We present results from the photometric and spectroscopic identification of 122 X-ray sources recently discovered by XMM-Newton in the 2-10 keV band (the HELLAS2XMM 1 dF sample). One of the most interesting results (which is found also in deeper surveys) is that similar to 20% of the sources have an X-ray to optical flux ratio (X/O) ten times or more higher than that of optically selected AGN. Unlike the faint sources found in the ultra-deep Chandra and XMM-Newton surveys, which reach X-ray (and optical) fluxes 10 times lower than in the HELLAS2XMM sample, many of the extreme X/O sources in our sample have R less than or similar to 25 and are therefore accessible to optical spectroscopy. We report the identification of 13 sources with extreme X/O values. While four of these sources are broad line QSO, eight of them are narrow line QSO, seemingly the extension to very high luminosity of the type 2 Seyfert galaxies.
Fiore, F., Brusa, M., Cocchia, F., Baldi, A., Carangelo, N., Ciliegi, P., et al. (2004). The HELLAS2XMM 1dF survey: On the nature of high X-ray/optical flux sources. In MULTIWAVELENGTH COSMOLOGY (pp.283-286). Attuale: SPRINGER, VAN GODEWIJCKSTRAAT 30, DORDRECHT, NETHERLANDS, 3311 GZ -Kluwer Academic Publishers:Journals Department, PO Box 322, 3300 AH Dordrecht Netherlands:011 31 78 6576050, EMAIL: frontoffice@wkap.nl, kluweronline@wkap.nl, INTERNET: http://ww.
The HELLAS2XMM 1dF survey: On the nature of high X-ray/optical flux sources
LA FRANCA, Fabio;Matt G;
2004-01-01
Abstract
We present results from the photometric and spectroscopic identification of 122 X-ray sources recently discovered by XMM-Newton in the 2-10 keV band (the HELLAS2XMM 1 dF sample). One of the most interesting results (which is found also in deeper surveys) is that similar to 20% of the sources have an X-ray to optical flux ratio (X/O) ten times or more higher than that of optically selected AGN. Unlike the faint sources found in the ultra-deep Chandra and XMM-Newton surveys, which reach X-ray (and optical) fluxes 10 times lower than in the HELLAS2XMM sample, many of the extreme X/O sources in our sample have R less than or similar to 25 and are therefore accessible to optical spectroscopy. We report the identification of 13 sources with extreme X/O values. While four of these sources are broad line QSO, eight of them are narrow line QSO, seemingly the extension to very high luminosity of the type 2 Seyfert galaxies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
