NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-26 T06:34:42 PDT
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For refcode 2006A&A...446..459C:
Retrieve 27 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2006A&A...446..459C X-ray spectral survey with XMM-Newton of a complete sample of nearby Seyfert galaxies M. Cappi, F. Panessa, L. Bassani, M. Dadina, G. DiCocco, A. Comastri, R. Della Ceca, A. V. Filippenko, F. Gianotti, L. C. Ho, G. Malaguti, J. S. Mulchaey, G. G. C. Palumbo, E. Piconcelli, W. L. W. Sargent, J. Stephen, M. Trifoglio and K. A. Weaver Received 23 July 2005 / Accepted 28 September 2005 Results obtained from an X-ray spectral survey of nearby Seyfert galaxies using XMM-Newton are reported. The sample was optically selected, well defined, complete in B magnitude, and distance limited: it consists of the nearest (D ~< 22 Mpc) 27 Seyfert galaxies (9 of type 1, 18 of type 2) taken from the Ho et al. (1997a, ApJS, 112, 315) sample. This is one of the largest atlases of hard X-ray spectra of low-luminosity active galaxies ever assembled. All nuclear sources except two Seyfert 2s are detected between 2 and 10 keV, half for the first time ever, and average spectra are obtained for all of them. Nuclear luminosities reach values down to 10^38^ erg s^-1^. The shape of the distribution of X-ray parameters is affected by the presence of Compton-thick objects ( >~ 30% among type 2s). The latter have been identified either directly from their intense FeK line and flat X-ray spectra, or indirectly with flux diagnostic diagrams which use isotropic indicators. After taking into account these highly absorbed sources, we find that (i) the intrinsic X-ray spectral properties (i.e., spectral shapes and luminosities above 2 keV) are consistent between type 1 and type 2 Seyferts, as expected from "unified models"; (II) Seyfert galaxies as a whole are distributed fairly continuously over the entire range of N_H_, between 10^20^ and 10^25^ cm^-2^; and (III) while Seyfert 1s tend to have lower N_H_ and Seyfert 2s tend to have the highest, we find 30% and 10% exceptions, respectively. Overall the sample is of sufficient quality to well represent the average intrinsic X-ray spectral properties of nearby active galactic nuclei, including a proper estimate of the distribution of their absorbing columns. Finally, we conclude that, with the exception of a few cases, the present study agrees with predictions of unified models of Seyfert galaxies, and extends their validity down to very low luminosities. Key words: X-rays: galaxies, galaxies: Seyfert, glaxies: active
Retrieve 27 NED objects in this reference.
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