An Attempt to Calculate Average Redshift of Optically Dark GRBs

Abstract

Dark Gamma Ray Bursts (DGRBs) are those in which Optical-to-X-ray spectral index (β_OX) is expected to be equal to or less than 0.5 of canonical GRB afterglow. High Redshift is also considered as one of the reason behind it. Here we present a carefully selected sample of Dark GRBs, to estimate unbiased GRB mean redshift (z_mean). An attempt has been made in the present work to find correlations between various GRBs and host properties.