Parsec‐Scale Blazar Monitoring: Proper Motions

Homan, D. C.; Ojha, R.; Wardle, J. F. C.; Roberts, D. H.; Aller, M. F.; Aller, H. D.; Hughes, P. A.

doi:10.1086/319466

Cited by 135 publications

(158 citation statements)

References 40 publications

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“…Comparing that to our integrated flux of 0.13 Jy at 1.7 GHz, we find the spectral index to indeed be ¼ À0:6 AE 0:1 over more than a decade in frequency. At À0.6, the spectral index of the feature is less steep than the milliarcsecond scale jet for which Homan et al (2002) find ¼ À0:9 AE 0:1 from multi-epoch VLBA observations at 15 and 22 GHz. Fitting simple models to our 1.7 and 5 GHz data, we find a spectral index farther out (R $ 20 30 mas) in the milliarcsecond jet of ¼ À0:8 AE 0:1.…”

Section: The Feature At 0>3mentioning

confidence: 84%

“…For the purposes of this discussion we take this alignment angle, VLBA , to be 3 , which is the optimum angle for the superluminal motion of 20c observed by Homan et al (2001).…”

Section: Head-on View Of Pks 1510à089mentioning

confidence: 99%

“…More recent Very Long Baseline Array (VLBA) observations ranging from 2 GHz up to 43 GHz (Fey & Charlot 1997;Kellermann et al 1998;Homan et al 2001;Jorstad et al 2001;J. Wardle et al 2002, in preparation) show the jet extending up to 40 mas (at 2 GHz) to the north-northwest, directly toward the '' counterfeature '' at 0>3 observed by O'Dea et al (1988).…”

Section: Introductionmentioning

confidence: 99%

“…PKS 1510À089 has been detected in gamma rays by EGRET (Hartman et al 1999) and exhibits apparent jet motions in excess of 20 times the speed of light (Homan et al 2001;J. Wardle et al 2002, in preparation).…”

Section: Introductionmentioning

confidence: 99%

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PKS 1510−089: A Head‐on View of a Relativistic Jet

Homan¹,

Wardle²,

Cheung³

et al. 2002

ApJ

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The gamma-ray blazar PKS 1510À089 has a highly superluminal milliarcsecond jet at a position angle (P.A.) of À28 and an arcsecond jet with an initial P.A. of 155 . With a DP.A. of 177 between the arcsecond and milliarcsecond jets, PKS 1510À089 is perhaps the most highly misaligned radio jet ever observed and serves as a graphic example of projection effects in a highly beamed relativistic jet. Here we present the results of observations designed to bridge the gap between the milliarcsecond and arcsecond scales. We find that a previously detected '' counterfeature '' to the arcsecond jet is directly fed by the milliarcsecond jet. This feature is located 0>3 from the core, corresponding to a deprojected distance of 30 kpc. The feature appears to be dominated by shocked emission and has an almost perfectly ordered magnetic field along its outside edge. We conclude that it is most likely a shocked bend, viewed end-on, where the jet crosses our line of sight to form the southern arcsecond jet. While the bend appears to be nearly 180 when viewed in projection, we estimate the intrinsic bending angle to be between 12 and 24 . The cause of the bend is uncertain; however, we favor a scenario where the jet is bent after it departs the galaxy, either by ram pressure due to winds in the intracluster medium or simply by the density gradient in the transition to the intergalactic medium.

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Section: The Feature At 0>3mentioning

confidence: 84%

“…For the purposes of this discussion we take this alignment angle, VLBA , to be 3 , which is the optimum angle for the superluminal motion of 20c observed by Homan et al (2001).…”

Section: Head-on View Of Pks 1510à089mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PKS 1510−089: A Head‐on View of a Relativistic Jet

Homan¹,

Wardle²,

Cheung³

et al. 2002

ApJ

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“…Part of these data have been used to investigate the statistical properties of a sample of active galaxies (Homan et al 2001;Lister et al 2009b). Moreover, Iguchi et al (2000) made observations of this source at four frequencies including 15 GHz with the VLBA in 1998, which we recalibrated and re-mapped.…”

Section: Observations and Data Analysismentioning

confidence: 99%

The parsec-scale jet of PKS 1749+096

Shen

Krichbaum

et al. 2012

A&A

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Context. PKS 1749+096 is a BL Lac object showing weak extended jet emission to the northeast of the compact VLBI core on parsec scales. Aims. We aim at better understanding the jet kinematics and variability of this source and finding clues that may applicable to other BL Lac objects. Methods. The jet was studied with multi-epoch multi-frequency high-resolution VLBI observations. Results. The jet is characterized by a one-sided curved morphology at all epochs and all frequencies. The VLBI core, located at the southern end of the jet, was identified based on its spectral properties. The equipartition magnetic field of the core was investigated, through which we derived a Doppler factor of 5, largely consistent with that derived from kinematics (component C5). The study of the detailed jet kinematics at 22 and 15 GHz, spanning a period of more than 10 years, indicates the possible existence of a bimodal distribution of the jet apparent speed. Ballistic and non-ballistic components are found to coexist in the jet. Superluminal motions in the range of 5-21 c were measured in 11 distinct components. We estimated the physical jet parameters with the minimum Lorentz factor of 10.2 and Doppler factors in the range of 10.2-20.4 (component C5). The coincidence in time of the component's ejection and flares supports the idea that, at least in PKS 1749+096, ejection of new jet components is connected with major outbursts in flux density. For the best-traced component (C5) we found that the flux density decays rapidly as it travels downstream the jet, accompanied by a steepening of its spectra, which argues in favor of a contribution of inverse Compton cooling. These properties make PKS 1749+096 a suitable target for an intensive monitoring to decipher the variability phenomenon of BL Lac objects.

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The X‐ray and radio jets of quasars on kiloparsec scales

Jorstad¹,

Marscher

2006

Astron Nachr

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Abstract.We have observed five quasars (0827+243, 0923+392, 1222+216, 1317+520, and 2209+080) with Chandra at 0.2-8 keV and with the VLA at 5 and 15 GHz. The X-ray emission is detected from all the radio jets except for 0923+392, whose double radio jet only extends out to the edge of the X-ray PSF. We model the spectral energy distribution of the jet features assuming that the X-ray emission originates via inverse Compton scattering off the cosmic microwave background by relativistic electrons. For two sources (0827+243 and 1222+216) proper motion on parsec scales is consistent with the Doppler factors derived from the model, which implies that no deceleration occurs between parsec and kiloparsec jets.

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Parsec‐Scale Blazar Monitoring: Proper Motions

Cited by 135 publications

References 40 publications

PKS 1510−089: A Head‐on View of a Relativistic Jet

PKS 1510−089: A Head‐on View of a Relativistic Jet

The parsec-scale jet of PKS 1749+096

The X‐ray and radio jets of quasars on kiloparsec scales

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