XMM-NEWTON AND CHANDRA OBSERVATIONS OF THE FILLED-CENTER SUPERNOVA REMNANT G63.7+1.1

Abstract

ABSTRACT Pulsar wind nebulae (PWNe) provide unique opportunities to study relativistic pulsar winds and their interaction with the surrounding medium. G63.7+1.1 is an intriguing supernova remnant studied so far only at radio wavelengths and classified as a PWN candidate based on its nonthermal radio emission. We present the first X-ray study of G63.7+1.1, obtained with XMM-Newton and the Chandra X-ray Observatory, with the goal of detecting and studying the candidate PWN in X-rays and searching for the neutron star candidate. The peak of the X-ray emission lies approximately 1.′2 from the peak of the 21 cm continuum emission and is offset from the center of the X-ray nebula. The diffuse X-ray emission is irregularly shaped (4.′2 × 3.′2), unlike the nearly symmetric 8′-diameter radio nebula. Its X-ray spectrum is fit with a power-law model, yielding a photon index of , a column density of (1.6 ± 0.5) × 1022 cm−2, and an X-ray luminosity of ∼2 × 1033 erg s−1 (0.5–10.0 keV) at a kinematic distance of 6 kpc. Several point-like sources were detected within the limit of the X-ray nebula. We present a study of their spectra, identifying 3XMM J194753.4+274357 (CXO J194753.3+274351) as a candidate for the location of the neutron star powering the nebula. Located in a dense environment, we estimate that G63.7+1.1 is old enough (≥8 kyr) for the reverse shock to have interacted with the PWN. This, together with the large size estimated from radio studies (∼14 pc) and the offset between the radio and X-ray peaks, suggests an evolved nebula, with the radio nebula being a “relic” PWN.