Chandra observation of the Galactic supernova remnant CTB 109 (G109.1-1.0)

TL;DR

This study uses Chandra X-ray observations to analyze the supernova remnant CTB 109, revealing ejecta signatures, shock interactions with the interstellar medium, and estimating its age at approximately 14,000 years.

Contribution

First detection of ejecta in CTB 109, providing detailed spectral analysis and insights into shock-medium interactions and remnant evolution.

Findings

Detection of enhanced Si and Fe abundances around the Lobe

Identification of ejecta in CTB 109 for the first time

Estimated SNR age of approximately 14,000 years

Abstract

Context: We study the X-ray emission of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0), which is well-known for its enigmatic half-shell morphology both in radio and in X-rays and is associated with the anomalous X-ray pulsar (AXP) 1E2259+586. Aims: We want to understand the origin of the X-ray bright feature inside the SNR called the Lobe and the details of the interaction of the SNR shock wave with the ambient interstellar medium (ISM). Methods: The Lobe and the northeastern part of the SNR were observed with Chandra ACIS-I. We analysed the spectrum of the X-ray emission by dividing the entire observed emission into small regions. The X-ray emission is best reproduced with one-component or two-component non-equilibrium ionisation models depending on the position. In the two-component model one emission component represents the shocked ISM and the other the shocked ejecta. Results: We detect enhanced element abundances, in particular for Si and Fe, in and around the Lobe. There is one particular region next to the Lobe with a high Si abundance of 3.3 (2.6 - 4.0) times the solar value. This is the first, unequivocal detection of ejecta in CTB 109. Conclusions: The new Chandra data confirm that the Lobe was created by the interaction of the SNR shock and the supernova ejecta with dense and inhomogeneous medium in the environment of SNR CTB 109. The newly calculated age of the SNR is t ~ 1.4 x 10^4 yr.