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E.C. Moran, J.L. Connelly (Wesleyan University), C.N. Cardamone, J. Van Duyne, C.M. Urry (Yale University)
Studies of nearby X-ray galaxies have indicated that most of the hard (2--10 keV) X-ray background is produced by obscured AGNs at modest redshift. Locally, such objects have Seyfert~2 optical spectra dominated by strong, narrow emission lines. The deep Chandra\/ survey results identifying a large fraction of faint, hard X-ray sources with optically normal galaxies --- not Seyfert 2s --- have thus provided one of the major surprises of the Chandra\/ era. One possibility is that, because of their large distances and small angular sizes, the ground-based optical spectra of these objects are dominated by host galaxy emission, which makes them appear ``normal.'' To test this hypothesis, we have constructed an unbiased median spectral energy distribution (SED) for the nearby Seyfert~2 population. The Seyfert~2 SED is derived using data for 31 objects from a distance-limited sample; it covers 15 frequencies between the radio and hard X-ray bands, and to facilitate investigations of distant objects, it represents the integrated\/ emission of the galaxies. A comparison to the SEDs of distant, spectroscopically ambiguous X-ray galaxies in the Great Observatories Origins Deep Survey (GOODS) fields reveals that some objects are well matched to the Seyfert~2 SED, while others are not.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.