Extending α OX Studies to Include the Numerous Low-to- Moderate Luminosity AGNs Aaron Steffen The Pennsylvania State University November 6th, 2006

Collaborators Iskra Strateva MPE Niel Brandt PSU David Alexander Durham, U.K. Franz Bauer Columbia Anton Koekemoer STScI Bret Lehmer PSU Don Schneider PSU Cristian Vignali INAF - Bologna

Extended Chandra Deep Field - South (E-CDF-S; Lehmer et al. 2005) Four contiguous 250 ks ACIS-I exposures centered on the 1Ms CDF-S COMBO-17 (Wolf et al. 2004) Optically selected AGNs using 5 Broad-band and 12 Medium-band filters Project Motivation ● Extend α OX studies to include the low-to-moderate luminosity AGNs that numerically dominate the AGN population. ● Break the luminosity - redshift degeneracy present in flux-limited samples. ● Compile a large, homogeneous AGN sample and use both parametric and non-parametric statistical tests to determine if α OX evolves with cosmic time.

Sobolewska, Siemiginowska & Zycki (2004) Richards et al. (2006) ● UV emission from a thermalized thin accretion disk. ● X-ray emission from inverse- Compton scattering off of energetic electrons in optically thin corona. ● Radio jets and intrinsic absorption can affect the measurement of the intrinsic X-ray/UV emission. Relation Between UV and X-ray Emission in AGN

Sample# srcs # X-ray Detected Strateva et al. (2006) Seyfert 1s25 a 25 (100%) SDSS / ROSAT (81%) High-z3632 (89%) Steffen et al. (2006) BQS / ROSAT4645 (98%) COMBO-17 / E-CDF-S5247 (90%) High-z1932 (89%) Total (88%) Sample# srcs # X-ray Detected Strateva et al. (2006) Seyfert 1s25 a 25 (100%) SDSS / ROSAT (81%) High-z3632 (89%) Steffen et al. (2006) BQS / ROSAT4645 (98%) COMBO-17 / E-CDF-S5247 (90%) High-z1932 (89%) Sample# srcs # X-ray Detected Strateva et al. (2006) Seyfert 1s25 a 25 (100%) SDSS / ROSAT (81%) High-z3632 (89%) Breaking the L-z Degeneracy

Comparing L UV and L X vs. redshift Our sample spans 5 (4) orders of magnitude in L UV (L X ).

X-ray vs. Optical Luminosity OLS Bisector yields: Non-parametric Kendall’s partial τ = (15σ)

Evidence for a non-linear relation Dependance of α OX on log(L UV ) Non-parametric Kendall’s partial τ = −0.377 (14σ)

No Evidence for Evolution Parametric Non-Parametric Kendall’s Partial τ = −0.031 (1.3σ)

Comparison with Earlier Studies AT86W94S05S06 Number of Sources % X-ray Detected 61%52%86%88% Radio Loud or BALs? Yes No

Future Studies: Including the Most Luminous AGNs Sample# srcs # X-ray Detected Strateva et al. (2006) Seyfert 1s25 a 25 (100%) SDSS / ROSAT (81%) High-z3632 (89%) Steffen et al. (2006) BQS / ROSAT4645 (98%) COMBO-17 / E-CDF-S5247 (90%) High-z1932 (89%) Total (88%) Sample# srcs # X-ray Detected Strateva et al. (2006) Seyfert 1s25 a 25 (100%) SDSS / ROSAT (81%) High-z3632 (89%) Steffen et al. (2006) BQS / ROSAT4645 (98%) COMBO-17 / E-CDF-S5247 (90%) High-z1918 (89%) Just et al. (2007) SDSS / Chandra3030 (100%) High-z1914 (74%) Total (88%)

Still no Evidence for Cosmic Evolution

Are the COMBO-17 selected AGNs the Faint Extension of the SDSS Population?

COMBO-17 α OX Distrbution