Eur. Phys. J. C (2024) 84: 112
https://doi.org/10.1140/epjc/s10052-023-12279-z

Regular Article - Experimental Physics

Prospects for combined analyses of hadronic emission from $\gamma$-ray sources in the Milky Way with CTA and KM3NeT

¹ Erlangen Centre for Astroparticle Physics, University of Erlangen-Nuremberg, Nikolaus-Fiebiger-Str. 2, 91058, Erlangen, Germany
² Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg, Germany
³ INFN, Sezione di Catania, Via Santa Sofia 64, 95123, Catania, Italy
⁴ CNRS, IPHC UMR 7178, Université de Strasbourg, 67000, Strasbourg, France
⁵ IFIC-Instituto de Física Corpuscular (CSIC-Universitat de València), c/Catedrático José Beltrán 2, 46980, Paterna, Valencia, Spain
⁶ CNRS/IN2P3, CPPM, Aix Marseille Univ, Marseille, France
⁷ INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia ed. G, 80126, Naples, Italy
⁸ Università di Napoli “Federico II”, Dip. Scienze Fisiche “E. Pancini”, Complesso Universitario di Monte S. Angelo, Via Cintia ed. G, 80126, Naples, Italy
⁹ INFN, Sezione di Roma, Piazzale Aldo Moro 2, 00185, Rome, Italy
¹⁰ Laboratori d’Aplicacions Bioacústiques, Centre Tecnològic de Vilanova i la Geltrú, Universitat Politècnica de Catalunya, Avda. Rambla Exposició s/n, 08800, Vilanova i la Geltrú, Spain
¹¹ Institute of Nuclear and Particle Physics, NCSR Demokritos, Ag. Paraskevi Attikis, 15310, Athens, Greece
¹² INFN, Sezione di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
¹³ Department of Computer Architecture and Technology/CITIC, University of Granada, 18071, Granada, Spain
¹⁴ Subatech, IMT Atlantique, IN2P3-CNRS, Université de Nantes, BP 20722, 4 rue Alfred Kastler-La Chantrerie, 44307, Nantes, France
¹⁵ Instituto de Investigación para la Gestión Integrada de las Zonas Costeras, Universitat Politècnica de València, C/ Paranimf 1, 46730, Gandia, Spain
¹⁶ Faculty of Sciences, University Mohammed V in Rabat, B.P. 1014, 4 av. Ibn Battouta, R.P. 10000, Rabat, Morocco
¹⁷ CNRS, Astroparticule et Cosmologie, Université Paris Cité, 75013, Paris, France
¹⁸ LPC CAEN, Normandie Univ, ENSICAEN, UNICAEN, CNRS/IN2P3, 6 Boulevard Maréchal Juin, 14050, Caen, France
¹⁹ Nikhef, National Institute for Subatomic Physics, PO Box 41882, 1009 DB, Amsterdam, The Netherlands
²⁰ INFN, Sezione di Bologna, v.le C. Berti-Pichat 6/2, 40127, Bologna, Italy
²¹ Dipartimento di Fisica e Astronomia, Università di Bologna, v.le C. Berti-Pichat 6/2, 40127, Bologna, Italy
²² Dipartimento di Matematica e Fisica, Università degli Studi della Campania “Luigi Vanvitelli”, Viale Lincoln 5, 81100, Caserta, Italy
²³ E. A. Milne Centre for Astrophysics, University of Hull, HU6 7RX, Hull, UK
²⁴ INFN, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123, Catania, Italy
²⁵ Centre for Space Research, North-West University, Private Bag X6001, 2520, Potchefstroom, South Africa
²⁶ Instituto Español de Oceanografía, Unidad Mixta IEO-UPV, C/ Paranimf 1, 46730, Gandia, Spain
²⁷ Faculty of Sciences, University Mohammed I, B.P. 717, BV Mohammed VI, R.P. 60000, Oujda, Morocco
²⁸ Dipartimento di Fisica, Università di Salerno e INFN Gruppo Collegato di Salerno, Via Giovanni Paolo II 132, 84084, Fisciano, Italy
²⁹ ISS, Atomistilor 409, 077125, Măgurele, Romania
³⁰ Institute of Physics/IHEF, University of Amsterdam, PO Box 94216, 1090 GE, Amsterdam, The Netherlands
³¹ TNO, Technical Sciences, PO Box 155, 2600 AD, Delft, The Netherlands
³² Dipartimento di Fisica, Università La Sapienza, Piazzale Aldo Moro 2, 00185, Rome, Italy
³³ Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione ”Guglielmo Marconi”, Università di Bologna, Via dell’Università 50, 47521, Cesena, Italy
³⁴ Physics Department, Faculty of Science Semlalia, Cadi Ayyad University, P.O.B. 2390, Av. My Abdellah, 40000, Marrakech, Morocco
³⁵ School of Physics, University of the Witwatersrand, Private Bag 3, 2050, Johannesburg, Wits, South Africa
³⁶ Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, Via Santa Sofia 64, 95123, Catania, Italy
³⁷ INFN, Sezione di Bari, Via Orabona 4, 70125, Bari, Italy
³⁸ International Centre for Radio Astronomy Research, Curtin University, 6102, Bentley, WA, Australia
³⁹ University Würzburg, Emil-Fischer-Straße 31, 97074, Würzburg, Germany
⁴⁰ Comenius University in Bratislava, Department of Nuclear Physics and Biophysics, Mlynska dolina F1, 842 48, Bratislava, Slovak Republic
⁴¹ School of Computing, Engineering and Mathematics, Western Sydney University, Locked Bag 1797, 2751, Penrith, NSW, Australia
⁴² IN2P3, LPC, Campus des Cézeaux 24, BP 80026, Avenue des Landais, 63171, Aubière Cedex, France
⁴³ Università di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
⁴⁴ Dpto. de Física Teórica y del Cosmos & C.A.F.P.E., University of Granada, 18071, Granada, Spain
⁴⁵ NIOZ (Royal Netherlands Institute for Sea Research), PO Box 59, Den Burg, 1790 AB, Texel, The Netherlands
⁴⁶ Leiden Institute of Physics, Leiden University, PO Box 9504, 2300 RA, Leiden, The Netherlands
⁴⁷ National Centre for Nuclear Research, 02-093, Warsaw, Poland
⁴⁸ Department of Physics, Tbilisi State University, 3, Chavchavadze Ave., 0179, Tbilisi, Georgia
⁴⁹ Institute of Physics, The University of Georgia, Kostava str. 77, 0171, Tbilisi, Georgia
⁵⁰ Institut Universitaire de France, 1 Rue Descartes, 75005, Paris, France
⁵¹ IN2P3, 3, Rue Michel-Ange, 75794, Paris 16, France
⁵² LPC, Campus des Cézeaux 24, BP 80026, Avenue des Landais, 63171, Aubière Cedex, France
⁵³ Department Physics, University of Johannesburg, PO Box 524, 2006, Auckland Park, South Africa
⁵⁴ Laboratorio CIRCE, Dip. Di Matematica e Fisica, Università degli Studi della Campania “Luigi Vanvitelli”, CAPACITY, Viale Carlo III di Borbone 153, 81020, San Nicola La Strada, Italy
⁵⁵ Czech Technical University in Prague, Institute of Experimental and Applied Physics, Husova 240/5, 110 00, Prague, Czech Republic
⁵⁶ Laboratoire Univers et Particules de Montpellier, Place Eugène Bataillon-CC 72, 34095, Montpellier Cédex 05, France
⁵⁷ Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Remeis Sternwarte, Sternwartstraße 7, 96049, Bamberg, Germany
⁵⁸ Université de Haute Alsace, Rue des Frères Lumière, 68093, Mulhouse Cedex, France
⁵⁹ Institut für Kernphysik, University of Münster, Wilhelm-Klemm-Str. 9, 48149, Münster, Germany
⁶⁰

^a km3net-pc@km3net.de
^c tim.unbehaun@fau.de
^d lars.mohrmann@mpi-hd.mpg.de

Received: 8 August 2023
Accepted: 21 November 2023
Published online: 2 February 2024

Abstract

The Cherenkov Telescope Array and the KM3NeT neutrino telescopes are major upcoming facilities in the fields of $\gamma$-ray and neutrino astronomy, respectively. Possible simultaneous production of $\gamma$ 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 $\gamma$-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 $\gamma$-ray data, to also process data from neutrino telescopes. For a selection of prototypical $\gamma$-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 $\gamma$-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 $\gamma$-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 $\gamma$-ray emission to below 15%.