Geodetic VLBI Observations of EGRET Blazars

Piner, B. G.; Kingham, K. A.

doi:10.1086/306346

Cited by 21 publications

(19 citation statements)

References 52 publications

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“…The very weak south-western extension of A could be related to the faint intermediate component in Kellermann et al (1998) and component C in Pyatunina et al (2000). Compared with the 2 GHz data of Piner et al (1998), with a resolution similar to ours, the separation we measure at 8.4 GHz between A and D strengthens its constancy over a time baseline of ten years, giving a proper motion of 0.02 ± 0.03 mas/yr, corresponding to β app ≈ 0.3±0.44. Furthermore, our 15 GHz image shows a separation between A and the bright features D1 and D2 equal to that reported by Kellermann et al (2004) at the same frequency over a six-year interval, confirming that no apparent motion is present.…”

Section: +149supporting

confidence: 81%

“…Although the authors described the source as a core-jet we thought that it could be an asymmetric double with a weak core and therefore worth observing again. Additional images at 2.3 and 8.5 GHz from geodetic VLBI observations (Piner & Kingham 1998; Pyatunina et al 2000) and from VLBA observations at 15, 22 GHz (Wiik et al 2001) and 43 GHz (Pyatunina et al 2000) are also available. From these images our component A turned out to have a rather complex structure, being resolved into a bright component (called A in Pyatunina et al 2000) plus two weaker ones (B and C in Pyatunina et al 2000), which show activity and possibly superluminal motions.…”

Section: +149mentioning

confidence: 99%

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Multi-frequency VLBA observations of compact sources from the Peacock and Wall catalogue

Rossetti¹,

Mantovani²,

Dallacasa

et al. 2005

A&A

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Abstract. VLBA observations are presented for 6 compact radio sources selected from the Peacock & Wall catalogue. From the new morphological and spectral information, 2 objects that in the Peacock and Wall catalogue are flat spectrum (α ≤ 0.5) sources, appear to be double sided objects with linear sizes of the order of one kpc. Three are core-jet sources and the last one is still an "enigmatic" object. These data complete the sample of small double compact sources in the Peacock & Wall catalogue and the complete list is given.

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Section: +149supporting

confidence: 81%

Section: +149mentioning

confidence: 99%

Multi-frequency VLBA observations of compact sources from the Peacock and Wall catalogue

Rossetti¹,

Mantovani²,

Dallacasa

et al. 2005

A&A

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“…Figure 18 shows that the components move along curved path. For comparison, we also included the data from the geodetic VLBI observation by Piner & Kingham (1998) (estimates from their Fig. 10) during period from 1988 to 1996 in Fig.…”

Section: A Helical Patternmentioning

confidence: 99%

A relativistic helical jet in theγ-ray AGN 1156+295

Hong

Dong

Gurvits

et al. 2004

A&A

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Abstract. We present the results of a number of high resolution radio observations of the AGN 1156+295. These include multi-epoch and multi-frequency VLBI, VSOP, MERLIN and VLA observations made over a period of 50 months. The 5 GHz MERLIN images trace a straight jet extending to ∼2 at PA ∼ −18• . Extended low brightness emission was detected in the MERLIN observation at 1.6 GHz and the VLA observation at 8.5 GHz with a bend of ∼90• at the end of the 2 arcsec jet. A region of similar diffuse emission is also seen about 2 arcsec south of the radio core. The VLBI images of the blazar reveal a core-jet structure with an oscillating jet on a milli-arcsecond (mas) scale which aligns with the arcsecond jet at a distance of several tens of milli-arcseconds from the core. This probably indicates that the orientation of the jet structure is close to the line of sight, with the northern jet being relativistically beamed toward us. In this scenario the diffuse emission to the north and south is not beamed and appears symmetrical. For the northern jet at the mas scale, proper motions of 13.7 ± 3.5, 10.6 ± 2.8, and 11.8 ± 2.8 c are measured in three distinct components of the jet (q 0 = 0.5, H 0 = 65 km s −1 Mpc −1 are used through out this paper). Highly polarised emission is detected on VLBI scales in the region in which the jet bends sharply to the north-west. The spectral index distribution of the source shows that the strongest compact component has a flat spectrum, and the extended jet has a steep spectrum. A helical trajectory along the surface of a cone was proposed based on the conservation laws for kinetic energy and momentum to explain the observed phenomena, which is in a good agreement with the observed results on scales of 1 mas to 1 arcsec.

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“…The parsec-scale core was identified by Kovalev et al (2009) ;Pushkarev et al (2010) as a likely location for both the γ-ray and radio flares, which appears within typical timescales of up to a few months of each other. Many γ-ray flares are connected with the ejection of a newly born components (e.g., Jorstad et al 2001;Agudo et al 2011) but sometimes no observed components can be associated with the γ-ray flares (e.g., Piner & Kingham 1998), though many sources show dual properties (e.g., Marscher et al 2008;Ramakrishnan et al 2014;Morozova et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength observations of the γ-ray flaring quasar S4 1030+61 in 2009–2014

Kravchenko

Kovalev

Hovatta

2016

Mon. Not. R. Astron. Soc.

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We present a study of the parsec-scale multi-frequency properties of the quasar S4 1030+61 during a prolonged radio and γ-ray activity. Observations were performed within Fermi γ-ray telescope, OVRO 40-m telescope and MOJAVE VLBA monitoring programs, covering five years from 2009. The data are supplemented by four-epoch VLBA observations at 5, 8, 15, 24, and 43 GHz, which were triggered by the bright γ-ray flare, registered in the quasar in 2010. The S4 1030+61 jet exhibits an apparent superluminal velocity of (6.4±0.4)c and does not show ejections of new components in the observed period, while decomposition of the radio light curve reveals nine prominent flares. The measured variability parameters of the source show values typical for Fermi-detected quasars. Combined analysis of radio and γ-ray emission implies a spatial separation between emitting regions at these bands of about 12 pc and locates the γ-ray emission within a parsec from the central engine. We detected changes in the value and direction of the linear polarization and the Faraday rotation measure. The value of the intrinsic brightness temperature of the core is above the equipartition state, while its value as a function of distance from the core is well approximated by the power-law. Altogether these results show that the radio flaring activity of the quasar is accompanied by injection of relativistic particles and energy losses at the jet base, while S4 1030+61 has a stable, straight jet well described by standard conical jet theories.

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Geodetic VLBI Observations of EGRET Blazars

Cited by 21 publications

References 52 publications

Multi-frequency VLBA observations of compact sources from the Peacock and Wall catalogue

Multi-frequency VLBA observations of compact sources from the Peacock and Wall catalogue

A relativistic helical jet in theγ-ray AGN 1156+295

Multiwavelength observations of the γ-ray flaring quasar S4 1030+61 in 2009–2014

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