Brightest Fermi-LAT Flares of PKS 1222+216: Implications on Emission and Acceleration Processes

Abstract

We present a high time resolution study of the two brightest $\gamma$-ray outbursts from a blazar PKS 1222+216 observed by the \textit{Fermi} Large Area Telescope (LAT) in 2010. The $\gamma$-ray light-curves obtained in four different energy bands: 0.1--3, 0.1--0.3, 0.3--1 and 1--3 GeV, with time bin of 6 hr, show asymmetric profiles with a similar rise time in all the bands but a rapid decline during the April flare and a gradual one during the June. The light-curves during the April flare show $\sim 2$ days long plateau in 0.1--0.3 GeV emission, erratic variations in 0.3--1 GeV emission, and a daily recurring feature in 1--3 GeV emission until the rapid rise and decline within a day. The June flare shows a monotonic rise until the peak, followed by a gradual decline powered mainly by the multi-peak 0.1--0.3 GeV emission. The peak fluxes during both the flares are similar except in the 1--3 GeV band in April which is twice the corresponding flux during the June flare. Hardness ratios during the April flare indicate spectral hardening in the rising phase followed by softening during the decay. We attribute this behavior to the development of a shock associated with an increase in acceleration efficiency followed by its decay leading to spectral softening. The June flare suggests hardening during the rise followed by a complicated energy dependent behavior during the decay. Observed features during the June flare favor multiple emission regions while the overall flaring episode can be related to jet dynamics.

17 pages, 9 figures, 4 tables, accepted for publication in ApJ

References in corpus (10)

• Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent Is the Universe?
• MAGIC discovery of VHE Emission from the FSRQ PKS 1222+21
• Implications of very rapid TeV variability in blazars
• GeV breaks in blazars as a result of gamma-ray absorption within the broad-line region
• Detection of significant cm to sub-mm band radio and gamma-ray correlated variability in Fermi bright blazars
• Fermi acceleration in astrophysical jets
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. III. Deep VLA Images at 1.4 GHz
• Improved AGN light curve analysis with the z-transformed discrete correlation function
• Multifrequency Studies of the Peculiar Quasar 4C +21.35 During the 2010 Flaring Activity
• Gamma-ray Flare of PKS 1222+216 in 2010: Effect of Jet Dynamics at the Recollimation Zone

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