Decelerating Flows in TeV Blazars: A Resolution to theBL Lacertae-FR I Unification Problem

摘要

The values of the Doppler factor 6 of the relativistic plasma out-flows responsible for the observed radiation of the TeV-detected BL Lacertae(BL) objects are obtained by fitting their spectra by the Synchrotron-Self Comp-ton (SSC) process; these model fits are driven mainly by the need to match theflux of these objects at the highest (TeV) energies and yield δ > 50, values in violent disagreement with the BL Lac/FR I unification schemes. Motivated bythe absence of any accompanying super-luminal velocities in the sub-pc scalejets of the best studied TeV blazars, MKN 421 and MKN 501, we propose thepossibility that the relativistic flows in the TeV BLs decelerate. We show thatthe SSC emission by plasma in relativistic motion with a rather modest Lorentzfactor F = 15, decelerating to values consistent with its kinematic state as in-ferred by recent radio interferometric observations can both produce good fitsto the spectra and be consistent with the BL Lac/FR I unification scheme.