Non-Equilibrium Ionization States of GRB Environments
Abstract
Iron spectral features are thought to be the best tracer of a progenitor of gamma-ray bursts (GRBs). The detections of spectral features such as an iron line and/or a Radiative Recombination edge and Continuum (RRC) were reported in four X-ray afterglows of GRBs. However their properties were different each other burst by burst. For example, Chandra observation of GRB 991216 reported both the strong H-like iron line together with its RRC. On the contrary, Yoshida et al. (2001) report only a detection of the strong RRC in GRB 970828 with ASCA. Since it is difficult to produce the strong RRC, we have to consider special condition for the line and/or the RRC forming region. In this paper, we point out a possibility of a ``non-equilibrium ionization state'' for the line and the RRC forming region.
Keywords
Cite
@article{arxiv.astro-ph/0107330,
title = {Non-Equilibrium Ionization States of GRB Environments},
author = {D. Yonetoku and T. Murakami and K. Masai and A. Yoshida and N. Kawai and M. Namiki},
journal= {arXiv preprint arXiv:astro-ph/0107330},
year = {2009}
}
Comments
10pages, 2figures. Accepted for ApJL. This is a companion paper by A.Yoshida et. al