Detection of very-high-energy γ-ray emission from the vicinity of PSRB1706-44 and G343.1-2.3 with H.E.S.S.

Abstract

The γ-ray pulsar PSR B1706-44 and the adjacent supernova remnant (SNR) candidate G343.1-2.3 were observed by H.E.S.S. during a dedicated observation campaign in 2007. As a result of this observation campaign, a new source of very-high-energy (VHE; E > 100 GeV) γ-ray emission, H.E.S.S.J1708-443, was detected with a statistical significance of 7σ, although no significant point-like emission was detected at the position of the energetic pulsar itself. In this paper, the morphological and spectral analyses of the newly-discovered TeV source are presented. The centroid of H.E.S.S.J1708-443 is considerably offset from the pulsar and located near the apparent center of the SNR, at αJ2000 = 17h08 m11s ± 17s and δJ2000 = -44°20′ ± 4′. The source is found to be significantly more extended than the H.E.S.S. point spread function (∼0.1°), with an intrinsic Gaussian width of 0.29° ± 0.04°. Its integral flux between 1 and 10 TeV is ~ 3.8 × 10-12 ph cm-2 s -1, equivalent to 17% of the Crab Nebula flux in the same energy range. The measured energy spectrum is well-fit by a power law with a relatively hard photon index Γ = 2.0 ± 0.1stat ± 0.2 sys. Additional multi-wavelength data, including 330 MHz VLA observations, were used to investigate the VHE γ-ray source's possible associations with the pulsar wind nebula of PSR B1706-44 and/or with the complex radio structure of the partial shell-type SNR G 343.1-2.3. © 2011 ESO.