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Variability and Spectra of AGN in the EUV and the Relation to Other Bands

Published online by Cambridge University Press:  12 April 2016

Herman L. Marshall
Herman L. Marshall*
Affiliation:
Eureka Scientific, Inc., 5 Whipple Rd., Lexington, MA, 02173, USA

Abstract

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Data from several collaborations will be shown which demonstrate the utility of EUVE observations. For Mk 478, a Seyfert 1 galaxy, the rapidly variable EUV flux is shown to have a steep, featureless continuum. The EUV data are combined with UV and optical data to form an overall spectrum that is consistent with an accretion disk model; slight temperature variations in the innermost regions could cause the large EUV flux changes. EUVE data for other sources are presented: NGC 5548, which shows significant variations and has an EUV spectrum that shows no emission lines, contrary to a previous report; 3C 273, which did not vary much; and PKS 2155-304, which was observed simultaneously with ASCA and IUE when a hard X-ray flare was detected as an EUV polarization measurement was being attempted.

Type
II. Extragalactic Sources in the EUV
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 63 - 67
Copyright
Copyright © Kluwer 1996

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