Multi-frequency VLBA study of the blazar S5 0716+714 during the active state in 2004

Abstract

We observed the blazar 0716+714 with the VLBA during its active state in [2003][2004]. In this paper we discuss multi-frequency analysis of the inner jet (first 1 mas) kinematics. The unprecedentedly dense time sampling allows us to trace jet components without misidentification and to calculate the component speeds with good accuracy. In the smooth superluminal jet we were able to identify and track three components over time moving outwards with relatively high apparent superluminal speeds (8.5-19.4 c), which contradicts the hypothesis of a stationary oscillating jet in this source. Component ejections occur at a relatively high rate (once in two months), and they are accompanied by mm-continuum outbursts. Superluminal jet components move along wiggling trajectories, which is an indication of actual helical motion. Fast proper motion and rapid decay of the components suggest that this source should be observed with the VLBI at a rate of at least once in one or two months in order to trace superluminal jet components without confusion.

Multi-frequency VLBA study of the blazar S5 0716+714 during the active state in 2004

“…Our analysis of the inner jet kinematics of 0716+714 at frequencies of 22, 43, and 86 GHz also revealed a fast-moving jet with apparent speeds from 8c to 19c on the spatial scale from 0 to 1.5 mas (Rastorgueva et al 2009). Here we present results of our short-term kinematic study at 5 GHz.…”

“…Our aim was to study the structure and kinematics of the largescale (from 1 to 12 mas) jet, and compare it with the results for the inner (<1 mas) jet, which were published in Rastorgueva et al (2009). We applied a conventional method and a GMEM to the same data set to compare their kinematic results.…”

“…The inner jet of 0716+714 is well resolved at higher (>5 GHz) frequencies and reveals a clear outward motion, although the emission fades away at about 1 mas as the spectral peak moves to lower frequencies (see Rastorgueva et al 2009). At 5 GHz, only one or two components are resolved in the inner jet region, depending on the method, and they also have a clear outward motion.…”

“…In the inner and outer parts of the jet, the Lorentz factor Γ is the same, but the other three parameters differ: Θ 2 > Θ 1 , and therefore β app 2 < β app 1 and δ 2 < δ 1 . From the 22 and 43 GHz data analysis (Rastorgueva et al 2009) we estimated the kinematic parameters for the inner jet: the maximum apparent speed is β app max = 19.4 and the corresponding minimum Lorentz factor is Γ min = 19.5. The corresponding minimum angle of the jet to the line of sight is Θ mins = 3.0 • .…”

Global alignments of parsec-scale AGN radio jets and their polarization planes

“…Because we stacked data for different epochs when available, this variability was partially averaged. Furthermore, the jet at parsec and kiloparsec scales is not always parallel (Kharb et al 2010), and moreover, even at the parsec (milliarcsecond) scale, significant jet bending is not uncommon (e.g., Rastorgueva et al 2009). In order to estimate uncertainties in the derived inner PA jet , we calculated pairwise differences of their values at separate frequencies and constructed distributions of these differences.…”