Multi-wavelength Temporal Variability of the Blazar 3C 454.3 during 2014 Activity Phase

TL;DR

This study analyzes the multi-wavelength variability of blazar 3C 454.3 during 2014, revealing changes in emission lag times and supporting a magnetic field-related origin for its high-energy emissions.

Contribution

It provides the first detailed multi-band correlation analysis of 3C 454.3 during a high activity phase, highlighting variable lag patterns and consistent emission region conditions.

Findings

Gamma-ray lags vary from no lag to ~3 days behind IR/optical.

Emission region remains localized and similar across activity states.

X-ray and gamma-ray emissions are likely inverse Comptonized IR/optical photons.

Abstract

We present a multi-wavelength temporal analysis of the blazar 3C 454.3 during the high $\gamma$-ray active period from May-December, 2014. Except for X-rays, the period is well sampled at near-infrared (NIR)-optical by the \emph{SMARTS} facility and the source is detected continuously on daily timescale in the \emph{Fermi}-LAT $\gamma$-ray band. The source exhibits diverse levels of variability with many flaring/active states in the continuously sampled $\gamma$-ray light curve which are also reflected in the NIR-optical light curves and the sparsely sampled X-ray light curve by the \emph{Swift}-XRT. Multi-band correlation analysis of this continuous segment during different activity periods shows a change of state from no lags between IR and $\gamma$-ray, optical and $\gamma$-ray, and IR and optical to a state where $\gamma$-ray lags the IR/optical by $\sim$3 days. The results are consistent with the previous studies of the same during various $\gamma$-ray flaring and active episodes of the source. This consistency, in turn, suggests an extended localized emission region with almost similar conditions during various $\gamma$-ray activity states. On the other hand, the delay of $\gamma$-ray with respect to IR/optical and a trend similar to IR/optical in X-rays along with strong broadband correlations favor magnetic field related origin with X-ray and $\gamma$-ray being inverse Comptonized of IR/optical photons and external radiation field, respectively.