Montage of Chandra X-ray and optical images of elliptical galaxies
Credit:NASA/CXC/U. Ohio/T.Statler & S.Diehl; Optical: DSS

Stirring the Drink

Elliptical galaxies were at one time thought to be rather boring objects. Because they lack large amounts of gass and dust they have little star formation activity, and they don't contain any really massive stars which make things more exciting by exploding once in a while. But new observations reveal that the hidden life of ellipticals is more interesting than meets the eye. The montage above compares Chandra X-ray Observatory images (blue) to optical images (grey) of a number of elliptical galaxies. The shape of the galaxies seen in the X-ray images is a lot different than the optical shape of the galaxies. This means that the hot gas, which produces the X-ray emission is not aligned with the distribution of stars which produce the optical light. Astronomers believe that the distribution of hot gas is produced by occasional explosions produced by a supermassive black hole lurking inside each elliptical.



Page Author: Dr. Michael F. Corcoran