A new nearby pulsar wind nebula overlapping the RX J0852.0−4622 supernova remnant

¹ LUPM, CNRS/Université Montpellier 2, France
e-mail: facero@in2p3.fr
² NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
³ AIM, CEA/CNRS/Université Paris Diderot-Paris 7, France
⁴ APC, CNRS/Université Paris Diderot-Paris 7, France

Received: 27 November 2012
Accepted: 17 December 2012

Abstract

Context. Energetic pulsars can be embedded in a nebula of relativistic leptons that is powered by the dissipation of the rotational energy of the pulsar. The object PSR J0855−4644 is an energetic and fast-spinning pulsar (Ė = 1.1 × 10³⁶ erg s^-1, P = 65 ms) discovered near the southeast rim of the supernova remnant (SNR) RX J0852.0−4622 (aka Vela Jr) by the Parkes multibeam survey. The position of the pulsar is in spatial coincidence with an enhancement in X-rays and TeV γ-rays, which could be due to its putative pulsar wind nebula (PWN).

Aims. The purpose of this study is to search for diffuse non-thermal X-ray emission around PSR J0855−4644 to test for the presence of a PWN and to estimate the distance to the pulsar.

Methods. An X-ray observation was carried out with the XMM-Newton satellite to constrain the properties of the pulsar and its nebula. The absorption column density derived in X-rays from the pulsar and from different regions of the SNR rim was compared with the absorption derived from the atomic (HI) and molecular (¹²CO) gas distribution along the corresponding lines of sight to estimate the distance to the pulsar and to the SNR.

Results. The observation has revealed the X-ray counterpart of the pulsar together with surrounding extended emission, thus confirming the existence of a PWN. The comparison of column densities provided an upper limit to the distance to the pulsar PSR J0855−4644 and the SNR RX J0852.0−4622 (d ≤ 900 pc). Although both objects are at compatible distances, we rule out that the pulsar and the SNR are associated. With this revised distance, PSR J0855 − 4644 is the second most energetic pulsar, after the Vela pulsar, within a radius of 1 kpc and could therefore contribute to the local cosmic-ray e⁻/e⁺ spectrum.