Observation of an extended VHE gamma-ray emission from MSH 15-52 with CANGAROO-III

TL;DR

This paper reports the detection of extended very high energy gamma-ray emission from the supernova remnant MSH 15-52 using CANGAROO-III, confirming previous observations and analyzing the emission's origin.

Contribution

First detection of extended VHE gamma-ray emission from MSH 15-52 with CANGAROO-III, consistent with prior H.E.S.S. results, and analysis of its spectral and morphological properties.

Findings

Gamma rays detected above 810 GeV at 7 sigma significance.

Differential flux at 2.35 TeV measured as (7.9±1.5±1.7)×10^{-13} cm^{-2}s^{-1}TeV^{-1}.

Emission shows extended morphology compared to point source.

Abstract

We have observed the supernova remnant MSH 15-52 (G320.4-1.2), which contains the gamma-ray pulsar PSR B1509-58, using the CANGAROO-III imaging atmospheric Cherenkov telescope array from April to June in 2006. We detected gamma rays above 810 GeV at the 7 sigma level during a total effective exposure of 48.4 hours. We obtained a differential gamma-ray flux at 2.35 TeV of (7.9+/-1.5_{stat}+/-1.7_{sys}) \times 10^{-13} cm^{-2}s^{-1}TeV^{-1} with a photon index of 2.21+/-0.39_{stat}+/-0.40_{sys}, which is compatible with that of the H.E.S.S. observation in 2004. The morphology shows extended emission compared to our Point Spread Function. We consider the plausible origin of the high energy emission based on a multi-wavelength spectral analysis and energetics arguments.