The mid-2016 flaring activity of the flat spectrum radio quasar PKS 2023-07

TL;DR

This paper reports on a significant gamma-ray flare from the FSRQ PKS 2023-07 in April 2016, combining multi-wavelength data to constrain the emission region's location and physical processes, with implications for gamma-ray opacity and jet models.

Contribution

The study provides detailed multi-wavelength observations of a major flare, constraining the gamma-ray emission site beyond the Broad Line Region in PKS 2023-07.

Findings

Detection of a 44 GeV photon during peak emission

Emission region located beyond the Broad Line Region

Constraints on gamma-ray opacity during flaring activity

Abstract

Flat spectrum radio quasars (FSRQs) can suffer strong absorption above E = 25/(1+z) GeV, due to gamma-gamma interaction if the emitting region is at sub-parsec scale from the super-massive black hole (SMBH). Gamma-ray flares from these astrophysical sources can investigate the location of the high-energy emission region and the physics of the radiating processes. We present a remarkable gamma-ray flaring activity from FSRQ PKS 2023-07 during April 2016, as detected by both AGILE and Fermi satellites. An intensive multi-wavelength campaign, triggered by Swift, covered the entire duration of the flaring activity, including the peak gamma-ray activity. We report the results of multiwavelength observations of the blazar. We found that, during the peak emission, the most energetic photon had an energy of 44 GeV, putting strong constraints on the opacity of the gamma-ray dissipation region. The overall Spectral Energy Distribution (SED) is interpreted in terms of leptonic models for blazar jet, with the emission site located beyond the Broad Line Region (BLR).