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arXiv · 1901.04184

Study on Temporal and Spectral behavior of 3C 279 during 2018 January flare

Zahir Shah·V. Jithesh·S. Sahayanathan·Ranjeev Misra·Naseer Iqbal
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Abstract

We present a detailed temporal and spectral study of the blazar 3C\,279 using multi-wavelength observations from Swift-XRT, Swift-UVOT and Fermi-LAT during a flare in 2018 January. The temporal analysis of $\gamma$-ray light curve indicates a lag of $\sim 1$ d between the 0.1--3 GeV and 3--500 GeV emission. Additionally, the $\gamma$-ray light curve shows asymmetry with slow rise--fast decay in energy band 0.1--3 GeV and fast rise--slow decay in the 3--500 GeV band. We interpret this asymmetry as a result of shift in the Compton spectral peak. This inference is further supported by the correlation studies between the flux and the parameters of the log-parabola fit to the source spectra in the energy range 0.1--500 GeV. We found that the flux correlates well with the peak spectral energy and the log-parabola fit parameters show a hard index with large curvature at high flux states. Interestingly, the hardest index with large curvature was synchronous with a very high energy flare detected by H.E.S.S. Our study of the spectral behavior of the source suggests that $\gamma$-ray emission is most likely to be associated with the Compton up-scattering of IR photons from the dusty environment. Moreover, the fit parameters indicate the increase in bulk Lorentz factor of emission region to be a dominant cause for the flux enhancement.

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Zahir Shah, V. Jithesh, S. Sahayanathan, Ranjeev Misra, Naseer Iqbal. 2019-01-14. Study on Temporal and Spectral behavior of 3C 279 during 2018 January flare. https://doi.org/10.1093/mnras%2Fstz151

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