Related papers: X-ray flares in GRBs: general considerations and p…
Swift-XRT observations of the X-ray emission from gamma ray bursts (GRBs) and during the GRB afterglow have led to many new results during the past two years. One of these exciting results is that approximately 1/3-1/2 of GRBs contain…
The X-ray light curves of gamma-ray bursts (GRBs) display complex features, including plateaus and flares, that challenge theoretical models. Here, we study the properties of flares that are observed in the early afterglow phase (up to a…
We propose that gamma ray bursts (GRBs) are produced by a shower of heavy blobs running into circumstellar material at highly relativistic speeds. The gamma ray emission is produced in the shocks these bullets drive into the surrounding…
The many similarities between the prompt emission pulses in gamma ray bursts (GRBs) and X-ray flares during the fast decay and afterglow phases of GRBs suggest a common origin. In the cannonball (CB) model of GRBs, this common origin is…
We present time-resolved spectral analysis of the steep decay segments of 29 bright X-ray flares of gamma-ray bursts (GRBs) observed with the Swift/X-ray telescope, and model their lightcurves and spectral index evolution behaviors with the…
Gamma-ray bursts (GRBs) are a mixed class of sources consisting of, at least, the long duration and short-hard subclasses, the X-ray flashes, and the low-luminosity GRBs. In all cases, the release of enormous amounts of energy on a short…
We present an updated catalog of 113 X-ray flares detected by Swift in the ~33% of the X-ray afterglows of Gamma-Ray Bursts (GRB). 43 flares have a measured redshift. For the first time the analysis is performed in 4 different X-ray energy…
X-ray flares are generally supposed to be produced by the later central engine activities, and may share the similar physical origin with prompt emission of gamma-ray bursts (GRBs). In this paper, we have analyzed all significant X-ray…
Gamma-ray burst X-ray flares are believed to mark the late time activity of the central engine. We compute the temporal evolution of the average flare luminosity $< L >$ in the common rest frame energy band of 44 GRBs taken from the large…
The prompt emission of Gamma Ray Bursts extends from the early pulses observed in gamma-rays (>15 keV) to very late flares of X-ray photons (0.3-10 keV). The duration of prompt gamma-ray pulses is rather constant while the width of X-ray…
We develop a model to explain the flaring activity in gamma-ray burst X-ray afterglows within the framework of slightly misaligned observers to structured jets. We suggest that flares could be the manifestation of prompt dissipation within…
The flare activity that is observed in GRBs soon after the prompt emission with the XRT (0.3-10 KeV) instrument on board of the Swift satellite is leading to important clues in relation to the physical characteristics of the mechanism…
We consider the properties of a hyperaccretion model for gamma-ray bursts (GRBs) at the late time when the mass supply rate is expected to decrease with time. We point out that the region in the vicinity of the accretor and the accretor…
One of the major achievements of Swift is the discovery of the erratic X-ray flares harboring nearly half of gamma-ray bursts (GRBs), both for long-duration and short-duration categories, and both for traditional hard GRBs and soft X-ray…
We discuss the origin of X-Ray Flashes (XRFs), a recently discovered class of Gamma-Ray Bursts (GRBs). Using a simplified model for internal shocks we check if XRFs can be intrinsically soft due to some specific values of the parameters…
X-ray flares, lasting for $\sim 100 - 1000$ s in the X-ray band, are often observed following gamma-ray bursts (GRBs). The physical origin of X-ray flares is still unknown merely with the temporal/spectral information. On the other hand,…
Simultaneous Swift and Fermi observations of gamma-ray bursts (GRBs) offer a unique broadband view of their afterglow emission, spanning more than ten decades in energy. We present the sample of X-ray flares observed by both Swift and Fermi…
X-ray flares were discovered in the afterglow phase of gamma-ray bursts (GRBs) by the {\em Swift} satellite a decade ago and known as a canonical component in GRB X-ray afterglows. In this paper, we constrain the Lorentz factors of GRB…
The gamma-ray emission of blazar jets shows a pronounced variability and this feature provides limits to the size and to the speed of the emitting region. We study the gamma-ray variability of bright blazars using data from the first 18…
X-ray flares of gamma-ray bursts (GRBs) are usually observed in the soft X-ray range and the spectral coverage is limited. In this paper, we present an analysis of 32 GRB X-ray flares that are simultaneously observed by both BAT and XRT on…