Abstract
We investigate the currently most popular models of gamma-ray burst (GRB) progenitors in terms of potentially observable prompt or delayed X-ray spectral features. We focus on quasi-thermal X-ray line features from ejecta of a supernova related to the GRB. In the framework of the Hypernova/Collapsar model, delayed (a few days - several months after the GRB) bursts of line-dominated, thermal X-ray emission may be expected. The He-merger scenario predicts similar X-ray emission line bursts in the days following the the GRB. These X-ray signatures should be observable with Chandra and XMM out to rather large redshifts. Weak emission line features a few days after the GRB may also result from the supranova GRB scenario. In all three cases, significant X-ray absorption features, in particular during the prompt GRB phase, are expected. No significant X-ray spectral features result from compact-object binary mergers.
