Multifrequency spectra of BL Lac objectsA program to obtain simultaneous multifrequency spectra of BL Lacertae objects that are known X-ray sources is discussed. The IUE spectra are generally featureless and well-fitted by power law models. For the faintest exposures, Gaussian extraction of the spectrum can greatly impove the signal-to-noise. Most program objects vary in the ultraviolet, although the time scales are not known because of limited observing time. The broadband spectra of BL Lacs exhibit a range of characteristics but the curvature is always downward and the shape is generally smooth. This can be interpreted as synchrotron emission from a relativistic jet; different jet models are possible, and each allows a range of values for the bulk velocity, magnetic field strength, and electron density. Synchrotron models are not required, however an accretion disk model also gives a good fit to the ultraviolet-through-X-ray continuum.
Document ID
19890007221
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Urry, C. M. (Space Telescope Science Inst. Baltimore, MD., United States)
Kondo, Y. (NASA Goddard Space Flight Center Greenbelt, MD., United States)
Mufson, S. L. (Indiana Univ. Bloomington., United States)
Wandel, A. (Stanford Univ. CA., United States)
Date Acquired
September 5, 2013
Publication Date
June 1, 1988
Publication Information
Publication: ESA, Proceedings of the Celebratory Symposium on a Decade of UV Astronomy with the IUE Satellite, Volume 2