paper

Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects: Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars

arXiv:astro-ph/0102012 · doi:10.1086/321605

Abstract

We examine the coincidence of times of high -ray flux and ejections of superluminal components from the core in EGRET blazars based on a VLBA monitoring program at 22 and 43 GHz from November 1993 to July 1997. In 23 cases of -ray flares for which sufficient VLBA data exist, 10 of the flares (in 8 objects) fall within 1 uncertainties of the extrapolated epoch of zero separation from the core of a superluminal radio component. In each of two sources (0528+134 and 1730-130) two successive -ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations which show that if the number of coincidences 10 the radio and -ray events are associated with each other at >99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the -ray flares suggests that the -ray events occur in the superluminal radio knots. This implies that the -ray flares are caused by inverse Compton scattering by relativistic electrons in the parsec-scale regions of the jet rather than closer to the central engine.

23 pages, 3 tables, 5 figures, submitted to ApJ

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