Diffuse gamma-ray emissions around the stellar cluster Berkeley 59

TL;DR

This study analyzes extended gamma-ray emission around Berkeley 59 using Fermi-LAT data, revealing cosmic ray interactions with surrounding gas as the emission's origin.

Contribution

It provides the first detailed analysis of GeV emission around Berkeley 59, modeling the emission as a radial disk and exploring cosmic ray acceleration and diffusion.

Findings

Extended gamma-ray emission modeled as a 1.02° radius disk

Gamma-ray spectrum with photon index 2.88

Gas mass around Berkeley 59 is approximately 289 solar masses

Abstract

We report a detailed analysis on the young stellar cluster Berkeley 59 using Fermi-LAT. Using up-to-date source catalog and background models, we found significant extended GeV emission around Berkeley 59, which can be modeled by a radial disk of 1.02 degree radius with a significance of the extension of 10.6 sigma. We investigated the molecular, neutral and ionized gas content and the hadronic origin. The gamma-ray spectrum of Berkeley 59 has a photon index of 2.88. The derived gas mass from H2 and HII around Berkeley 59 is about 289 solar mass. We derived the relationship between cosmic ray acceleration efficiency and diffusion coefficient. Our results suggest that the extended gamma-ray emission originates from cosmic rays accelerated by cluster winds interacting with surrounding gas.