Astronomers Witness Whopper Galaxy Collision

Raver32 writes "A major cosmic pileup involving four large galaxies could give rise to one of the largest galaxies the universe has ever known, scientists say. Each of the four galaxies is at least the size of the Milky Way, and each is home to billions of stars. The galaxies will eventually merge into a single, colossal galaxy up to 10 times as massive as our own Milky Way. "When this merger is complete, this will be one of the biggest galaxies in the universe," said study team member Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics. The finding, to be detailed in an upcoming issue of Astrophysical Journal Letters, gives scientists their first real glimpse into a galaxy merger involving multiple big galaxies. "Most of the galaxy mergers we already knew about are like compact cars crashing together," Rines said. "What we have here is like four sand trucks smashing together, flinging sand everywhere.""

Comments

Its Galacta-mania IV!

[sizzzzlerz]

Its an four-way inter-galactic throw-down to determine the true Champion of the Universe!

Four galaxies enter. One galaxy leaves.

Re:One of the biggest in the universe?

[Anonymous Coward]

Your logic is flawed.

There are an infinite real numbers between 0 and 1 inclusive, but there is a largest element in the set (specifically, 1.0).

Likewise, even given an infinite set of galaxies, there can be a largest galaxy.

Re:4 way stop?

[drooling-dog]

What happens when the black holes at the center of each one collide? Glad you asked that question... Just read a couple of papers about that yesterday in the 29 June issue of Science. From one of the abstracts: It is normally assumed that after the merger of two massive galaxies, a SMBH [supermassive black hole] binary will form, shrink because of stellar gas dynamical processes, and ultimately coalesce by emitting a burst of gravitational waves... We report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years after the collision between two spiral galaxies. A massive, turbulant, nuclear gaseous disk arises as the a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than 1 million years as a result of the gravitational drag from the gas rather than from the stars. - Meyer et.al., Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers with Gas, Science 316,1874 (2007).

Re:We're in the middle of a galactic accident now

[Yusaku Godai]

This is definitely a cool idea. But it's just a myth. Take a look at that site--lots of wonky pseudo-science to be had. And I especially knew something was wrong when they started talking about the Mayan calendar and global warming.

At any rate, take a look at the original press release that was misinterpreted to come up with this theory here: http://astsun.astro.virginia.edu/~mfs4n/sgr/
And take a look at a debunking here: http://www.badastronomy.com/bablog/2007/06/27/is-t he-sun-from-another-galaxy

And the wonkiness about the angle we see the Milky Way at from Earth is just plain bad math.

Re:Expanding Universe?

[Control Group]

Wrong scale. On the macroscopic scale - the same scale where the universe looks the same in all directions - everything is moving away from everything else. On smaller scales, of course, this isn't the case*. To see the "everything expanding" universe and the "everything homogenous" universe, you need to lower the granularity of your observations to the point that this sort of localized clustering isn't measurable. A good start would be to take Hubble's Ultra Deep Field image as your basic unit of observation (and that's still only 0.000008% of the area of the sky). In that image, only five of the objects visible (the ones with lens flare crosses) are stars, every other object is a galaxy. You can see the homogeneity of the universe in that image. Four of those galaxies colliding - even the four largest that are visible - wouldn't change the overall character of the image at all.

*Well, this may or may not be the case, depending on how well I understand the expansion of space. If the apparently-faster-than-light expansion of the early universe is, in fact, due to a combination of things flying apart and the space between them expanding, it's reasonable to think that space is still expanding. In which case, literally everything is moving apart from everything else, from the neutrons and protons in your average nucleus to galactic clusters. But I may be misunderstanding the expansion of space.