ASCA observations of the galactic bulge hard x-ray source GRS 1758--258
Abstract
GRS 1758-258 is one of the few persistent hard X-ray emitters (E>100 keV) in the Galaxy. Using the ASCA satellite, we have obtained the first detailed data on GRS 1758-258 in the 1-10 keV range, where previous observations were affected by confusion problems caused by the nearby strong source GX5-1. The spectrum is well described by a power law with photon index 1.7 without strong Fe emission lines. A prominent soft excess, as observed with ROSAT when the hard X-ray flux was in a lower intensity state, was not detected. However, the presence of a soft spectral component, accounting for at most 5% of the 0.1-300 keV flux, cannot be excluded. The accurate measurement of interstellar absorption (N_H=(1.5+-0.1) x 10^22 cm -2) corresponds to an optical extinction which definitely excludes the presence of a massive companion.
Cite
@article{arxiv.astro-ph/9609056,
title = {ASCA observations of the galactic bulge hard x-ray source GRS 1758--258},
author = {S. Mereghetti and D. I. Cremonesi and F. Haardt and T. Murakami and T. Belloni and A. Goldwurm},
journal= {arXiv preprint arXiv:astro-ph/9609056},
year = {2009}
}
Comments
7 pages, AAS latex [11pt,aaspptwo,flushrt,tighten], + 1.ps figure Accepted for pubblication in ApJ, 09 02 96 Also available at http://fy.chalmers.se/~haardt/personal/curr.html Figures 1 and 2 available upon request at [email protected]