Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54

TL;DR

This study presents detailed Chandra X-ray observations of the pulsar wind nebula around PSR B0355+54, revealing its morphology, spectral properties, and potential particle re-acceleration mechanisms, advancing understanding of pulsar wind nebulae structures.

Contribution

First detailed X-ray analysis of PSR B0355+54's PWN, including morphology, spectral features, and implications for particle acceleration and magnetic field properties.

Findings

Compact nebula suggests a small angle between spin axis and line-of-sight.

Extended tail emission observed up to 7 arcminutes (2 pc).

Tail spectrum shows minimal cooling, indicating possible re-acceleration or low magnetic field.

Abstract

We report on Chandra X-ray Observatory (CXO) observations of the pulsar wind nebula (PWN) associated with PSR B0355+54 (eight observations with a 395 ks total exposure, performed over an 8 month period). We investigated the spatial and spectral properties of the emission coincident with the pulsar, compact nebula (CN), and extended tail. We find that the CN morphology can be interpreted in a way that suggests a small angle between the pulsar spin axis and our line-of-sight, as inferred from the radio data. On larger scales, emission from the 7' (2 pc) tail is clearly seen. We also found hints of two faint extensions nearly orthogonal to the direction of the pulsar's proper motion. The spectrum extracted at the pulsar position can be described with an absorbed power-law + blackbody model. The nonthermal component can be attributed to magnetospheric emission, while the thermal component can be attributed to emission from either a hot spot (e.g., a polar cap) or the entire neutron star surface. Surprisingly, the spectrum of the tail shows only a slight hint of cooling with increasing distance from the pulsar. This implies either a low magnetic field with fast flow speed, or particle re-acceleration within the tail. We estimate physical properties of the PWN and compare the morphologies of the CN and the extended tail with those of other bow shock PWNe observed with long CXO exposures.