Related papers: Construction and Preliminary Application of the Va…
The work is devoted to the search for possible effect of gravitational lensing on the objects like globular stellar clusters (mesolensing) on the lightcurves and spectra of large number of gamma-ray bursts from BATSE catalogue. The general…
I show how an empirical variability - luminosity relationship for prompt gamma-ray bursts, first proposed by Fenimore and Ramirez-Ruiz, can be understood as a special-relativistic beaming effect in the ``cannonball model'' of Dar and De…
We compute the luminosity function (LF) and the formation rate of long gamma ray bursts (GRBs) by fitting the observed differential peak flux distribution obtained by the BATSE experiment in two different scenarios: i) the GRB luminosity…
The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities…
We have investigated the time variations in the light curves from a sample of long and short Fermi/GBM Gamma ray bursts (GRBs) using an impartial wavelet analysis. The results indicate that in the source frame, the variability time scales…
The methods of calibrating the luminosities of galactic Cepheids and determining Cepheid reddenings are considered in some detail. Together with work on NGC4258 this suggests that the calibration presented is valid to about 0.1mag (s.e.) at…
The gamma-ray burst's lightcurves have been analyzed using a special wavelet transformation. The applied wavelet base is based on a typical Fast Rise-Exponential Decay (FRED) pulse. The shape of the wavelet coefficients' total distribution…
Kouveliotou et al. (1993) recently confirmed that gamma-ray bursts are bimodal in duration. In this paper we compute the statistical properties of the short ($\le 2$~s) and long ($>2$~s) bursts using a method of analysis that makes no…
In recent years there has been considerable activity in using gamma-ray bursts as cosmological probes for determining global cosmological parameters complementing results from type Ia supernovae and other methods. This requires a…
Clustering is an important tool to describe gamma-ray bursts (GRBs). We analyzed the Final BATSE Catalog using Gaussian-mixture-models-based clustering methods for six variables (durations, peak flux, total fluence and spectral hardness…
The Fermi GBM catalog provides a large database with many measured variables that can be used to explore and verify gamma-ray burst classification results. We have used Principal Component Analysis and statistical clustering techniques to…
Gamma-ray bursts are still not fully understood events. However, their exploration could provide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers…
Two classes of gamma-ray bursts (GRBs), short and long, have been determined without any doubts, and are usually ascribed to different progenitors, yet these classes overlap for a variety of descriptive parameters. A subsample of 46 long…
The recent discovery that faint gamma-ray bursts are stretched in time relative to bright ones has been interpreted as support for cosmological distances: faint bursts have their durations redshifted relative to bright ones. It was pointed…
Gamma-ray bursts (GRBs) are generally categorized into long and short bursts based on their duration ($T_{90}$). Recently, it has been proposed that GRBs can also be classified into type I (merger) and type II (collapsar) bursts based on…
We present here our results of the temporal and spectral analysis of a sample of 52 bright and hard gamma-ray bursts (GRBs) observed with the Fermi Gamma-ray Burst Monitor (GBM) during its first year of operation (July 2008-July 2009). Our…
In the use and interpretation of $\log{N}$--$\log{S}$ distributions for gamma-ray bursts, burst peak flux has typically been used for $S$. We consider here the use of the fluence as a measure of $S$, which may be a more appropriate quantity…
We use the BD2 sample of gamma-ray bursts (GRBs) based on 5.9 years of BATSE DISCLA data with a variety of models of the luminosity function to derive characteristic GRB luminosities, space densities and redshift distributions. Previously…
We report test results of the correlation between time variability and peak luminosity of Gamma-Ray Bursts (GRBs), using a larger sample (32) of GRBs with known redshift than that available to Reichart et al. (2001), and using as…
Using the lag-luminosity relation and various BATSE catalogs we create a large catalog of burst redshifts, peak luminosities and emitted energies. These catalogs permit us to evaluate the lag-luminosity relation, and to study the burst…