Very high energy emission mechanism in the extreme blazar PGC 2402248

TL;DR

This paper models the very high-energy gamma-ray emission from the extreme blazar PGC 2402248 using the photohadronic model, showing it fits the observed data well and suggesting a low emission state with a Lorentz factor below 34.

Contribution

It extends the photohadronic model to explain VHE gamma-ray flaring in PGC 2402248 and compares its effectiveness with other models.

Findings

Photohadronic model fits the VHE data well.

The spectrum indicates a low emission state.

Bulk Lorentz factor estimated to be less than 34.

Abstract

Extreme high-frequency peaked BL Lacs (EHBLs) are characterized by a synchrotron peak frequency exceeding $10^{17}$ Hz and a second peak that can be in the energy range of few GeVs to several TeVs. The MAGIC telescopes detected multi-TeV gamma-rays on April 19, 2018 for the first time from the EHBL PGC 2402248 which was simultaneously observed in multiwavelength by several other instruments. The broad band spectral energy distribution of the source is conventionally modelled using the leptonic and the hadronic models. Due to the success of the photohadronic model in interpreting the enigmatic very high-energy (VHE) flaring events from many high-energy blazars, we extend this model to explain the VHE events from PGC 2402248 observed by MAGIC telescopes and compare our results with other models. We conclude that the photohadronic fits are comparable and even fare better than most other models. Furthermore, we show that the spectrum is not hard and is in a low emission state. The estimated bulk Lorentz factor for this flaring event is found to be $\lesssim 34$.