Discovery of the VHE gamma-ray source HESS J1832-093 in the vicinity of SNR G22.7-0.2

Abstract

The region around the supernova remnant (SNR) W41 contains several TeV sources and has prompted the HESS Collaboration to perform deep observations of this field of view. This resulted in the discovery of the new very high energy (VHE) source HESS J1832−093, at the position RA=18h32m50s±3sstat±2ssyst,Dec=−9∘22′36′′±32′′stat±20′′syst(J2000), spatially coincident with a part of the radio shell of the neighbouring remnant G22.7−0.2. The photon spectrum is well described by a power law of index Γ = 2.6 ± 0.3stat ± 0.1syst and a normalization at 1 TeV of Φ0=(4.8±0.8stat±1.0syst)×10−13cm−2s−1TeV−1. The location of the gamma-ray emission on the edge of the SNR rim first suggested a signature of escaping cosmic rays illuminating a nearby molecular cloud. Then a dedicated XMM–Newton observation led to the discovery of a new X-ray point source spatially coincident with the TeV excess. Two other scenarios were hence proposed to identify the nature of HESS J1832−093. Gamma-rays from inverse Compton radiation in the framework of a pulsar wind nebula scenario or the possibility of gamma-ray production within a binary system are therefore also considered. Deeper multiwavelength observations will help to shed new light on this intriguing VHE source.