The nature of the unresolved extragalactic soft CXB
Abstract
In this paper we investigate the power spectrum of the unresolved 0.5-2 keV CXB with deep Chandra 4 Ms observations in the CDFS. We measured a signal which, on scales >30", is significantly higher than the Shot-Noise and is increasing with the angular scale. We interpreted this signal as the joint contribution of clustered undetected sources like AGN, Galaxies and Inter-Galactic-Medium (IGM). The power of unresolved cosmic sources fluctuations accounts for \sim 12% of the 0.5-2 keV extragalactic CXB. Overall, our modeling predicts that \sim 20% of the unresolved CXB flux is made by low luminosity AGN, \sim 25% by galaxies and \sim 55% by the IGM (Inter Galactic Medium). We do not find any direct evidence of the so called Warm Hot Intergalactic Medium (i.e. matter with 10^5K<T<10^7K and density contrast {\delta} <1000), but we estimated that it could produce about 1/7 of the unresolved CXB. We placed an upper limit to the space density of postulated X-ray-emitting early black hole at z>7.5 and compared it with SMBH evolution models.
Keywords
Cite
@article{arxiv.1208.4105,
title = {The nature of the unresolved extragalactic soft CXB},
author = {N. Cappelluti and P. Ranalli and M. Roncarelli and P. Arevalo and G. Zamorani A. Comastri and R. Gilli and E. Rovilos and C. Vignali and V. Allevato and A. Finoguenov and T. Miyaji and F. Nicastro and I. Georgantopoulos and A. Kashlinsky},
journal= {arXiv preprint arXiv:1208.4105},
year = {2012}
}
Comments
15 pages, 9 figures, accepted by MNRAS