Suzaku Observations across the Cygnus Loop from the Northeastern to the Southwestern Rim

TL;DR

This study used Suzaku observations to analyze the spatial distribution of ejecta and swept-up matter in the Cygnus Loop, revealing asymmetries and estimating the supernova progenitor mass.

Contribution

First detailed Suzaku-based spatially resolved spectral analysis of the entire Cygnus Loop from NE to SW rim, identifying ejecta distribution asymmetries and shell thickness.

Findings

Ejecta of O, Ne, Mg are more in NE; Si and Fe are more in SW.

The swept-up matter shell is very thin in the SW region.

Estimated progenitor mass of 12-15 solar masses for the supernova.

Abstract

We have observed the Cygnus Loop from the northeast (NE) rim to the southwest (SW) rim using Suzaku in 10 pointings that is just north of previous XMM-Newton observations. The observation data obtained were divided into 45 rectangular regions where the width were configured so that each region holds 8000$-$12000 photons. The spectrum acquired from each region was fitted either with one-kTe-component non-equilibrium ionization (NEI) model or with two-kTe-component NEI model. The two-kTe-component model yields significantly better fit in almost all the non-rim regions. Judging from abundances and flux, the high-kTe-component (0.4$-$0.8keV) must be the ejecta origin, while the low-\kTe-component ($\sim$0.3keV) comes from the swept-up matter. We found that swept-up matter shell is very thin in just southwest of center of the Loop. Together with previous observations, we estimate the diameter of this thin shell region to be $1^{\circ}$. We also found that the ejecta distributions were asymmteric to the geometric center: the ejecta of O, Ne and Mg were distributed more in the NE, while the ejecta of Si and Fe were distributed more in the SW of the Cygnus Loop. We calculated the masses for various metals and estimated the origin of the Cygnus Loop as the 12-15M$_\odot$ core-collapse explosion.