The Sources of the CDF-N --- Classification Schemes, Absorption Estimates and Broadband SEDs Stephan Frank Patrick Osmer, Smita Mathur Extragalactic Surveys – A Chandra Science Workshop November 2006

Interesting Open Questions Fraction of obscured to unobscured sources –Ballantyne et al. (2006) : R ~ (1+z) 0.3 –Gilli et al. (2006) : R redshift independent –Luminosity dependence Where is the obscuration happening? –Mismatch between optically and X-ray derived N H (Maiolino et al. 2004) –NIR/optical/UV not at same place as X-ray α OX - L UV relation (Strateva et al. 2005; Steffen et al. 2006) –Breaks down for X-ray faint sources Absorption as main contributor Faint AGN X-ray underluminous ?

Estimating X-ray and Optical absorption NH (X-ray) (from hardness ratio NH (NIR-optical-UV) (from SED fit)

N H (X) – N H (optical) correlated ? Unabsorbed, luminous QSOsX-ray abs., opt. normal QSOs X-ray unabsorbed, Optically red QSOs X-ray absorbed, Optically red QSOs

Redshift effects for the N H estimate

Fraction of X-ray absorbed QSOs

Cf. Gilli et al. (astro-ph/ )

L x -L UV breaks down for faint AGN

α OX – L uv breaks down for faint AGN

Summary No correlation between X-ray and NIR-optical-UV absorption Fraction of X-ray absorbed QSOs –Redshift independent –Luminosity dependent α ox – L UV relation breaks down for X-ray faint QSOs –X-ray absorption main culprit –Possibly X-ray underluminous sources ? Detailed spectral analyses to disentangle host contributions necessary  multiwavelength picture Frank, Osmer, & Mathur (2006, in preparation)