Luminosity-dependent evolution of soft X-ray selected AGN: New Chandra and XMM-Newton surveys


Por: Hasinger G., Miyaji T., Schmidt M.

Publicada: 1 ene 2005
Resumen:
We present new results on the cosmological evolution of unabsorbed (type-1) active galactic nuclei (AGN) selected in the soft (0.5-2 keV) X-ray band. From a variety of ROSAT, XMM-Newton and Chandra surveys we selected a total of ? 1000 AGN with an unprecedented spectroscopic and photometric optical/NIR identification completeness. For the first time we are able to derive reliable space densities for low-luminosity (Seyfert-type) X-ray sources at cosmological redshifts. The evolutionary behaviour of AGN shows a strong dependence on X-ray luminosity: while the space density of high-luminosity AGN reaches a peak around z ? 2, similar to that of optically selected QSO, the space density of low-luminosity AGNs peaks at redshifts below z = 1. This confirms previous ROSAT findings of a luminosity-dependent density evolution. Using a rigorous treatment of the optical identification completeness we are able to show that the space density of AGN with X-ray luminosities Lx < 10 45 ergs-1 eclines significantly towards high redshifts. © ESO 2005.
ISSN: 00046361





ASTRONOMY & ASTROPHYSICS
Editorial
EDP SCIENCES S A, 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE, Francia
Tipo de documento: Article
Volumen: 441 Número: 2
Páginas: 417-434
WOS Id: 000231958600001