Journal Article

TeV blazar variability: the firehose instability?

Prasad Subramanian, Amit Shukla and Peter A. Becker

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 2, pages 1707-1710
Published in print June 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20991.x
TeV blazar variability: the firehose instability?

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Recently observed minute-time-scale variability of blazar emission at TeV energies has imposed severe constraints on jet models and TeV emission mechanisms. We focus on a robust jet instability to explain this variability. As a consequence of the bulk outflow of the jet plasma, the pressure is likely to be anisotropic, with the parallel pressure P|| in the forward jet direction exceeding the perpendicular pressure P. Under these circumstances, the jet is susceptible to the firehose instability, which can cause disruptions in the large-scale jet structure and result in variability of the observed radiation. For a realistic range of parameters, we find that the growth time-scale of the firehose instability is ≈ a few minutes, in good agreement with the observed TeV variability time-scales for Mrk 501 and PKS 2155−304.

Keywords: black hole physics; instabilities; plasmas; galaxies: jets; gamma-rays: galaxies

Journal Article.  3136 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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