INVESTIGATION OF ELEMENT ABUNDANCES IN THE SURROUNDINGS OF GRB AFTERGLOWS

摘要

In the case of high energy collimated outflows it is important to know the density and structure of material through which jets propagate. Here we present a simple study of the environment of GRBs where the relativistic ejecta travel during the event. We use observed spectral lines in the afterglow of gamma-ray bursts and by constructing the curve of growth for most redshifted lines, we extract the column densities and Doppler parameter. This can give us the overall picture of abundances in the vicinity of GRBs. Also, we compare this result with the spectral lines with lower redshift to examine the dependence of elemental abundances on the distance from GRB event.