Deciphering the multi-wavelength flares of the most distant very high-energy (>100 GeV) γ-ray emitting blazar

Abstract

This study analyzes the multi-wavelength flaring activity of the distant flat spectrum radio quasar (FSRQ) OP 313 (z=0.997) during November 2023 to March 2024, using data from Fermi-Large Area Telescope, Swift X-ray Telescope, and Ultraviolet and Optical Telescope. The analysis highlights two significant very high energy (VHE) detection epochs and GeV gamma-ray flaring episodes, providing insight into jet emission processes and radiative mechanisms. We study the evolution of broadband spectral energy distribution (SED) and identify, for the first time, that the source displays three different characteristics in its synchrotron peaks within a short span of four months, which is rather uncommon in FSRQs. Modeling of the multi-wavelength SED with a one-zone leptonic radiative processes attributes the emissions to synchrotron radiation, Synchrotron Self-Compton (SSC), and External Compton (EC) mechanisms, with torus photons as the primary source for EC processes. The results suggest that the gamma-ray emitting region lies outside the broad-line region but within the dusty torus. Furthermore, we find that the radiated power is significantly smaller than the total jet power, suggesting that most of the bulk energy remains within the jet even after passing through the blazar emission zone.