NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T09:06:40 PDT
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For refcode 1989ApJ...344..125P:
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Copyright by American Astronomical Society. Reproduced by permission
1989ApJ...344..125P CONTRIBUTIONS OF LOW-LUMINOSITY SOURCES TO THE X-RAY BACKGROUND M. PERSIC, G. DE ZOTTI, L. DANESE, G. G. C. PALUMBO, A. FRANCESCHINI E. A. BOLDT AND F. E. MARSHALL Received 1987 October 12, accepted 1989 February 27 ABSTRACT We have exploited the HEAO 1 A-2 data base to determine hard X-ray fluxes, or upper limits, for complete optically selected samples of active and normal galaxies, in order to estimate or to constrain their local X-ray luminosity functions. We find that the luminosity function of Seyfert nuclei must flatten down drastically shortly below the observational limit of Piccinotti et al.; little can be added by dwarf active nuclei hidden in otherwise normal galaxies. We also analyze the possible contribution to the X-ray background from galaxies with strong star formation activity, in the light of the possibility of a substantial cosmological evolution suggested by recent radio and IRAS data. Subject headings: galaxies: nuclei - galaxies: Seyfert - galaxies: stellar content - galaxies: X-rays - X-rays: sources
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