Flaring Behavior of the Quasar 3c 454.3 Across the Electromagnetic Spectrum

Abstract

We analyze the behavior of the parsec-scale jet of the quasar 3C 454.3 during pronounced flaring activity in [2005][2006][2007][2008]. Three major disturbances propagated down the jet along different trajectories with Lorentz factors Γ >10. The disturbances show a . High-amplitude optical events in the R-band light curve precede peaks of the millimeter-wave outbursts by 15-50 days. Each optical outburst is accompanied by an increase in X-ray activity. We associate the optical outbursts with propagation of the superluminal knots and derive the location of sites of energy dissipation in the form of radiation. The most prominent and long-lasting of these, in 2005 May, occurred closer to the black hole, while the outbursts with a shorter duration in 2005 Autumn and in 2007 might be connected with the passage of a disturbance through the millimeter-wave core of the jet. The optical outbursts, which coincide with the passage of superluminal radio knots through the core, are accompanied by systematic rotation of the position angle of optical linear polarization. Such rotation appears to be a common feature during the early stages of flares in blazars. We find correlations between optical variations and those at X-ray and γ-ray energies. We conclude that the emergence of a superluminal knot from the core yields a series of optical and high-energy outbursts, and that the mm-wave core lies at the end of the jet's acceleration and collimation zone. We infer that the X-ray emission is produced via inverse Compton scattering by relativistic electrons of photons both from within the jet (synchrotron self-Compton) and external to the jet (external Compton, or EC); which one dominates depends on the physical parameters of the jet. A broken power-law model of the γ-ray spectrum reflects a steepening of the synchrotron emission spectrum from near-IR to soft UV wavelengths. We propose that the γ-ray emission is dominated by the EC mechanism, with the sheath of the jet supplying seed photons for γ-ray events that occur near the mm-wave core.

The long-term millimeter activity of active galactic nuclei

“…This changed dramatically in 2005 when the first of at least three major outbursts occured, peaking at flux densities of ≈35−40 Jy. The series of adjacent outbursts has continued until the present day, making 3C 454.3 one of the brightest extragalactic mm/radio sources currently observed (see also, e.g., Jorstad et al 2010). All outbursts show short exponential rise and decay times in the range ≈0.1−0.5 years.…”

Core shift effect in blazars

“…In addition, we adopted θ = 5 • .2, φ = 1 • .6, δ = 10.9, z = 0.30 and DL = 1.60 Mpc for S5 0716+714; θ = 2 • .4, φ = 0 • .4, δ = 24.1, z = 0.536 and DL = 3.08 Gpc for 3C 279; and θ = 7 • .7, φ = 1 • .9, δ = 7.2, z = 0.069 and D = 3.07 Gpc for BL Lacertae (Jorstad et al 2010;Pushkarev et al 2009;Algaba, Gabuzda, & Smith 2012). The core position offset (Ωrν) for S5 0716+714 is 19.81 ± 10.49 pcGHz; for Segment 1 of 3C 279 is 6.69±2.77 pcGHz and for Segment 2 is 8.24±2.93 pcGHz; for BL Lacertae, Mutel et al (1990) measured an Ωrν of 3.7 pcGHz based on 5.0 and 10.6 GHz observations while O'Sullivan & Gabuzda (2009) measured an Ωrν of 3.4 ± 0.3 pcGHz.…”

MULTIWAVELENGTH STUDY OF QUIESCENT STATES OF Mrk 421 WITH UNPRECEDENTED HARD X-RAY COVERAGE PROVIDED BY NuSTAR IN 2013

“…The effective wavelength of this bandpass is not too different from the Kron-Cousins R band, and the wavelength dependence in the polarization of Mrk 421 seen in the spectropolarimetry during this period is not strong enough to significantly affect the variability analysis of the measurements from various telescopes. The observing and data-processing procedures for the polarization measurements are described in Larionov et al (2008), Smith et al (2009), andJorstad et al (2010).…”