CTAO Simulations for Potential PeVatron Candidates

TL;DR

This study uses CTAO simulations to evaluate the observatory's ability to detect and analyze PeVatron candidates, focusing on gamma-ray fluxes and proton cut-off energies for specific sources.

Contribution

It demonstrates the potential of CTAO to distinguish PeVatron sources and measure proton cut-off energies using simulations and statistical methods.

Findings

Minimum 100 hours observation needed to detect flux variations.

Detection limit around 600 TeV for proton cut-off energies.

Cassiopeia A, RX J1713.7-3946, HESS J1731-347 excluded as PeVatron sources.

Abstract

This paper reports on the capabilities of the Cherenkov Telescope Array Observatory (CTAO) in detecting high-energy gamma-rays that show significant contributions of hadronic origin. We focus on four sources: RX J1713.7-3946, HESS J1731-347, Cassiopeia A, and HAWC J2227+610, which have been previously identified as PeVatron candidates, sources capable of accelerating hadrons to PeV energies. In this study, we perform simulations using Gammapy for each source to obtain flux estimates for CTAO. In case of HAWC J2227+610, we also determined the maximum cut-off energy in the proton distribution detectable by measuring gamma-rays with CTAO. To distinguish between fluxes with different proton cut-off energies we used the Test Statistic (TS) method. Additionally, we used the PeVatron Test Statistic (PTS) metric to demonstrate whether CTAO could confirm or exclude SNRs as PeVatron candidates. Through this study, we found that a minimum of 100 hours of observation time is required to detect flux variations with different cut-offs, with the detection limit being around 600 TeV. Through the PTS study, SNRs Cassiopeia A, RX J1713.7-3946, and HESS J1731-347 were excluded as PeVatron sources, while HAWC J2227+610 remains inconclusive.