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Periodic structure in the Mpc-scale jet of PKS 0637-752

Godfrey, L. E. H. and Lovell, J. E. J. and Burke-Spolaor, S. and Ekers, R. and Bicknell, G. V. and Birkinshaw, M. and Worrall, D. M. and Jauncey, D. L. and Schwartz, D. A. and Marshall, H. L. and Gelbord, J. and Perlman, E. S. (2012) Periodic structure in the Mpc-scale jet of PKS 0637-752. Astrophysical Journal Letters, 758 (2). L27. ISSN 2041-8205.

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We present 18 GHz Australia Telescope Compact Array imaging of the Mpc-scale quasar jet PKS 0637-752 with angular resolution ~0.58 arcseconds. We draw attention to a spectacular train of quasi-periodic knots along the inner 11 arcseconds of the jet, with average separation ~1.1 arcsec (7.6 kpc 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 Q ~ 10^{46} erg/s, 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 10^3 yr < \tau < 3 x 10^5 yr. The lower end of this range is applicable if the jet remains highly relativistic on kpc-scales, as implied by the IC/CMB model of jet X-ray emission. We suggest that the quasi-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 behaviour 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 < a < 30 pc, which corresponds to a maximum angular separation of ~0.1 - 5 mas.

Item Type:Article
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URLURL TypeDescription Paper
Burke-Spolaor, S.0000-0003-4052-7838
Additional Information:© 2013 IOP Publishing. Received 2012 July 23, accepted for publication 2012 September 17. The Australia Telescope Compact Array is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. DAS is supported by NASA contract NAS8-03060 and CXC grant GO9-0121B. A portion of research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Funding AgencyGrant Number
Commonwealth of AustraliaUNSPECIFIED
Non-Subject Keywords:galaxies: jets; quasars
Issue or Number:2
Record Number:CaltechAUTHORS:20130214-090237479
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Official Citation:Periodic Structure in the Megaparsec-scale Jet of PKS 0637–752 L. E. H. Godfrey et al. 2012 ApJ 758 L27
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36913
Deposited By: JoAnn Boyd
Deposited On:20 Feb 2013 20:25
Last Modified:22 Jun 2021 17:31

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