Adding Depth to X-ray Maps

Abstract

X-ray maps of the heavens, constructed from satellite data, indicate that the solar system is surrounded by a bubble of hot plasma emitting soft x-rays. But they don't reveal how extensive the bubble is because they contain no distance information. Now, Q. Daniel Wang of Northwestern University is beginning to add depth to x-ray images. At last month's American Astronomical Society meeting, he described a technique he calls “x-ray shadowing” that uses warm, dense clouds of neutral gas that happen to waft through our galactic neighborhood as a kind of cosmic range finder. His first results have rekindled a debate about the distribution of hot plasmas throughout the Milky Way.