All that will happen to the Milky Way in about five billion years, when it merges with the Andromeda Galaxy. It turns out that the smaller Triangulum Galaxy will get involved, too. And, right now, the Milky Way is gobbling up dwarf spheroidal galaxies. But, it hasn’t affected our galaxy’s ability to make stars. So, why did SDSS J1448+1010 lose so much material in its merger that it went dormant?
SDSS J1448+1010 is a newly-dormant massive galaxy that’s nearing the completion of a merger with another galaxy. During the course of this merger, the force of gravity flung what amounts to nearly half of the system’s gas needed for star formation away from the galaxy, leaving it unable to form new stars.
This discovery sheds light on the processes that change galaxies. It also helps scientists to better understand their evolution. According to cosmologist and paper co-author Wren Suess, at the University of California Santa Cruz, the processes galaxies experience are under intense study. “When we look out at the Universe, we see some galaxies that are actively forming new stars, like our own Milky Way, and some that aren’t.
“While it’s pretty clear from this system that cold gas really can end up way outside of a merger system that shuts off a galaxy, the sample size of one galaxy tells us very little about how common this process is,” said David Setton, a graduate student in the department of physics and astronomy at the University of Pittsburgh and a co-author of the paper.
These new observations show that while there are well-understood ways to shut down star formation in a galaxy, astronomers haven’t found all of them. “Astronomers used to think that the only way to make galaxies stop forming stars was through really violent, fast processes, like a bunch of supernovae exploding in the galaxy to blow most of the gas out of the galaxy and heat up the rest,” said Spilker. “Our new observations show that it doesn’t take a ‘flashy’ process to cut off star formation.
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