Investigation of CTA 1 with Suzaku Observation

TL;DR

This study presents a detailed Suzaku X-ray observation of the CTA 1 supernova remnant, revealing a bow-shock feature of the pulsar wind nebula, analyzing its spectrum, and discussing the non-detection of pulsations and future observational prospects.

Contribution

First detailed Suzaku observation of CTA 1 revealing a bow-shock PWN feature and spectral analysis without pulsation detection.

Findings

Extended bow-shock feature with a photon index of ~1.8

No significant pulsation detected from the central pulsar

Spectra from XIS and HXD can be connected without spectral break

Abstract

We report on an 105 ks Suzaku observation of the supernova remnant CTA 1 (G119.5+10.2). The Suzaku soft X-ray observation was carried out with both timing mode and imaging mode. A ~ 10' extended feature, which is interpreted as a bow-shock component of the pulsar wind nebula (PWN), is revealed in this deep observation for the first time. The nebular spectrum can be modelled by a power-law with a photon index of ~ 1.8 which suggests a slow synchrotron cooling scenario. The photon index is approximately constant across this extended feature. We compare and discuss our observations of this complex nebula with previous X-ray investigations. We do not obtain any significant pulsation from the central pulsar in the soft (0.2-12 keV) and hard (10-60 keV) X-ray data. The non-detection is mainly due to the loss of the precise imaging ability to accurately determine the source contribution. The spectra of XIS and HXD can be directly connected without a significant spectral break according to our analysis. Future observations of NuSTAR and Astro-H would be able to resolve the contamination and provide an accurate hard X-ray measurement of CTA 1.