Abstract:
The blazar 3C 279 exhibited twin
γ
-ray
fl
ares of similar intensity in 2013 December and 2014 April. In this work,
we present a detailed multi-wavelength analysis of the 2013 December
fl
aring event. Multi-frequency observations
reveal the uncorrelated variability patterns with X-ray and optical
–
UV
fl
uxes peaking after the
γ
-ray maximum.
The broadband spectral energy distribution
(
SED
)
at the peak of the
γ
-ray activity shows a rising
γ
-ray spectrum
but a declining optical
–
UV
fl
ux. This observation along with the detection of uncorrelated variability behavior
rules out the one-zone leptonic emission scenario. We, therefore, adopt two independent methodologies to explain
the SED: a time-dependent lepto-hadronic modeling and a two-zone leptonic radiative modeling approach. In the
lepto-hadronic modeling, a distribution of electrons and protons subjected to a randomly orientated magnetic
fi
eld
produces synchrotron radiation. Electron synchrotron is used to explain the IR to UV emission while proton
synchrotron emission is used to explain the high-energy
γ
-ray emission. A combination of both electron
synchrotron self-Compton emission and proton synchrotron emission is used to explain the X-ray spectral break
seen during the later stage of the
fl
are. In the two-zone modeling, we assume a large emission region emitting
primarily in IR to X-rays and
γ
-rays to come primarily from a fast-moving compact emission region. We conclude
by noting that within a span of four months, 3C 279 has shown the dominance of a variety of radiative processes
over each other and this re
fl
ects the complexity involved in understanding the physical properties of blazar jets in
general.
