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Paper: Relationship between High-Frequency Emission and the Radio Jet in Blazars
Volume: 340, Future Directions in High Resolution Astronomy: The 10th Anniversary of the VLBA
Page: 25
Authors: Marscher, A.P.
Abstract: The combination of VLBA and X-ray/γ-ray monitoring of blazars reveals some strong connections across the electromagnetic spectrum. In 3C 279 and PKS 1510.089, the nature of the X-ray variability changes as the projected direction of the compact jet swings. Outbursts in the radio, IR, or optical precede flares at high energies, and ejections of superluminal radio knots often accompany the flares. In 3C 120, in which the X-rays probably come from a corona above an accretion disk, the emergence of superluminal radio knots follows dips in the X-ray emission, as in microquasars. The delay implies that the core seen on high-frequency VLBA images is at least 0.4 pc from the central engine. Despite the undersampling of γ-ray variations by the Compton Gamma Ray Observatory's EGRET detector, there is strong evidence that γ-ray flares occur near the beginning of radio outbursts and superluminal ejections. It therefore appears that the high-energy emission is generated in the radio jet, at or downstream of the core seen on VLBA images. The VLBA, preferably combined with a space antenna, is therefore the perfect companion to the upcoming GLAST γ-ray mission.
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