Swift/XRT view on S5 0716+714 during a flare

TL;DR

This study reports on Swift/XRT observations of the blazar S5 0716+714 during a major flare, revealing spectral changes, component dominance shifts, and intranight variability in X-ray emissions.

Contribution

First detailed X-ray spectral analysis during a flare of S5 0716+714, showing synchrotron dominance and spectral evolution with flux.

Findings

Break energy shifts to higher energies with increasing flux

Spectrum softens as flux increases

Significant intranight X-ray variability observed

Abstract

The blazar S5 0716+714 has been monitored in its flaring state between 2015 January 19 and February 22 with Swift/XRT. During this period an exceptional flux level was observed in the X-ray range as well as in the other wavelengths, e.g. optical, near infrared and very high energy $\gamma$ rays. Here, we report X-ray observations of S5 0716+714 carried out during the outburst. The observed X-ray spectra, well described with broken power-law model, disentangle both synchrotron and inverse Compton components. The break energy shifts towards higher energies with increasing flux, revealing the dominance of synchrotron radiation in the X-ray spectrum observed. We also report spectrum softening with increasing flux. During the recent flare, significant temporal intranight variability is observed in the X-ray range.