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Accretion disk emission from a BL Lacertae objectIt is suggested here that the UV and X-ray emission of BL Lac objects may originate in an accretion disk. Using detailed calculations of accretion disk spectra, the best-measured ultraviolet and soft X-ray spectra of the BL Lac object PKS 2155-304 are fitted, and the mass and accretion rate required is determined. The ultraviolet through soft X-ray continuum is well fitted by the spectrum of an accretion disk, but near-Eddington accretion rates are required to produce the soft X-ray excess. A hot disk or corona could Comptonize soft photons from the cool disk and produce the observed power-law spectrum in the 1-10 keV range. The dynamic time scale in the disk regions that contribute most of the observed ultraviolet and soft X-ray photons are consistent with the respective time scales for intensity variations observed in these two wave bands; the mass derived from fitting the continuum spectrum is consistent with the limit derived from the fastest hard X-ray variability.
Document ID
19910037135
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Wandel, Amri
(Stanford University CA; Weizmann Institute of Science, Rehovot, Israel)
Urry, C. Megan
(Space Telescope Science Institute Baltimore, MD, United States)
Date Acquired
August 15, 2013
Publication Date
January 20, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 367
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A21758
Funding Number(s)
CONTRACT_GRANT: NAG5-1034
Distribution Limits
Public
Copyright
Other

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