Nonthermal Radiation of the Extreme TeV Blazar 1ES 0229+200 from Electromagnetic Cascades on Infrared Photon Field

TL;DR

This paper introduces a new model for the high-energy spectra of extreme TeV blazars, proposing electromagnetic cascades in infrared photon fields as the key mechanism, successfully fitting the observed spectral energy distribution of 1ES 0229+200.

Contribution

It presents a novel scenario for ETB emission that does not rely on fast-moving 'blob' sources, aligning with their observed slow variability.

Findings

The model fits the observed SED of 1ES 0229+200 well.

Electromagnetic cascades in infrared fields can explain ETB spectra.

The scenario accounts for the lack of rapid variability in ETBs.

Abstract

Extreme TeV blazars (ETBs) are active galactic nuclei with jets presumably pointing towards the observer having their intrinsic spectral energy distributions (SEDs) peaked at an energy in excess of 1 TeV. These sources typically reveal relatively weak and slow variability as well as an extremely high frequency of the low-energy SED peak compared to other classes of blazars. It proved to be exceedingly hard to incorporate all these peculiar properties of ETBs into the framework of a reasonable $\gamma$-ray emission model. ETB physics have recently attracted great attention in the astrophysical community, underlying the importance of the development of self-consistent ETB emission model(s). We propose a new scenario for the formation of X-ray and $\gamma$-ray spectra of ETBs assuming that electromagnetic cascades develop in the infrared photon field surrounding the central blazar engine. This scenario does not invoke compact fast-moving sources of radiation (so-called "blobs"), in agreement with the apparent absence of fast and strong variability of ETBs. For the case of the extreme TeV blazar 1ES 0229+200 we propose a specific emission model in the framework of the considered scenario. We demonstrate that this model allows to obtain a good fit to the measured SED of 1ES 0229+200.