Morphological and spectral study of 4FGL J1115.1-6118 in the region of the young massive stellar cluster NGC 3603

TL;DR

This study analyzes 10 years of Fermi LAT data to identify and characterize a gamma-ray source in the NGC 3603 star-forming region, suggesting it is a gamma-ray emitting star-forming region based on spectral and imaging evidence.

Contribution

It provides the first detailed spectral and morphological analysis of the gamma-ray source in NGC 3603, proposing it as a gamma-ray emitting star-forming region.

Findings

Detected a pointlike gamma-ray source with 9σ significance.

Spectral index of the source is 2.35 ± 0.03.

Deep Chandra imaging rules out extragalactic origin.

Abstract

We report a detailed study of an unidentified gamma-ray source located in the region of the compact stellar cluster NGC 3603. This is a star-forming region (SFR) powered by a massive cluster of OB stars. A dedicated analysis of about 10 years of data from 10 GeV - 1 TeV, provided by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, yields the detection of a pointlike source at a significance of 9$\sigma$. The source photon spectrum can be described by a power-law model with best fit spectral index of $2.35 \pm 0.03$. In addition, the analysis of a deep Chandra image in the 0.5 - 7 keV band reliably rules out an extragalactic origin for the gamma rays. We also conclude that the broadband spectral energy distribution of the point source can be explained well with both leptonic and hadronic models. No firm evidence of association with any other classes of known gamma-ray emitters is found, therefore we speculate that 4FGL J1115.1-6118 is a gamma-ray emitting SFR.