Signatures of relativistic protons in CTA blazar spectra

TL;DR

This paper explores CTA's potential to detect spectral signatures indicating relativistic protons in blazar spectra, which could shed light on the origin of extragalactic cosmic rays, by comparing hadronic and leptonic emission scenarios.

Contribution

It assesses CTA's capability to identify proton signatures in blazar spectra and evaluates how array configurations affect detection prospects.

Findings

CTA can potentially detect hadronic spectral features in bright BL Lac objects.

Array configuration impacts the detectability of proton signatures.

Comparison shows differences between hadronic and leptonic emission features.

Abstract

The Cherenkov Telescope Array (CTA) will provide very-high-energy (VHE; >~30 GeV) gamma-ray spectra of unprecedented resolution over a large energy range. It is likely that, at least for bright sources, spectral features will be revealed that cannot be distinguished with the current generation of Cherenkov telescopes. We are investigating the capability of the CTA to detect spectral signatures in TeV bright BL Lac objects that could reveal the emission from a population of relativistic protons in those sources. Such a detection would be crucial for the long-standing question of the origin of extragalactic cosmic rays. As a first step, the expected VHE emission from hadronic scenarios is compared to the spectral features that might arise in the more commonly assumed leptonic scenarios for a given source. We also evaluate the impact of different array configurations on the detectability of such features.