Letter to the Editor

Discovery of an X-ray nebula around PSR J1718-3825 and implications for the nature of the γ-ray source HESS J1718–385

¹ School of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, UK e-mail: j.a.hinton@leeds.ac.uk
² Kavli Institute for Particle Astrophysics and Cosmology, SLAC, 2575 Sand Hill Road, Menlo-Park, CA-94025, USA
³ Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
⁴ Laboratoire de Physique Théorique et Astroparticules, CNRS/IN2P3, Université Montpellier II, CC 70, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
⁵ Unit for Space Physics, North-West University, Potchefstroom 2520, South Africa
⁶ CFA - Harvard, 60 Garden Street, 02138 Cambridge MA, USA
⁷ Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany

Received: 1 October 2007
Accepted: 26 October 2007

Abstract

Combined X-ray synchrotron and inverse-Compton γ-ray observations of pulsar wind nebulae (PWN) may help to elucidate the processes of acceleration and energy loss in these systems. In particular, such observations provide constraints on the particle injection history and the magnetic field strength in these objects. The newly discovered TeV γ-ray source HESS J1718-385 has been proposed as the likely PWN of the high spin-down luminosity pulsar PSR J1718-3825. The absence of previous, sensitive X-ray measurements of this pulsar, and the unusual energy spectrum of the TeV source, motivated observations of this region with XMM-Newton. The data obtained reveal a hard-spectrum X-ray source at the position of PSR 1718-3825 and evidence of diffuse emission in the vicinity of the pulsar. We derive limits on the keV emission from the centroid of HESS J1718-385 and discuss the implications of these findings for the PWN nature of this object.