increase associated with the…