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Periodic structure in the megaparsec-scale jet of pks 0637-752

Citation

Godfrey, LEH and Lovell, JEJ and Burke-Spolaor, S and Ekers, R and Bicknell, GV and Birkinshaw, M and Worrall, DM and Jauncey, DL and Schwartz, DA and Marshall, HL and Gelbord, J and Perlman, ES and Georganopoulos, M, Periodic structure in the megaparsec-scale jet of pks 0637-752, Astrophysical Journal Letters, 758, (2) Article L27. ISSN 2041-8205 (2012) [Refereed Article]

Copyright Statement

Copyright 2012 The American Astronomical Society.

DOI: doi:10.1088/2041-8205/758/2/L27

Abstract

We present 18GHz Australia Telescope Compact Array imaging of the megaparsec-scale quasar jet PKS 0637-752 with angular resolution ~0.58". We draw attention to a spectacular train of quasi-periodic knots along the inner 11" of the jet, with average separation 1.1 arcsec (7.6kpc projected). We consider two classes of model to explain the periodic knots: those that involve a static pattern through which the jet plasma travels (e.g., stationary shocks) and those that involve modulation of the jet engine. Interpreting the knots as re-confinement shocks implies the jet kinetic power Qjet ~ 1046erg s-1, but the constant knot separation along the jet is not expected in a realistic external density profile. For models involving modulation of the jet engine, we find that the required modulation period is 2 x 103 yr < τ < 3 x 105 yr. The lower end of this range is applicable if the jet remains highly relativistic on kiloparsec scales, as implied by the IC/CMB model of jet X-ray emission. We suggest that the periodic jet structure in PKS 0637-752 may be analogous to the quasi-periodic jet modulation seen in the microquasar GRS 1915+105, believed to result from limit cycle behavior in an unstable accretion disk. If variations in the accretion rate are driven by a binary black hole, the predicted orbital radius is 0.7 pc ≲ a ≲ 30 pc, which corresponds to a maximum angular separation of ~0.1-5 mas.

Item Details

Item Type:Refereed Article
Keywords:galaxies: active; galaxies: jets; quasars: individual (PKS0637–752)
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Lovell, JEJ (Dr Jim Lovell)
ID Code:83101
Year Published:2012
Web of Science® Times Cited:15
Deposited By:Mathematics and Physics
Deposited On:2013-03-01
Last Modified:2013-07-01
Downloads:0

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