Fermi Gamma-ray Space Telescope

"GRB-like" emission in the TeV-detected AGN 3C 84. A solution to the "Doppler crisis"?

Jeffrey Hodgson
(Bindu Rani, Junghwan Oh, Alan Marscher, Svetlana Jorstad, Sang-Sung Lee, Sascha Trippe, Florent Mertens, Yosuke Mizuno)


We have performed a high cadence, high resolution and multi-frequency analysis of the relatively low Doppler boosted AGN 3C 84. The source exhibits a mild "Doppler crisis" as it exhibits TeV emission, yet is not highly Doppler boosted. By combining Fermi/LAT data with multi-frequency (14, 7, 3 and 2 mm) VLBI data from the Korean VLBI Network and 7 mm VLBI data from the VLBA-BU-BLAZAR monitoring program, we found that there are at least three different modes of variability in 3C 84, with some occurring near the central black hole and some also occurring in a downstream jet feature. The kinematic analysis showed that the largest flaring occurs when mildly relativistic emission features (interpreted as shocks) "catch up" with slow moving shocks in behavior reminiscent of slow duration GRBs. We interpret the emission mechanism as due to magnetic reconnection induced mini-jets and propose the mechanism as a solution to the "Doppler crisis".