Massive Star Clusters as sources of high-energy gamma radiation

TL;DR

This study models how massive star clusters, especially young and compact ones near Earth, accelerate protons that produce high-energy gamma rays, contributing to the galaxy's ultra-high-energy emission.

Contribution

It introduces a detailed model of proton acceleration in different types of massive star clusters and their role in gamma-ray production, focusing on nearby clusters within 3 kpc.

Findings

Young, compact clusters significantly contribute to multi-TeV to PeV gamma-ray emission.

Nearby clusters within 3 kpc are the dominant sources of high-energy gamma rays.

Proton acceleration in supernova remnant shock waves within clusters explains observed gamma-ray fluxes.

Abstract

This paper investigates the contribution of massive star clusters (MSC) as sources of high-energy gamma rays and their impact on the ultra-high-energy (UHE) emission observed throughout the Galaxy. By modeling proton injection, the study explores how the acceleration of protons in massive star clusters contributes to the gamma radiation detectable from Earth. The analysis focuses on two primary types of clusters: widespread, dispersed clusters and younger, compact massive clusters, both of which host shock waves generated by supernova remnants (SNR). Clusters located near the solar system, within a 3-kiloparsec radius,are identified. Analytical methods are used to calculate energy spectra and gamma-ray production rates. The findings suggest that young and compact MSC contribute to multi-TeV to PeV gamma-ray emission, with the dominant contribution arising from nearby populations.