Mystery of the Ghostly Spiral Arms of a Galaxy is Solved.

Astronomers seem to have answered the long-standing mystery of the two ghostly spiral arms in the galaxy M106:

By analyzing data from XMM-Newton, Spitzer, and Chandra, the team in Maryland have confirmed earlier suspicions that the ghostly arms represent regions of gas that are being violently heated by shock waves.

It has been previously suggested that the anomalous arms are jets of particles being ejected by a supermassive black hole in M106’s nucleus. But radio observations at the Very Large Array in New Mexico later identified another pair of jets originating in the core. "It is highly unlikely that an active galactic nucleus could have more than one pair of jets," says Yang.

Link | APOD