Detection of diffuse gamma-ray emission near the young massive cluster NGC 3603

TL;DR

This paper reports the detection of extended gamma-ray emission near the young star cluster NGC 3603, suggesting it as a potential source of cosmic rays with a hadronic origin, similar to the Cygnus cocoon.

Contribution

First detection of extended gamma-ray emission associated with NGC 3603, indicating young star clusters as gamma-ray sources and cosmic ray accelerators.

Findings

Gamma-ray emission shows a hard spectrum with photon index 2.3.

Emission is spatially correlated with ionized gas, indicating a hadronic origin.

Estimated cosmic ray proton energy is around 10^50 erg.

Abstract

We report the Fermi Large Area Telescope's detection of extended gamma-ray emission towards the direction of the young massive star cluster NGC 3603. The emission shows a hard spectrum with a photon index of 2.3 from 1 GeV to 250 GeV. The large size and high luminosity of this structure make it unlikely a pulsar wind nebular. On the other hand the spatial correlation with the ionised gas indicate a hadronic origin. The total cosmic ray (CR) protons energy are estimated to be of the order $10^{50} ~\rm erg$ assuming the gamma-ray are produced in the interaction of CRs with ambient gas . The environment and spectral features show significant similarity with the Cygnus cocoon. It reveals that the young star clusters may be a gamma-ray source population and they can potentially accelerate a significant fraction of the Galactic cosmic rays.