Soft X-ray Spectroscopy of the Cygnus Loop Supernova Remnant

TL;DR

This paper presents high-resolution soft X-ray spectroscopy of the Cygnus Loop supernova remnant using a novel instrument, revealing plasma conditions consistent with equilibrium models and previous observations.

Contribution

It introduces a new X-ray spectrograph setup and provides detailed spectral analysis of the Cygnus Loop, confirming equilibrium plasma conditions and elemental abundances.

Findings

Spectral features dominated by He-like triplet of O VII and sulfur lines.

Plasma temperature estimated at log(T)=6.2, consistent with previous data.

Emission driven by blast wave interactions with surrounding cavity walls.

Abstract

The Cygnus X-ray Emission Spectroscopic Survey (CyXESS) sounding rocket payload was launched from White Sands Missile Range on 2006 November 20 and obtained a high resolution spectrum of the Cygnus Loop supernova remnant in the soft X-rays. The novel X-ray spectrograph incorporated a wire-grid collimator feeding an array of gratings in the extreme off-plane mount which ultimately dispersed the spectrum onto Gaseous Electron Multiplier (GEM) detectors. This instrument recorded 65 seconds of usable data between 43-49.5 \AA in two prominent features. The first feature near 45 \AA is dominated by the He-like triplet of \ion{O}{7} in second order with contributions from \ion{Mg}{10} and \ion{Si}{9}-\ion{Si}{12} in first order, while the second feature near 47.5 \AA is first order \ion{S}{9} and \ion{S}{10}. Fits to the spectra give an equilibrium plasma at $\log(T)=6.2$ ($kT_e=0.14$ keV) and near cosmic abundances. This is consistent with previous observations, which demonstrated that the soft x-ray emission from the Cygnus Loop is dominated by interactions between the initial blast wave with the walls of a precursor formed cavity surrounding the Cygnus Loop and that this interaction can be described using equilibrium conditions.