1 research outputs found
The June 2016 Optical and Gamma-Ray Outburst and Optical Micro-Variability of the Blazar 3C454.3
The quasar 3C454.3 underwent a uniquely-structured multi-frequency outburst
in June 2016. The blazar was observed in the optical band by several
ground-based telescopes in photometric and polarimetric modes, at -ray
frequencies by the \emph{Fermi}\ Large Area Telescope, and at 43 GHz with the
Very Long Baseline Array. The maximum flux density was observed on 2016 June 24
at both optical and -ray frequencies, reaching
mJy and ph cm s, respectively. The June 2016
outburst possessed a precipitous decay at both -ray and optical
frequencies, with the source decreasing in flux density by a factor of 4 over a
24-hour period in band. Intraday variability was observed throughout the
outburst, with flux density changes between 1 and 5 mJy over the course of a
night. The precipitous decay featured statistically significant quasi-periodic
micro-variability oscillations with an amplitude of - about the
mean trend and a characteristic period of 36 minutes. The optical degree of
polarization jumped from to nearly 20\% during the outburst, while
the position angle varied by \sim120\degr. A knot was ejected from the 43 GHz
core on 2016 Feb 25, moving at an apparent speed .
From the observed minimum timescale of variability
hr and derived Doppler factor
, we find a size of the emission region
cm. If the quasi-periodic micro-variability
oscillations are caused by periodic variations of the Doppler factor of
emission from a turbulent vortex, we derive a rotational speed of the vortex
.Comment: 19 pages, 13 figures, 3 tables, accepted to the Astrophysical Journal
2019 March