Attila Meszaros

Estimation of the Redshifts for Long Gamma‐Ray Bursts

It is known that the soft tail of gamma‐ray bursts’ spectra show excesses from the exact power‐law dependence. In this article we show that this departure can be detected in the peak flux ratios of different BATSE DISCSC energy channels. This effect allows us to estimate the redshifts of bright long gamma‐ray bursts given in the BATSE Catalog. For the 8 gamma‐ray bursts, which have both BATSE DISCSC data and measured optical spectroscopic redshifts, the correlation between the true and estimated redshifts is remarkable, and the average error is Δz ≈ 0.5. The method is similar to the photometric redshift estimation of galaxies in the optical range, hence we call it “gamma photometric redshift estimation”. These redshifts for the remaining 857 long bright gamma‐ray bursts are are up to z ≃ (4 – 7). For the the faint long bursts — which should be up to z ≃ 20 — the redshifts hardly can be determined unambiguously from this method.

Astronomical Aspects of Multifractal Point-Pattern Analysis: Application to the DENIS/2MASS Near-Infrared and BATSE Gamma-Ray Data

Two applications of the multifractal (MFR) point pattern analysis are presented. First, we study the angular distribution of subclasses of gamma-ray bursts (GRBs), then we analyse the structure of extinction maps of dark molecular clouds obtained by near-infrared (NIR) star counts.

An Observational Evidence for the Difference Between the Short and Long Gamma‐Ray Bursts

The intrinsic fluence and duration distributions of gamma‐ray bursts are well represented by log‐normal distributions. This allows a bivariate log‐normal distribution fit to be made to the BATSE short and long bursts separately. A statistically significant difference between the long and short groups is found. We argue that the effect is probably real. Applying the Cramer’s theorem these results lead to some predictions for models of long and short bursts.