Prospects for combined analyses of hadronic emission from [Formula omitted]-ray sources in the Milky Way with CTA and KM3NeT

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2024-02, Vol.84 (2)
• Main Authors: Unbehaun, T, Mohrmann, L, Funk, S, Aiello, S, Albert, A, Garre, S. Alves, Aly, Z
• Format: Article
• Language: English
• Subjects: Public software; Telescope
• ISSN: 1434-6044
• DOI: 10.1140/epjc/s10052-023-12279-z

The Cherenkov Telescope Array and the KM3NeT neutrino telescopes are major upcoming facilities in the fields of [Formula omitted]-ray and neutrino astronomy, respectively. Possible simultaneous production of [Formula omitted] rays and neutrinos in astrophysical accelerators of cosmic-ray nuclei motivates a combination of their data. We assess the potential of a combined analysis of CTA and KM3NeT data to determine the contribution of hadronic emission processes in known Galactic [Formula omitted]-ray emitters, comparing this result to the cases of two separate analyses. In doing so, we demonstrate the capability of Gammapy, an open-source software package for the analysis of [Formula omitted]-ray data, to also process data from neutrino telescopes. For a selection of prototypical [Formula omitted]-ray sources within our Galaxy, we obtain models for primary proton and electron spectra in the hadronic and leptonic emission scenario, respectively, by fitting published [Formula omitted]-ray spectra. Using these models and instrument response functions for both detectors, we employ the Gammapy package to generate pseudo data sets, where we assume 200 h of CTA observations and 10 years of KM3NeT detector operation. We then apply a three-dimensional binned likelihood analysis to these data sets, separately for each instrument and jointly for both. We find that the largest benefit of the combined analysis lies in the possibility of a consistent modelling of the [Formula omitted]-ray and neutrino emission. Assuming a purely leptonic scenario as input, we obtain, for the most favourable source, an average expected 68% credible interval that constrains the contribution of hadronic processes to the observed [Formula omitted]-ray emission to below 15%.