Multi-wavelength study of blazar 4C +01.02 during its long-term flaring activity in 2014-2017

TL;DR

This study presents a comprehensive multi-wavelength analysis of blazar 4C +01.02 during its 2014-2017 flaring period, revealing detailed flux variability, spectral behavior, and physical emission mechanisms through extensive observational data and modeling.

Contribution

It provides the first detailed broadband spectral analysis of 4C +01.02 during its flaring activity, using a single-zone leptonic model to explain flux variations and emission processes.

Findings

Detected 14 gamma-ray peaks with flux up to 61 times quiescent level.

Shortest gamma-ray variability of approximately 0.66 days.

Broadband SED modeled successfully with synchrotron, SSC, and EC processes.

Abstract

We conducted a detailed long-term spectral and temporal study of flat spectrum radio quasar 4C +01.02, by using the multi-wavelength observations from Fermi-LAT, Swift-XRT, and Swift-UVOT. The $2$-day bin $\gamma$-ray lightcurve in the 2014-2017 active state displays $14$ peak structures with a maximum integral flux $(\rm E > 100 \ MeV)$ of $\rm (2.5 \pm 0.2) \times 10^{-6}\ ph\ cm^{-2}\ s^{-1}$ at MJD 57579.1, which is approximately $61$ times higher than the base flux of $\rm (4.1 \pm 0.3) \times 10^{-8}\ ph\ cm^{-2}\ s^{-1}$, calculated by averaging the flux points when the source was in quiescent state. The shortest $\gamma$-ray variability of $0.66 \pm 0.08$ days is observed for the source. The correlation study between $\gamma$-ray spectral index and flux suggests that the source deviates from the usual trend of harder when brighter feature shown by blazars. To understand the likely physical scenario responsible for the flux variation, we performed a detailed broadband spectral analysis of the source by selecting different flux states from the multi-wavelength lightcurve. A single zone leptonic model was able to reproduce the broadband spectral energy distribution (SED) of each state. The parameters of the model in each flux state are determined using a $\chi^2$ fit. We observed that the synchrotron, synchrotron-self-Compton (SSC), and External-Compton (EC) processes produce the broadband SED under varied flux states. The adjoining contribution of the seed photons from the broad-line region (BLR) and the IR torus for the EC process are required to provide adequate fits to the GeV spectrum in all the chosen states.