MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VI. Kinematics Analysis of a Complete Sample of Blazar Jets
We discuss the jet kinematics of a complete flux-density-limited sample of 135 radio-loud active galactic nuclei (AGNs) resulting from a 13 year program to investigate the structure and evolution of parsec-scale jet phenomena. Our analysis is based on new 2 cm Very Long Baseline Array (VLBA) images obtained between 2002 and 2007, but includes our previously published observations made at the same wavelength, and is supplemented by VLBA archive data. In all, we have used 2424 images spanning the years 1994-2007 to study and determine the motions of 526 separate jet features in 127 jets. The data quality and temporal coverage (a median of 15 epochs per source) of this complete AGN jet sample represent a significant advance over previous kinematics surveys. In all but five AGNs, the jets appear one-sided, most likely the result of differential Doppler boosting. In general, the observed motions are directed along the jet ridge line, outward from the optically thick core feature. We directly observe changes in speed and/or direction in one third of the well-sampled jet components in our survey. While there is some spread in the apparent speeds of separate features within an individual jet, the dispersion is about three times smaller than the overall dispersion of speeds among all jets. This supports the idea that there is a characteristic flow that describes each jet, which we have characterized by the fastest observed component speed. The observed maximum speed distribution is peaked at ~10c, with a tail that extends out to ~50c. This requires a distribution of intrinsic Lorentz factors in the parent population that range up to ~50. We also note the presence of some rare low-pattern speeds or even stationary features in otherwise rapidly flowing jets that may be the result of standing re-collimation shocks, and/or a complex geometry and highly favorable Doppler factor.
Additional Information© 2009 American Astronomical Society. Print publication: Issue 6 (2009 December); received 2009 July 28; accepted for publication 2009 September 27; published 2009 November 5. The authors acknowledge the contributions of additional members of the MOJAVE team: Hugh Aller, Margo Aller, Ivan Agudo, Andrei Lobanov, Alexander Pushkarev, Kirill Sokolovsky, and Rene Vermeulen. Several students also contributed to this work: Christian Fromm at MPIfR, and Amy Lankey,Kevin O'Brien, BenMohlie, and Nick Mellott at Purdue University. M.L.L. has been supported under NSF grants AST-0406923 & AST-0807860, NASA-Fermi grant NNX08AV67G, and a grant from the Purdue Research Foundation. D.C.H. is supported by NSF grant AST-0707693. T.S. has been supported in part by the Academy of Finland grant 120516. M.K. has been supported in part by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. Part of this work was done by Y.Y.K. and T.S. during their Alexander von Humboldt fellowships at the MPIfR. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research has made use of NASA's Astrophysics Data System, and the NASA/IPAC Extragalactic Database (NED). The latter is operated by the Jet Propulsion Laboratory, California Institute ofTechnology, under contract with the National Aeronautics and Space Administration. Facilities: VLBA ()
ErrataM. L. Lister et al 2016 The Astronomical Journal 151 132
Published - Lister2009p6478Astron_J.pdf
Erratum - aj_151_5_132.pdf