The Plasma Structure of the Southwestern Region of the Cygnus Loop with the XMM-Newton Observatory

Abstract

We observed the southwestern region of the Cygnus Loop in two pointings with \textit{XMM-Newton}. The region observed is called the "blow-out" region that is extended further in the south. The origin of the "blow-out" is not well understood while it is suggested that there is another supernova remnant here in radio observation. To investigate the detail structure of this region in X-ray, we divided our fields of view into 33 box regions. The spectra are well fitted by a two-component nonequilibrium ionization model. The emission measure distributions of heavy elements decrease from the inner region to the outer region of the Loop. Then, we also divided our fields of view into 26 annular sectors to examine the radial plasma structure. Judging from metal abundances obtained, it is consistent with that the X-ray emission is the Cygnus Loop origin and we concluded that high-$k{T}_e$ component ($\sim$0.4 keV) originates from the ejecta while low-$k{T}_e$ component ($\sim$0.2 keV) is derived from the swept-up interstellar medium. The flux of low-$k{T}_e$ component is much less than that of high-$k{T}_e$ component, suggesting the ISM component is very thin. Also, the relative abundances in the ejecta component shows similar values to those obtained from previous observations of the Cygnus Loop. We find no evidence in X-ray that the nature of the "blow-out" region originated from the extra supernova remnant. From the ejecta component, we calculated the masses for various metals and estimated the origin of the Cygnus Loop as the core-collapse explosion rather than the Type Ia supernova.

arXiv comment10 pages, 28 figures, accepted for publication in the Astrophysical Journal

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• The Ejecta Distributions of the Heavy Elements in the Cygnus Loop
• Line-of-sight Shell Structure of the Cygnus Loop
• Global Far-Ultraviolet Properties of the Cygnus Loop
• The Abundance Inhomogeneity in the Northern Rim of the Cygnus Loop
• The origin of the X-ray emitting plasma in the eastern edge of the Cygnus Loop
• Discovery of a Pulsar Wind Nebula Candidate in the Cygnus Loop
• New continuum and polarization observations of the Cygnus Loop with FAST II. Images and analyses
• On the Hα faintness of the North Polar Spur