A BeppoSAX observation of the X-ray pulsar 1E 2259+586 and the supernova remnant G109.1-1.0 (CTB 109)

TL;DR

This study presents BeppoSAX observations of the 7-second X-ray pulsar 1E 2259+586 and its associated supernova remnant G109.1-1.0, revealing spectral components, pulse profiles, and the remnant's physical properties consistent with a young, mildly enriched circumstellar environment.

Contribution

First detailed spectral and timing analysis of 1E 2259+586 and G109.1-1.0 using BeppoSAX data, confirming low-energy spectral components and remnant's age and composition.

Findings

Pulse period of 6.978914 s with near constant spin-down.

Double peaked pulse profile with energy-independent shape.

Remnant's plasma temperature of 0.95 keV and age of ~3000 years.

Abstract

The 7 s X-ray pulsar 1E2259+586 and the supernova remnant (SNR) G109.1-1.0 (CTB 109) were observed by BeppoSAX in 1996 November. The pulse period of 6.978914 +/- 0.000006 s implies that the source continues its near constant spin-down trend. The 0.5-10 keV pulse shape is characterized by a double peaked profile, with the amplitude of the second peak ~50% of that of the main peak. The pulse profile does not exhibit any strong energy dependence. We confirm the ASCA discovery of an additional low-energy spectral component from 1E2259+586. This can best be modeled as a 0.44 keV blackbody, but we cannot exclude that some, or all, of this emission arises from the part of the SNR that lies within the pulsar's extraction region. The spectrum of G109.1-1.0 is well fit with a non-equilibrium ionization plasma model with a best-fit temperature of 0.95 keV. The derived mass for the X-ray emitting plasma (~15-20 solar masses) and its near cosmic abundances imply that the X-ray emission comes mainly from mildly enriched, swept-up circumstellar material. The spectrum is strongly out of equilibrium with an ionization age of only 3000 yr. This age is in good agreement with that derived from hydrodynamic simulations of the SNR using the above X-ray temperature.