extending α ox studies to include the numerous low-to-moderate luminosity agns
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Extending αOX Studies to Include the Numerous Low-
to-Moderate Luminosity AGNs
Aaron SteffenThe Pennsylvania State University
November 6th, 2006
Collaborators
Iskra StratevaMPE
Niel BrandtPSU
David AlexanderDurham, U.K.
Franz BauerColumbia
Anton KoekemoerSTScI
Bret LehmerPSU
Don SchneiderPSU
Cristian VignaliINAF - 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 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.
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 1s 25a 25 (100%)
SDSS / ROSAT 155126
(81%)
High-z 36 32 (89%)
Steffen et al. (2006)
BQS / ROSAT 46 45 (98%)
COMBO-17 / E-CDF-S
52 47 (90%)
High-z 19 32 (89%)
Total 333293
(88%)
Sample#
srcs# X-ray
Detected
Strateva et al. (2006)
Seyfert 1s 25a 25 (100%)
SDSS / ROSAT 155126
(81%)
High-z 36 32 (89%)
Steffen et al. (2006)
BQS / ROSAT 46 45 (98%)
COMBO-17 / E-CDF-S
52 47 (90%)
High-z 19 32 (89%)
Sample#
srcs# X-ray
Detected
Strateva et al. (2006)
Seyfert 1s 25a 25 (100%)
SDSS / ROSAT 155126
(81%)
High-z 36 32 (89%)
Breaking the L-z Degeneracy
Comparing LUV and LX vs. redshift
Our sample spans 5 (4) orders of magnitude in LUV (LX).
X-ray vs. Optical Luminosity
OLS Bisector yields:
Non-parametric
Kendall’s partial τ = 0.519 (15σ)
Evidence for a non-linear relation
Dependance of αOX on log(LUV)
Non-parametric Kendall’s
partial τ = −0.377 (14σ)
No Evidence for Evolution
ParametricNon-Parametric
Kendall’s Partial τ = −0.031 (1.3σ)
Comparison with Earlier Studies
AT86
W94 S05 S06
Number of Sources
154 343 228 333
% X-rayDetected
61% 52% 86% 88%
Radio Loud or BALs?
Yes Yes No No
Future Studies: Including the Most Luminous AGNs
Sample#
srcs# X-ray
Detected
Strateva et al. (2006)
Seyfert 1s 25a 25 (100%)
SDSS / ROSAT 155126
(81%)
High-z 36 32 (89%)
Steffen et al. (2006)
BQS / ROSAT 46 45 (98%)
COMBO-17 / E-CDF-S
52 47 (90%)
High-z 19 32 (89%)
Total 333293
(88%)
Sample#
srcs# X-ray
Detected
Strateva et al. (2006)
Seyfert 1s 25a 25 (100%)
SDSS / ROSAT 155126
(81%)
High-z 36 32 (89%)
Steffen et al. (2006)
BQS / ROSAT 46 45 (98%)
COMBO-17 / E-CDF-S
52 47 (90%)
High-z 19 18 (89%)
Just et al. (2007)
SDSS / Chandra 3030
(100%)
High-z 19 14 (74%)
Total 382337
(88%)
Still no Evidence for Cosmic Evolution
Are the COMBO-17 selected AGNs the Faint Extension of the SDSS
Population?
COMBO-17 αOX Distrbution