X-ray spectral features from GRBs: Predictions of progenitor models

Abstract

We investigate the potentially observable prompt or delayed X-ray spectral features from the currently popular gamma-ray burst (GRB) models. During the evolution of many GRB progenitors, a disk around the central GRB source is produced. Shock heating as the GRB ejecta collide with the disk may produce observable X-ray features. We first summarize predictions deduced from previous calculations which invoke photoionization and relativistic blast waves. We then calculate the quasi-thermal X-ray line features produced assuming the ejecta are nonrelativistic (which is more likely for the disk interactions of many GRB models). 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 <~ a few days after the GRB. These X-ray signatures should be observable with Chandra and XMM-Newton out to at least z ~ 1. 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 might result from compact-object binary mergers.

20 pages, including 8 figures and 3 tables. Uses epsf.sty, rotate.sty. Final version, accepted for publication in to ApJ. Revised analytical estimate of maximum emission line luminosity. Numerical results and conclusions unchanged

References in corpus (5)

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• On the anomalous X-ray afterglows of GRB 970508 and GRB 970828
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