Diffuse gamma-ray emission in the vicinity of young star cluster Westerlund 2

Abstract

We report the results of our analysis of the publicly available data obtained by the Large Area Telescope (LAT) on board of the Fermi satellite towards the direction of the young massive star cluster Westerlund 2. We found significant extended gamma-ray emission in the vicinity of Westerlund 2 with a hard power-law energy spectrum extending from 1 GeV to 250 GeV with a photon index of 2.0 +/- 0.1. We argue that amongst several alternatives, the luminous stars in Westerlund 2 are likely sites of acceleration of particles responsible for the diffuse gamma-ray emission of the surrounding interstellar medium. In particular, the young star cluster Westerlund 2 can provide sufficient non-thermal energy to account for the gamma-ray emission. In this scenario, since the gamma-ray production region is significantly larger than the area occupied by the star cluster, we conclude that the gamma-ray production is caused by hadronic interactions of the accelerated protons and nuclei with the ambient gas. In that case, the total energy budget in relativistic particles is estimated of the order of 1e50 erg.

submitted to A&A

References in corpus (9)

• 3FHL: The Third Catalog of Hard Fermi-LAT Sources
• Energy dependent gamma-ray morphology in the Pulsar wind nebula HESSJ1825-137
• Molecular clouds towards RCW 49 and Westerlund 2; Evidence for cluster formation triggered by cloud-cloud collision
• A radiation transfer model for the Milky-Way: I. Radiation fields and application to High Energy Astrophysics
• Detection of extended very-high-energy gamma-ray emission towards the young stellar cluster Westerlund 2
• Unified model for the gamma-ray emission of supernova remnants
• Detection of diffuse gamma-ray emission near the young massive cluster NGC 3603
• Identification of HESS J1303-631 as a Pulsar Wind Nebula through gamma-ray, X-ray and radio observations
• On the Distance and Molecular Environment of Westerlund 2 and HESS J1023-575

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