Astronomers often come up with strange names for things we've found. We have the "Big Bang", "Dark Energy" and even the "Atoms for Peace Galaxy". Usually these names have at least a passing resemblance to the thing they refer to. But today's addition, the "Death Star Galaxy," (see the press release) mystifies me completely. The pictures (above) don't look like the Death Star, the galaxy and its black hole are not stars, and it's much larger than a small moon. ("That's no galaxy -- that's a space station" just doesn't have the same ring to it.) The best guess I can have is that one galaxy appears to be shooting something like a laser beam at another galaxy.
That being said, what's the hubbub about?
What we see in the above image is a radio galaxy with the catalog name 3C321. The galaxy is far away, about 1.2 billion light years from Earth! When we look at the galaxy with Hubble, we actually see two galaxies that are colliding. Both galaxies have gigantic black holes at their centers, and the collision is sending tons of gas and dust in toward the black holes. Much of that gas and dust is swallowed by the black hole, but some of it is accelerated to high speeds and shot off in a jet that stretches nearly a million light-years in length.
Today's news is about a detailed study of these galaxies, using radio waves, optical light, ultraviolet light, and X-rays. Combining all these images gave the astronomers an unprecedented look at what is going on in a pair of colliding galaxies.
And that look resulted in a surprise. The jet from one of the black holes just happens to be pointed at the other galaxy, and the energetic particles in the jet are blasting through the poor target galaxy! Well, that's an overstatement. The jet seems to be hitting the second galaxy, and it is being deflected, much like a jet of water from a hose can bounce off of a car, causing the water stream to change both shape and direction. So, the second galaxy seems to be in no danger of being blasted apart into a million pieces.
This study is important, because some astronomers think that jets such as these may be important in explaining why we don't see stars forming in clusters of galaxies. The thought is that these jets may be powerful enough to evaporate all of the gas that stars form out of. Maybe, just maybe, this "Death Star Galaxy" can help us test that idea.
(For information on how the real Death Star works, check out this article.)