The XMM-Newton view of the DEM L36 superbubble in the Large Magellanic Cloud

Abstract

We present the first multi-wavelength analysis of the DEM L36 superbubble in the Large Magellanic Cloud. We compare the DEM L36 superbubble with other Galactic and Magellanic Cloud superbubbles. We use data from XMM-Newton, supplemented by data from the Magellanic Cloud Emission Line Survey, the Dark Energy Camera Magellanic Cloud Emission Line Survey, the Spitzer Space Telescope, and the Australia Telescope Compact Array. We perform a multi-wavelength morphological analysis to understand the shape and structure of the superbubble and X-ray spectral analysis to derive physical parameters of the hot gas. We find significant X-ray emission in DEM L36, dominated by a central bubble region mostly confined by a thin H$α$ filamentary shell. This has two distinct blowout regions to the east and west, with a possible smaller blowout in the south. Spectral analysis shows the X-ray emission is well fit with a thermal plasma model in collisional ionisation equilibrium with a temperature of $kT=0.17~(0.16-0.18)$ keV and unabsorbed luminosity $L_{X~(0.5-7.0~\mathrm{keV})}=3.62\times 10^{35}$erg s$^{-1}$. Unlike other LMC superbubbles, we find no clear powering cluster at the centre, though relatively small clusters near the edge are likely supplying the mechanical input at the present epoch. We use photometric data of these clusters to estimate cluster masses, ages, and mechanical inputs to compare with the energy stored in the superbubble. We find that these clusters have supplied more energy over their lifetime than is currently observed in the superbubble, indicative of the so-called growth rate discrepancy problem. It is likely the DEM L36 superbubble was initially shaped by a central massive stellar population that has since dispersed and largely lost to supernovae, with smaller clusters at the edges of the swept-up shell being currently supplying the energy input.