CANGAROO-III Observation of TeV Gamma Rays from the Unidentified Gamma-Ray Source HESS J1614-518

Abstract

We report the detection, with the CANGAROO-III imaging atmospheric Cherenkov telescope array, of a very high energy gamma-ray signal from the unidentified gamma-ray source HESS J1614-518, which was discovered in the H.E.S.S. Galactic plane survey. Diffuse gamma-ray emission was detected above 760GeV at the 8.9σ level during an effective exposure of 54hr from 2008 May to August. The spectrum can be represented by a power law: (8.2 ± 2.2stat ±2.5sys) × 10-12 × (E/1 TeV)-γcm-2s-1 TeV-1 with a photon index γ of 2.4 ± 0.3stat ±0.2 sys, which is compatible with that of the H.E.S.S. observations. By combining our result with multiwavelength data, we discuss the possible counterparts for HESS J1614-518 and consider radiation mechanisms based on hadronic and leptonic processes for a supernova remnant (SNR), stellar winds from massive stars, and a pulsar wind nebula (PWN). Although a leptonic origin from a PWN driven by an unknown pulsar remains possible, hadronic-origin emission from an unknown SNR is preferred. Show more