Probing the Inner Jet of the Quasar PKS 1510–089 With Multi-Waveband Monitoring During Strong Gamma-Ray Activity

Abstract

We present results from monitoring the multi-waveband flux, linear polarization, and parsec-scale structure of the quasar PKS 1510−089, concentrating on -2eight major γ-ray flares that occurred during the interval 2009.0-2009.5. The γ-ray peaks were essentially simultaneous with maxima at optical wavelengths, although the flux ratio of the two wavebands varied by an order of magnitude. The optical polarization vector rotated by 720 • during a 5-day period encompassing six of these flares. This culminated in a very bright, ∼ 1 day, optical and γ-ray flare as a bright knot of emission passed through the highest-intensity, stationary feature (the "core") seen in 43 GHz Very Long Baseline Array images. The knot continued to propagate down the jet at an apparent speed of 22c and emit strongly at γ-ray energies as a months-long X-ray/radio outburst intensified. We interpret these events as the result of the knot following a spiral path through a mainly toroidal magnetic field pattern in the acceleration and collimation zone of the jet, after which it passes through a standing shock in the 43 GHz core and then continues downstream. In this picture, the rapid γ-ray flares result from scattering of infrared seed photons from a relatively slow sheath of the jet as well as from optical synchrotron radiation in the faster spine. The 2006-2009.7 radio and X-ray flux variations are correlated at very high significance; we conclude that the X-rays are mainly from inverse Compton scattering of infrared seed photons by 20-40 MeV electrons.

Search for the shortest variability at gamma rays in flat-spectrum radio quasars

“…On one side, there is a group of researchers supporting the hypothesis that the γ rays in the sources powered by the EC process are generated by the interaction with seed photons from the molecular torus (infrared photons), which is placed at some parsecs from the central engine (e.g. Abdo et al 2010c;Marscher et al 2008Marscher et al , 2010Sikora et al 2009). On the other side, another group of researchers is instead favoringwith different arguments -the hypothesis of a dissipation inside the BLR, i.e.…”

Another look at the BL Lacertae flux and spectral variability

“…Our "geometrical" interpretation does not require these externalCompton emission components, which are not expected to contribute if the jet emission regions are parsecs away from the central black hole (see e.g. Sikora et al 2008;Marscher et al 2010;Abdo et al 2010b). …”

Optical Polarimetry and Radio Observations of PKS1510-089 between 2009 and 2013

“…The 2009 long term PA rotation event was monitored by different authors [9][10][11]13,18]. We could minimize the gaps between the observation and assume that the angle rotated by the smallest difference, as we shown in a schematic view in Figure 3.…”

“…On the polarimetric monitoring programs, several authors reported high variability on the polarization angle (PA) simultaneous to the 2009 high energy flares; however, the rotation sense of each episode is still under debate, which affects the interpretation of how much PA really changed during the flare events [9][10][11].…”