Multiepoch Very Long Baseline Array Observations of EGRET-detected Quasars and BL Lacertae Objects: Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars
Abstract
We examine the coincidence of times of high γ-ray flux and ejections of superluminal components from the core in EGRET blazars based on a Very Long Baseline Array (VLBA) monitoring program at 22 and 43 GHz from 1993 November to 1997 July. In 23 cases of γ-ray flares for which sufficient VLBA data exist, 10 of the flares (in eight objects) fall within 1 σ 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 γ-ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations that show that if the number of coincidences is >=10, the radio and γ-ray events are associated with each other at greater than 99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the γ-ray flares suggests that the γ-ray events occur in the superluminal radio knots. This implies that the γ-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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2001
- DOI:
- 10.1086/321605
- arXiv:
- arXiv:astro-ph/0102012
- Bibcode:
- 2001ApJ...556..738J
- Keywords:
-
- Galaxies: BL Lacertae Objects: General;
- Galaxies: Jets;
- Gamma Rays: Observations;
- Galaxies: Quasars: General;
- Radio Continuum: Galaxies;
- Astrophysics
- E-Print:
- 23 pages, 3 tables, 5 figures, submitted to ApJ