NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-20 T22:54:59 PDT
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For refcode 1995ApJ...439...90M:
Retrieve 194 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1995ApJ...439...90M ACTIVE GALAXIES OBSERVED DURING THE EXTREME ULTRAVIOLET EXPLORER ALL-SKY SURVEY H. L. MARSHALL, A. FRUSCIONE, AND T. E. CARONE Center for EUV Astrophysics, 2150 Kittredge Street, University of California, Berkeley, CA 94720 Received 1994 March 18; accepted 1994 July 28 ABSTRACT We present observations of active galactic nuclei (AGNs) obtained with the Extreme Ultraviolet Explorer (EUVE) during the all-sky survey. A total of 13 sources were detected at a significance of 2.5 {sigma} or better: seven Seyfert galaxies, five BL Lac objects, and one quasar. The fraction of BL Lac objects is higher in our sample than in hard X-ray surveys but is consistent with the soft X-ray Einstein Slew Survey, indicating that the main reason for the large number of BL Lac objects detected in the extreme ultraviolet (EUV) and soft X-ray bands is their steeper X-ray spectra. We show that the number of AGNs observed in both the EUVE and ROSAT Wide Field Camera surveys can readily be explained by modelling the EUV spectra with a simple power law in the case of BL Lac objects and with an additional EUV excess in the case of Seyferts and quasars. Allowing for cold matter absorption in Seyfert galaxy hosts drive up the inferred average continuum slope to 2.0 +/- 0.5 (at 90% confidence), compared to a slope of 1.0 usually found from soft X-ray data if Seyfert galaxies without EUV excesses form a significant fraction of the population, then the average spectrum of those with bumps should be even steeper. We place a conservative limit on neutral gas in BL Lac objects: N_H_ < 10^20^ cm^- 2^. Subject headings: BL Lacertae objects: general - galaxies: active - galaxies: Seyfert - surveys - ultraviolet: galaxies
Retrieve 194 NED objects in this reference.
Please click here for ADS abstract

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