NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-20 T01:29:01 PDT
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For refcode 1992MNRAS.254...30G:
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NED Abstract

Copyright by Royal Astronomical Society. 1992MNRAS.254...30G A compilation of active and normal galaxies observed in both infrared and X-rays Paul J. Green, Scott F. Anderson and Martin J. Ward Department of Astronomy, FM-20, University of Washington, Seattle, WA 98195 USA Department of Physics, Nuclear Physics Building, Keble Road, University of Oxford, Oxford OX1 3RH Accepted 1991 August 13. Received 1991 July 22; in original form 1991 May 1. SUMMARY For the largest ensemble of active and normal galaxies to date, we have collected far-infrared and X-ray data from the literature and from the IRAS and Einstein databases. We study the relation between emission in these two bands, using survival analysis to exploit the information contained in upper limits. We find that galaxies with soil X-ray to infrared flux ratios greater than about 0.01 are almost certain to show broad-line optical emission. This discriminant will be valuable for finding quasars and Seyfert 1 galaxies from comparisons of IR and X-ray surveys. A sensitive, all-sky X-ray survey like ROSAT is particularly well-suited to such a search in conjunction with the IRAS data. For the full IRAS/Einstein ensemble, we find a significant correlation between luminosities in the 60-micron and 0.5-4.5 keV bands. A strong offset separates broad-line from normal and narrow-line galaxies. We interpret the jump toward higher X-ray emission in broad-line galaxies as evidence for the increasing importance of a non-thermal nuclear source. Among individual galaxy classes, radio-loud quasars show a significant correlation of L_x_ to L_60 microns_ that is not seen in radio-quiet quasars or Seyferts as individual classes. Since the ratios L_x_/L_60 microns_ differ significantly between predominantly thermal and non-thermal nuclear components, we conjecture that the correlations intrinsic to each individual component are lost when the two are strongly mixed in Seyfert galaxies or radio-quiet quasars. Our analysis of the empirical relationship between L_x_ and L_60 microns_ for normal and narrow optical emission-line galaxies (excluding Seyfert 2s) allows us to convert published 60-micron IRAS luminosity functions into estimates of the 2-keV X-ray luminosity function of IR-emitting galaxies. We use this luminosity function to estimate the contribution to the soil X-ray background of these lower luminosity IR-emitting galaxies out to Z_max_ = 3. Depending on the evolutionary model applied, we derive contributions of 5-25 per cent for these galaxies to the soft X-ray background.
Retrieve 269 NED objects in this reference.
Please click here for ADS abstract

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