Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-10-02
Astronomy and Astrophysics
Astrophysics
Accepted for publication in A&A. 12 pages, 12 figures
Scientific paper
10.1051/0004-6361:200810168
One of the most important parameters in the XRB (X-ray background) synthesis models is the average efficiency of accretion onto SMBH (super-massive black holes). This can be inferred from the shape of broad relativistic Fe lines seen in X-ray spectra of AGN (active galactic nuclei). Several studies have tried to measure the mean Fe emission properties of AGN at different depths with very different results. We compute the mean Fe emission from a large and representative sample of AGN X-ray spectra up to redshift ~ 3.5. We developed a method of computing the rest-frame X-ray average spectrum and applied it to a large sample (more than 600 objects) of type 1 AGN from two complementary medium sensitivity surveys based on XMM-Newton data, the AXIS and XWAS samples. This method makes use of medium-to-low quality spectra without needing to fit complex models to the individual spectra but with computing a mean spectrum for the whole sample. Extensive quality tests were performed by comparing real to simulated data, and a significance for the detection of any feature over an underlying continuum was derived. We detect with a 99.9% significance an unresolved Fe K-alpha emission line around 6.4 keV with an EW ~ 90 eV, but we find no compelling evidence of any significant broad relativistic emission line in the final average spectrum. Deviations from a power law around the narrow line are best represented by a reflection component arising from cold or low-ionization material. We estimate an upper limit for the EW of any relativistic line of 400 eV at a 3 sigma confidence level. We also marginally detect the so-called Iwasawa-Taniguchi effect on the EW for the unresolved emission line, which appears weaker for higher luminosity AGN.
Barcons Xavier
Carrera Francicso J.
Corral Alvaro
Ebrero Jacobo
Krumpe Mirko
No associations
LandOfFree
Average Fe K-alpha emission from distant AGN does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Average Fe K-alpha emission from distant AGN, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Average Fe K-alpha emission from distant AGN will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-492819