X-ray spectra of XMM-Newton AXIS serendipitous sources

Abstract

We have carried out a broad-band spectral analysis of X-ray sources detected serendipitously with the EPIC-pn instrument onboard XMM-Newton in AXIS fields. Our total catalogue contains 1837 X-ray sources detected in the energy band 0.5-4.5 keV down to a flux of ~ 3x 10^-15 erg cm^-2 s^-1. Optical identifications are available for 190 sources: 119 broad-line AGN (BLAGN), 23 narrow-line emitting galaxies (NELG), 12 normal galaxies, 34 stars, 1 cluster and 1 BL Lac. We have first fitted individual broad-band spectra with a single power law model plus Galactic absorption. An analysis of these fits as a whole reveals that this model is not appropriate for the overall population, nor is it for the BLAGNs. We have then refitted the spectra with an absorbed power law model. In this case there is a significant improvement in the spectral fits as a whole. However, detection of absorption in individual sources has not been possible with the current approach and will have to await for a more refined analysis.