Proton Synchrotron Radiation from Extended Jets of PKS 0637-752 and 3C 273

TL;DR

This paper proposes proton synchrotron radiation as a viable explanation for X-ray and gamma-ray emissions in quasar jets, challenging previous inverse Compton models and explaining optical data inconsistencies.

Contribution

It introduces a proton synchrotron model for jet emissions in PKS 0637-752 and 3C 273, addressing limitations of prior models and predicting TeV emission from large-scale jets.

Findings

Proton synchrotron can account for X-ray and gamma-ray fluxes in PKS 0637-752.

The model explains optical data points in 3C 273 that electron synchrotron cannot.

Proton synchrotron emission could produce TeV gamma rays from large-scale quasar jets.

Abstract

Recently, the IC/CMB X-ray mechanism has been strongly disfavoured for 3C 273 and PKS 0637-752 since the anomalously hard and steady gamma-ray emission predicted by such models violates the observational results from Fermi-LAT. Here we propose the proton synchrotron origin of the X ray-gamma ray flux from the knots of PKS 0637-752 with a reasonable budget in luminosity, by considering synchrotron radiation from an accelerated proton population. Moreover, for the source 3C 273, some of the optical data points could not be explained by electron synchrotron (Meyer et al. 2015), which we have included in our updated proton synchrotron model. We also show that TeV emission from large scale quasar jets in principle, can arise from proton synchrotron, which we discuss in the context of knot wk8.9 of PKS 0637-752.