On the origin of TeV gamma-ray emission from HESS J1834-087

Abstract

We present an X-ray study of the field containing the extended TeV source HESS J1834-087 using data obtained with the XMM-Newton telescope. Previously, the coincidence of this source with both the shell-type supernova remnant (SNR) W41 and a giant molecular cloud (GMC) was interpreted as favoring π0-decay γ-rays from interaction of the old SNR with the GMC. Alternatively, the TeV emission has been attributed to inverse Compton scattering from leptons deposited by PSR J1833-0827, a pulsar assumed to have been born in W41 but now located 24′ from the center of the SNR (and the TeV source). Instead, we argue for a third possibility, that the TeV emission is powered by a previously unknown pulsar wind nebula located near the center of W41. The candidate pulsar is XMMU J183435.3-084443, a hard X-ray point source that lacks an optical counterpart to R > 21 and is coincident with diffuse X-ray emission. The X-rays from both the point source and diffuse feature are evidently nonthermal and highly absorbed. A best-fit power-law model yields photon index Γ ∼ 0.2 and Γ ∼ 1.9, for the point source and diffuse emission, respectively, and 2-10 keV flux ≈5 × 10-13 erg cm-2 s-1 for each. At the measured 4 kpc distance of W41, the observed X-ray luminosity implies an energetic pulsar with erg s -1, which is also sufficient to generate the observed γ-ray luminosity of 2.7 × 1034 d 2 4 erg s-1 via inverse Compton scattering. © 2009. The American Astronomical Society. All rights reserved..