Investigating the capability of the Cherenkov Telescope Array Observatory to detect gamma-ray emission from simulated stationary neutrino sources identified by KM3NeT

Abstract

The simultaneous observation of gamma rays and neutrinos from the same astrophysical source offers a unique opportunity to probe particle acceleration and interaction mechanisms in ultra-high-energy environments. The Cherenkov Telescope Array Observatory (CTAO) is a next-generation ground-based gamma-ray facility, sensitive to energies from 20~GeV to 300~TeV. In this work, we present for the first time a performance study of CTAO based on joint simulations of steady-state sources emitting both neutrinos and gamma rays, under the assumption that neutrino events are detected by the KM3NeT telescope in the Northern Hemisphere. To identify potentially observable sources, we apply a neutrino-based selection filter according to KM3NeT's discovery potential. We then simulate gamma-ray detectability with CTAO, taking into account visibility, sensitivity, and extragalactic background light absorption. The analysis is specifically focused on exploring the detectability of sources at low neutrino luminosities, limited to values below $10^{52}\,\mathrm{erg\,yr^{-1}}$, in order to assess the performance of CTAO and KM3NeT in identifying faint extragalactic emitters. Particular attention is given to the strategic role of KM3NeT's geographic location, which provides access to Southern-sky sources, and to the impact of the planned CTA+ upgrade, which will enhance CTAO-South with Large-Sized Telescopes (LSTs). Our results highlight the importance of coordinated multi-messenger strategies between KM3NeT and CTAO to maximize the discovery potential of astrophysical neutrino sources.