Related papers: The three-parameter correlations about optical pla…
We compile 23 Gamma-ray Bursts (GRBs) and 21 blazars with estimated Doppler factors, and the Doppler factors of GRBs are estimated from their Lorentz factors by assuming their jet viewing angles \theta->0 degree. Using the conventional…
Using data mostly assembled by previous authors, we consider the linear correlation between the apparent radiative efficiency $\epsilon_{\gamma}$ (defined as the ratio of isotropic equivalent radiative output to inferred isotropic…
We present a photometric study of the optical counterpart of the long-duration Gamma Ray Burst (GRB) 030725, which triggered the HETE FREGATE and WXM instruments on July 25th, 2003, and lasted more than 160s. An optical counterpart was…
The initial Lorentz factor ($\Gamma_{\text{0}}$) plays a crucial role in uncovering the physical characteristics of gamma-ray bursts (GRBs). Previous studies have indicated that the ambient medium density index $k$ for GRBs falls in the…
At the dawn of the gamma-ray burst (GRB) afterglow era, a Cepheid-like correlation was discovered between time variability V and isotropic-equivalent peak luminosity Liso of the prompt emission of about a dozen long GRBs with measured…
We investigate wheter there is any correlation between the X-ray afterglow luminosity and the prompt emission properties of a carefully selected sub-sample of bright Swift long Gamma-Ray Bursts (GRBs) nearly complete in redshift (~90%).…
We present results for a large number of gamma-ray burst (GRB) afterglow light curve calculations, done by combining high resolution two-dimensional relativistic hydrodynamics simulations using RAM with a synchrotron radiation code. Results…
A comprehensive temporal analysis has been performed on the 319 brightest GRBs with T90>2s from the BATSE current catalog. The rise times, fall times, full-widths at half maximum (FWHM), pulse amplitudes and pulse areas were measured and…
Opacity effects in relativistic sources of high-energy gamma-rays, such as gamma-ray bursts (GRBs) or Blazars, can probe the Lorentz factor of the outflow and the distance of the emission site from the source, and thus help constrain the…
The Gamma-Ray Optical Counterpart Search Experiment (GROCSE) presents new experimental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully-automated very wide-field opto-electronic detection…
(Abridged) We present densely sampled BVRI light curves of the optical transient associated with the gamma-ray burst GRB 030329, the result of a coordinated observing campaign conducted at five observatories. Augmented with published…
Gamma-ray bursts (GRBs) show different behaviours and trends in their spectral evolution. One of the methods used to understand the physical origin of these behaviours is to study correlation between the spectral fit parameters. In this…
The average peak-aligned profile of all bursts detected by BATSE with sufficient data quality has a simple ``stretched'' exponential shape, F ~ exp[-(t/t_0)^{1/3}], where $t$ is the time measured from the time for the peak flux of the…
We report the best evidence to date of a jet break in a short Gamma-Ray Burst (GRB) afterglow, using Chandra and Swift XRT observations of the X-ray afterglow of GRB 051221A. The combined X-ray light curve, which has three breaks, is…
From July 2008 to October 2009, the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope (FGST) has detected 320 Gamma-Ray Bursts (GRBs). About 20% of these events are classified as short based on their T90 duration…
We present a correlation between two intrinsic parameters of GRB optical afterglows. These are the isotropic luminosity at the maximum of the light curve (Lpeak) and the time-integrated isotropic energy (Eiso) radiated after the observed…
We compared the time (or time limit) of onset for optical afterglow emission to the gamma-ray variability V in 76 GRBs with redshifts. In the subset (25 cases) with the rise evident in the data, we fit the shape of the onset peak as well…
Intrinsic variability was searched for in arrival times of six gamma-ray bursts (GRBs) at high energies -- between 30 MeV and 2 GeV -- detected by the Fermi satellite's Large Area Telescope (LAT). The GRBs were selected from the Fermi LAT…
We estimate the bulk Lorentz factor Gamma_0 of 31 GRBs using the measured peak time of their afterglow light curves. We consider two possible scenarios for the estimate of Gamma_0: the case of a homogeneous circumburst medium or a wind…
I discuss some theoretical expectations for the synchrotron emission from a relativistic blast-wave interacting with the ambient medium, as a model for GRB afterglows, and compare them with observations. An afterglow flux evolving as a…