University of Hertfordshire

From the same journal

From the same journal

By the same authors

  • W.K. Gear
  • Jason Stevens
  • D.H. Hughes
  • S.J. Litchfield
  • E.I. Robson
  • H. Terasranta
  • E. Valtaoja
  • H. Steppe
  • M. F. Aller
  • H. D. Aller
View graph of relations
Original languageEnglish
Pages (from-to)167-186
JournalMonthly Notices of the Royal Astronomical Society
Journal publication date1 Mar 1994
Publication statusPublished - 1 Mar 1994


We present quasi-simultaneous radio, millimetre and submillimetre spectra of 22 BL Lac objects and 24 radio-loud, violently variable quasars. These data are used to test the hypothesis that BL Lacs and OVV quasars are fundamentally different objects. We find a considerable degree of consistency of the overall spectral shape in all sources and conclude that the same basic physical model applies to the continuum emission over this frequency range in both cases. There is clear evidence in the data for the BL Lacs to have flatter 150-375 GHz spectra, and we attribute the effect to an intrinsic difference between the underlying jets in the two types of object. A similar difference in the 37-270 GHz spectral indices between the two types can be attributed to a simple redshifting of the synchrotron self-absorption turnover.

ID: 523839