Bibcode
DOI
Worrall, D. M.; Rodriguez-Espinosa, J. M.; Puschell, J. J.; Bruhweiler, F. C.; Miller, H. R.; Aller, M. F.; Aller, H. D.
Bibliographical reference
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 286, Nov. 15, 1984, p. 711-717. Research supported by Georgia State University.
Advertised on:
11
1984
Journal
Citations
25
Refereed citations
23
Description
Single-epoch multifrequency data for the BL Lac objects OI 90.4 and 3C
66A, spanning radio through ultraviolet wavelengths, are presented, as
well as other measurements relevant to intensity and spectral-shape
variability. Both BL Lac objects exhibit spectral curvature in the
infrared-to-ultraviolet region, a properity that is inferred to be usual
for this object class. Variability in the ultraviolet spectral index of
OI 90.4 is found, whereas the spectral index of 3C 66A is the same in
two observations 17 months apart. A synchrotron self-Compton jet model
is applied to each BL Lac object. The OI 90.4 data are found to be best
satisfied by a jet with a relatively high degree of relativistic
beaming, but emission at frequencies below about 50 GHz is not described
by the model. Furthermore, 3C 66A may not always undergo strong
relativistic beaming, and the model may incorporate the small fraction
of the total radio emission below about 20 GHz that is from within about
1.5 milliarcsec of the core.