April 19, 2007 — Mysterious invisible "ghost spirals" observed in a nearby galaxy appear to be gigantic super-hot shockwaves, say astrophysicists.
The ghostly spiral arms of galaxy M106 were first detected in radio waves, contain no stars, and do not match up with the curved starry arms of the galaxy as seen by telescopes in visible light.
But new observations of M106's "anomalous arms" confirm they are the result of two gigantic jets blasting at a strange angle from the galaxy's central supermassive black hole.
"All you see is gas that is heated by shock waves," said astrophysicist Andrew Wilson of University of Maryland, referring to what the ghost arms are made of.
Because M106 is a relatively nearby galaxy — just 23.5 million light years away — new technology has allowed astronomers to continually improve their measurements of what's happening around M106's black hole and in its arms.
A few years ago, astronomers using the super-high resolution array of radio telescopes called the Very Long Baseline Array (VLBA) were finally able to measure the angle of those black hole jets roaring out of the core of M106, said Lincoln Greenhill of the Harvard-Smithsonian Center for Astrophysics. His team made the VLBA observations.
"The innovation now is recognizing the orientation of jets in three dimensional space," Greenhill told Discovery News. "This ends up blasting away the assumption that galaxies are flat."
