The X-ray-to-Optical Properties of Optically-Selected Active Galaxies Over Wide Luminosity and Redshift Ranges

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dc.creatorSteffen, A. T.
dc.creatorStrateva, I.
dc.creatorBrandt, W. N.
dc.creatorAlexander, D. M.
dc.creatorKoekemoer, A. M.
dc.creatorLehmer, B. D.
dc.creatorSchneider, D. P.
dc.creatorVignali, C.
dc.date2006-02-17
dc.date.accessioned2026-07-07T11:25:17Z
dc.date.available2026-07-07T11:25:17Z
dc.descriptionWe present partial-correlation analyses that examine the strengths of the relationships between L_UV, L_X, Alpha_OX, and redshift for optically-selected AGNs. We extend the work of Strateva et al. (2005), that analyzed optically-selected AGNs from the Sloan Digital Sky Survey (SDSS), by including 52 moderate-luminosity, optically-selected AGNs from the COMBO-17 survey with corresponding deep (~250 ks to 1 Ms) X-ray observations from the Extended Chandra Deep Field-South. The COMBO-17 survey extends ~3 magnitudes deeper than the SDSS and probes the moderate-luminosity AGNs that numerically dominate the AGN population in the Universe. We also include recently published observations of 19 high-redshift, optically-selected AGNs, and 46 luminous, low-redshift AGNs from the Bright Quasar Survey. The full sample used in our analysis consists of 333 AGNs, extending out to z~6, with 293 (88%) having X-ray detections. The sample spans five decades in UV luminosity and four decades in X-ray luminosity. We confirm that Alpha_OX is strongly anti-correlated with L_UV (13.6 sigma), the highest significance found for this relation to date, and find evidence suggesting that the slope of this relation may be dependent on L_UV. We find that no significant correlation exists between Alpha_OX and redshift (1.3 sigma), and constrain the maximum evolution of AGN UV-to-X-ray flux ratios to be less than 30% (1 sigma) out to z=5. Using our sample's high X-ray detection fraction, we also find a significant anti-correlation (3.0 sigma) between Alpha_OX and L_X . We make comparisons to earlier studies on this topic and discuss implications for X-ray vs. optical luminosity functions.
dc.description16 pages, 10 figures, emulateapj. Accepted for publication in AJ
dc.identifierhttps://arxiv.org/abs/astro-ph/0602407
dc.identifierhttp://arxiv.org/abs/astro-ph/0602407
dc.identifierAstron.J.131:2826-2842,2006
dc.identifierdoi:10.1086/503627
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/195461
dc.subjectAstrophysics
dc.titleThe X-ray-to-Optical Properties of Optically-Selected Active Galaxies Over Wide Luminosity and Redshift Ranges
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