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Extending α OX Studies to Include the Numerous Low-to-Moderate Luminosity AGNs

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. Franz Bauer Columbia. David Alexander Durham, U.K. Anton Koekemoer STScI.

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Extending α OX Studies to Include the Numerous Low-to-Moderate Luminosity AGNs

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  1. Extending αOX Studies to Include the Numerous Low-to-Moderate Luminosity AGNs • Aaron Steffen • The Pennsylvania State University • November 6th, 2006

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

  3. Project Motivation ● Extend αOX 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 αOX evolves with cosmic time. COMBO-17 (Wolf et al. 2004) Optically selected AGNs using 5 Broad-band and 12 Medium-band filters 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

  4. Relation Between UV and X-ray Emission in AGN Sobolewska, Siemiginowska & Zycki (2004) ● 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. Richards et al. (2006)

  5. Breaking the L-z Degeneracy

  6. Comparing LUV and LX vs. redshift Our sample spans 5 (4) orders of magnitude in LUV (LX).

  7. OLS Bisector yields: Non-parametric Kendall’s partial τ= 0.519 (15σ) X-ray vs. Optical Luminosity

  8. Non-parametric Kendall’s partial τ= −0.377 (14σ) Evidence for a non-linear relation Dependance of αOX on log(LUV)

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

  10. AT86 W94 S05 S06 Number of Sources 154 343 228 333 % X-ray Detected 61% 52% 86% 88% Radio Loud or BALs? Yes Yes No No Comparison with Earlier Studies

  11. Future Studies: Including the Most Luminous AGNs

  12. Still no Evidence for Cosmic Evolution

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

  14. COMBO-17 αOX Distrbution

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