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An XMM‐Newton study of hard X‐ray sources
Author(s) -
Piconcelli E.,
Bassani L.,
Cappi M.,
Fiore F.,
Di Cocco G.,
Stephen J.B.
Publication year - 2003
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200310060
Subject(s) - physics
We briefly report on an on-going spectroscopic study of hard X-ray sourcesselected serendipitously in 12 XMM-Newton fields. Results for the analysis ofthe 41 sources from the first seven EPIC observations have been discussed in aprevious paper (Piconcelli et al. 2002, Paper I) where we found an absolutefraction of X-ray absorbed sources (~30%) lower than expected (~50%) by thepredictions of popular CXB synthesis models at F(2-10)~5x10**(-14) erg cm**-2s**-1. We present here the preliminary results concerning the whole sampleincluding five new deeper XMM-Newton measurements increasing the sample to 90sources. Even if still on-going, the present study appears to confirm andextend down to F(2-10)~10**(-14) erg cm**-2 s**-1 the above mismatch betweenobservational data and theoretical expectations regarding the fraction ofabsorbed sources. Furthermore the sample average spectral index of 1.5-1.6 issteeper than the CXB slope indicating that the majority of obscured sourcesmaking the bulk of the CXB resides at even lower hard X-ray fluxes.Comment: Proceedings for the "X-ray Surveys: in the light of new observatories" Workshop (to be published in Astron. Nachrichten; includes anabs.cls style file). One page and two figure