1997/10/31 by Boyle, B. J., B. J. Boyle, Georgantopoulos, I. +13 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Emission spectrum #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Luminosity function #Power law #QSOS #ROSAT #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1998.01098.x
10 pages, TeX, 5 figures, MNRAS in press (significant revision at proof stage)
arxiv created 1997/11/26 · openalex publication_date 1998/05/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present additional optical spectroscopic identifications of sources identified in three deep ASCA GIS fields which also form part of a deep ROSAT survey. In total, 26 ASCA sources have been detected down to a 2-10keV flux limit of S = 5e-14 erg/cm/s. LDSS observations have increased the spectroscopic completeness of the survey to between 65 and 85 per cent, with identifications for up to 13 QSOs with broad emission lines and 6 objects with narrow emission lines. Combining these objects with the AGN identified in the LMA/HEAO-1 sample by Grossan, we find evidence for significant cosmological evolution in the 2-10keV band (<Ve/Va>=0.63+/-0.03), fit by a pure luminosity evolution model; L ∝ (1+z)k, k=2.04+0.16-0.22. The present-epoch 2-10keV AGN X-ray luminosity function, Φ(LX), is best represented by a two power law function: Φ(LX) ∝ L-3.0, L*>1044.1erg/s; Φ (LX) ∝ L-1.9, L*<1044.1erg/s. Depending on the extent to which we extrapolate the z=0 AGN luminosity function, we predict a total contribution to the 2-10keV X-ray background from QSOs and narrow-emission-line galaxies which ranges from 48 per cent (for AGN with L>1042erg/s) to 80 per cent (L>1039erg/s).