Yet the boffins don't know why... and when they work it out, it might be too late...

NASA's Chandra X-ray Observatory has revealed new evidence that extremely hot gas exists in a large region at the center of the Milky Way. The intensity and spectrum of the high-energy X-rays produced by this gas present a puzzle as to how it is being heated. ...an irregular, diffuse glow from a 10-million-degree Celsius gas cloud, embedded in a glow of higher-energy X-rays with a spectrum characteristic of 100-million-degree gas. "The best explanation for the Chandra data is that the high-energy X-rays come from an extremely hot gas cloud, ...This would mean that there is a significant shortcoming in our understanding of heat sources in the center of our Galaxy." "There is no known class of objects that could account for such a large number of high-energy X-ray sources at the Galactic center," said Fred Baganoff of the Massachusetts Institute of Technology (MIT) in Cambridge, a coauthor of the study.

Source: Chandra@Harvard