Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz during 10 yr of the VLBA-BU-BLAZAR Program

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2022
Major/Subject
Mcode
Degree programme
Language
en
Pages
42
Series
Astrophysical Journal, Supplement Series, Volume 260, issue 1
Abstract
We analyze the parsec-scale jet kinematics from 2007 June to 2018 December of a sample of γ-ray bright blazars monitored roughly monthly with the Very Long Baseline Array (VLBA) at 43 GHz under the VLBA-BU-BLAZAR program. We implement a novel piecewise linear fitting method to derive the kinematics of 521 distinct emission knots from a total of 3705 total intensity images in 22 quasars, 13 BL Lacertae objects, and 3 radio galaxies. Apparent speeds of these components range from 0.01c to 78c, and 18.6% of knots (other than the "core") are quasi-stationary. One-fifth of moving knots exhibit nonballistic motion, with acceleration along the jet within 5 pc of the core (projected) and deceleration farther out. These accelerations occur mainly at locations coincident with quasi-stationary features. We calculate the physical parameters of 273 knots with statistically significant motion, including their Doppler factors, Lorentz factors, and viewing angles. We determine the typical values of these parameters for each jet and the average for each subclass of active galactic nuclei. We investigate the variability of the position angle of each jet over the 10 yr of monitoring. The fluctuations in position of the quasi-stationary components in radio galaxies tend to be parallel to the jet, while no directional preference is seen in the components of quasars and BL Lacertae objects. We find a connection between γ-ray states of blazars and their parsec-scale jet properties, with blazars with brighter 43 GHz cores typically reaching higher γ-ray maxima during flares.
Description
Funding Information: We thank the anonymous referee for comprehensive and constructive feedback that greatly improved this paper. The research at Boston University was supported in part by NASA grants 80NSSC17K0649, 80NSSC20K1567, and 80NSSC20K1566 (Fermi Guest Investigator Program), the NRAO Student Observing Support Program, and Massachusetts Space grant 316080. I.A. acknowledges financial support from the Spanish “Ministerio de Ciencia e Innovación” (MCINN) through grants AYA2016-80889-P and PID2019-107847RB-C44, and through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). The VLBA is an instrument of the National Radio Astronomy Observatory. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated by Associated Universities, Inc. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The optical data used in this work were obtained using the 1.8 m Perkins Telescope Observatory in Flagstaff, Arizona, USA, which is owned and operated by Boston University. This publication makes use of data obtained at the Metsähovi Radio Observatory, operated by Aalto University in Finland. This research made use of Astropy, 17 Publisher Copyright: © 2022. The Author(s). Published by the American Astronomical Society.
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Citation
Weaver , Z R , Jorstad , S G , Marscher , A P , Morozova , D A , Troitsky , I S , Agudo , I , Gómez , J L , Lähteenmäki , A , Tammi , J & Tornikoski , M 2022 , ' Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz during 10 yr of the VLBA-BU-BLAZAR Program ' , Astrophysical Journal, Supplement Series , vol. 260 , no. 1 , 12 . https://doi.org/10.3847/1538-4365/ac589c