The UV-TO-X-ray emission ratio in AGN: Luminosity dependence and no redshift evolution

I. Strateva, A. Steffen, W. Brandt, D. Alexander, A. Koekemoer, B. Lehmer, D. Schneider, C. Vignali

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We compiled a relatively homogeneous sample of 332 optically-selected, radio-quiet, unabsorbed AGN with the largest redshift range coverage (0 < z < 6) and X-ray detection fraction to date (88%). Using partial-correlation analysis, we confirm that the soft X-ray emission from AGN is strongly correlated with their UV emission (partial Kendall's τ = 0.52 at 15.4σ) despite the dependence of luminosity on redshift in flux-limited samples. The UV-to-X-ray emission ratio, αox = -0.384log[L 2500Å/L2keV], is related to the AGN luminosity (in the sense that less luminous AGN emit more soft X-rays per unit UV), but remains unchanged with cosmic time.

Original languageEnglish (US)
Title of host publicationX-ray Universe 2005
Number of pages2
StatePublished - 2006
EventX-ray Universe 2005 - Madrid, Spain
Duration: Sep 26 2005Sep 30 2005

Publication series

NameEuropean Space Agency, (Special Publication) ESA SP
ISSN (Print)0379-6566


OtherX-ray Universe 2005

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science


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