The Detection of X-Rays from the Hot Interstellar Medium of the Large Magellanic Cloud

We present a comprehensive reanalysis of the Einstein Observatory imaging survey of the Large Magellanic Cloud. Techniques necessary for the study of faint diffuse X-rays, including the decontamination of images from solar scattered X-rays, are described in detail. A discrete source search of a ~ 37 deg^2^ region in the vicinity of the LMC reveals 105 sources, 33 of which are reported here for the first time. About half of the sources are clearly identified with objects in that galaxy, while the remainder are shown to be predominantly foreground stars and background AGNs. Subtraction of all discrete emitters reveals extensive diffuse X-ray emission associated with the LMC. The spectrum of this emission is well fitted by an optically thin thermal plasma with temperatures ranging from ~ 2 x 10^6^ K in the western part of the galaxy to ~ 10^7^ K in the vicinity of the active star formation complex near 30 Doradus. An anticorrelation of H I and diffuse X-rays on scales of <~ 1 kpc is consistent with a picture in which superbubbles of hot gas are created in the neutral ISM by the combined action of stellar winds and supernovae in massive stellar associations. Over a substantial fraction of the galaxy, the hot ISM is seen to have an emissivity and a pressure significantly in excess of that in the medium surrounding the Sun. Estimates of the cooling and heating rates for the hot gas suggest that a substantial fraction of the energy input from stellar winds and SNs either radiates in other wavelength bands or leaves the galaxy in the form of a wind. The prospects for using the LMC as a testbed for global ISM models is briefly discussed.