The population of Galactic young massive star clusters in the TeV range

TL;DR

This paper models the population of young massive star clusters in our galaxy to understand their gamma-ray emissions and their role in cosmic-ray acceleration, using Monte Carlo simulations constrained by current observations.

Contribution

It introduces a Monte Carlo simulation approach to study YMSC gamma-ray emissions and compares results with existing surveys to explore particle acceleration mechanisms.

Findings

Simulated YMSC populations match observed TeV sources.

Constraints on particle acceleration efficiency in YMSCs.

Insights into the fraction of wind luminosity converted into magnetic turbulence.

Abstract

Young massive star clusters (YMSCs) can produce gamma rays in the very-high-energy (VHE, E>100 GeV) range and have been proposed as sources that can accelerate cosmic rays up to PeV energies. Observations with current instruments have lead to the detection of only a few YMSCs but future instruments should significantly increase this number. However, the details of the production of the VHE emission are not well understood: What is the spectrum of accelerated particles? What is the efficiency of cosmic-ray production? What fraction of the wind luminosity is converted into the turbulent magnetic field? To address these questions, we simulate the population of YMSCs in the gamma-ray domain, by means of Monte Carlo methods, and apply the constraints based on the subsample of YMSCs currently detected at TeV energies. We confront our simulated populations with the catalogue of the H.E.S.S. Galactic Plane Survey and the First LHAASO Catalogue of Gamma-Ray Sources, allowing us to investigate crucial aspects of particle acceleration at YMSCs.