Chandra Confirmation of a Pulsar Wind Nebula in DA 495

TL;DR

This study confirms the presence of a pulsar wind nebula in DA 495 using Chandra X-ray observations, revealing properties consistent with a young, energetic neutron star and its surrounding nebula, and suggests a highly magnetized wind environment.

Contribution

First detailed X-ray analysis of DA 495 confirming its pulsar wind nebula and characterizing its emission components and morphology.

Findings

Detected a neutron star with a blackbody temperature of 1 MK.

Identified a nonthermal nebula with a photon index of 1.6.

Estimated the neutron star's spin-down luminosity at ~10^{35} ergs/s.

Abstract

As part of a multiwavelength study of the unusual radio supernova remnant DA 495, we present observations made with the Chandra X-ray Observatory. Imaging and spectroscopic analysis confirms the previously detected X-ray source at the heart of the annular radio nebula, establishing the radiative properties of two key emission components: a soft unresolved source with a blackbody temperature of 1 MK consistent with a neutron star, surrounded by a nonthermal nebula 40'' in diameter exhibiting a power-law spectrum with photon index Gamma = 1.6+/-0.3, typical of a pulsar wind nebula. The implied spin-down luminosity of the neutron star, assuming a conversion efficiency to nebular flux appropriate to Vela-like pulsars, is ~10^{35} ergs/s, again typical of objects a few tens of kyr old. Morphologically, the nebular flux is slightly enhanced along a direction, in projection on the sky, independently demonstrated to be of significance in radio polarization observations; we argue that this represents the orientation of the pulsar spin axis. At smaller scales, a narrow X-ray feature is seen extending out 5'' from the point source, a distance consistent with the sizes of resolved wind termination shocks around many Vela-like pulsars. Finally, we argue based on synchrotron lifetimes in the estimated nebular magnetic field that DA 495 represents a rare pulsar wind nebula in which electromagnetic flux makes up a significant part, together with particle flux, of the neutron star's wind, and that this high magnetization factor may account for the nebula's low luminosity.