High Energy Break and Reflection Features in the Seyfert Galaxy MCG+8-11-11
Abstract
We present the results from ASCA and OSSE simultaneous observations of the Seyfert 1.5 galaxy MCG+8-11-11 performed in August-September 1995. The ASCA observations indicate a modest flux increase (20%) in 3 days, possibly correlated to a softening of the 0.6-9 keV spectrum. The spectrum is well described by a hard power law (Gamma=1.64) absorbed by a column density slightly larger than the Galactic value, with an iron line at 6.4 keV of EW=400 eV. The simultaneous OSSE data are characterized by a much softer power law with photon index Gamma=3.0, strongly suggesting the presence of a spectral break in the hard X/soft gamma-ray band. A joint fit to OSSE and ASCA data clearly shows an exponential cut-off at about 300 keV, and strong reflection component. MCG+8-11-11 features a spectral break in the underlying continuum unambiguously. This, together with the inferred low compactness of this source, favours thermal or quasi-thermal electron Comptonization in a structured Corona as the leading process of high energy radiation production.
Cite
@article{arxiv.astro-ph/9711242,
title = {High Energy Break and Reflection Features in the Seyfert Galaxy MCG+8-11-11},
author = {P. Grandi and F. Haardt and G. Ghisellini and E. J. Grove and L. Maraschi and C. M. Urry},
journal= {arXiv preprint arXiv:astro-ph/9711242},
year = {2009}
}
Comments
13 pages, + 4 figure.ps AAS LateX [11pt,aasms4]{article} To be published in ApJ, Main Journal