Gamma-rays and neutrinos from dense environment of massive binary systems in open clusters

TL;DR

This paper models high-energy gamma-ray and neutrino production in dense environments of massive binary systems within open clusters, focusing on particle acceleration, interactions, and detectability with current telescopes.

Contribution

It introduces a detailed calculation of proton and neutron injection rates and resulting gamma-ray and neutrino fluxes from binary systems in open clusters, considering stellar wind interactions.

Findings

Gamma-ray emission from binary systems can be detectable by Cherenkov telescopes.

Neutrino fluxes are within reach of IceCube sensitivity.

Model predictions are consistent with current neutrino upper limits.

Abstract

TeV gamma-ray emission has been recently observed from direction of a few open clusters containing massive stars. We consider the high energy processes occurring within massive binary systems and in their dense environment by assuming that nuclei, from the stellar winds of massive stars, are accelerated at the collision region of the stellar winds. We calculate the rates of injection of protons and neutrons from fragmentation of these nuclei in collisions with stellar radiation and matter of the winds from the massive companions in binary system. Protons and neutrons can interact with the matter, within the stellar wind cavity and within the open cluster, producing pions which decay into $\gamma$-rays and neutrinos. We discuss the detectability of such $\gamma$-ray emission by the present and future Cherenkov telescopes for the case of two binary systems Eta Carinae, within the Carina Nebula, and WR 20a, within the Westerlund 2 open cluster. We also calculate the neutrino fluxes produced by protons around the binary systems and within the open clusters. This neutrino emission is confronted with ANTARES upper limits on the neutrino fluxes from discrete sources and with the sensitivity of IceCube.