Diffuse X-ray emission from the superbubbles N 70 and N 185 in the Large Magellanic Cloud

TL;DR

This study analyzes diffuse X-ray emission from superbubbles N 70 and N 185 in the Large Magellanic Cloud using XMM-Newton data, revealing shock-heated gas and luminosities exceeding standard models, suggesting additional energy sources like supernovae.

Contribution

First detailed X-ray spectral and imaging analysis of N 70 and N 185 superbubbles, highlighting the need to include supernova contributions in models.

Findings

X-ray emission originates from shock-heated gas inside the optical shells.

X-ray luminosities are higher than predictions from standard models.

X-ray emission distribution varies between the two superbubbles.

Abstract

We present a study of the diffuse X-ray emission from superbubbles N 70 (DEM L301) and N 185 (DEM L25) located in the Large Magellanic Cloud, based on data from the XMM-Newton Satellite. We obtained spectra and images of these objects in the soft X-ray energy band. These X-ray spectra were fitted by a thermal plasma model, with temperatures of $2.6 \times 10^{6}$ K and $2.3 \times 10^{6}$ K, for N 70 and N 185, respectively. For N 70, images show that X-ray emission comes from the inner regions of the superbubble, when we compare the distribution of the X-ray and the optical emission; while for N 185, the X-ray emission is partially confined by the optical shell. We suggest that the observed X-ray emission is caused by shock-heated gas, inside of the optical shells. We also obtained X-ray luminosities which exceed the values predicted by the standard analytical model. This fact shows that, in addition to the winds of the interior stars, it is necessary to consider another ingredient in the description, such as a supernova explosion, as has been proposed in previous numerical models.