Hostname: page-component-cd9895bd7-gxg78 Total loading time: 0 Render date: 2024-12-25T16:37:45.633Z Has data issue: false hasContentIssue false
  • English
  • Français

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

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

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

References

Edelson, R., et al. 1995, Multiwavelength Monitoring of the BL Lacertae Object PKS 2155. IV. Multiwavelength Analysis, ApJ, 438, 120 Google Scholar
Fruscione, A., Bowyer, S. Konigl, A. & Kahn, S.M. 1994, Extreme Ultraviolet Spec-troscopy of PKS 2155, ApJ, 422, 55 Google Scholar
Kaastra, J.S., Roos, N. & Mewe, R. 1995, EUVE Observations of NGC 5548, Astr. Ap., submittedCrossRefGoogle Scholar
Marshall, H.L., Carone, T.E., Shull, J.M., Malkan, M.A., & Elvis, M. 1994, Conceptual Design of a Fast Soft X-ray Polarimeter, Proc. SPIE, 2283, 75 Google Scholar
Marshall, H.L., Fruscione, A., & Carone, T.E. 1995, Active Galaxies Observed during the Extreme Ultraviolet Explorer All Sky Survey., Ap. J., 439, 90 Google Scholar
Marshall, H.L., Carone, T.E., Shull, J.M., Malkan, M.A., & Elvis, M. 1995, The Steep Soft X-ray Spectrum of the Highly Variable Active Nucleus in Mk 478, ApJ, submittedGoogle Scholar
Marshall, H.L., et al. 1995, in preparationGoogle Scholar
Sun, H-S., & Malkan, M.A. 1989, Fitting improved accretion disk models to the multiwavelength continua of quasars and active galactic nuclei, ApJ, 346, 68 Google Scholar
Urry, C.M., et al. 1995, in preparationGoogle Scholar