Astronomers have seen a distant galaxy begin to die in a major breakthrough in our understanding of the cosmos.
Galaxies begin to “die” when they cease to form stars. Astronomers have observed a large variety of such dead galaxies scattered throughout the universe – but could not say exactly why.
Now astronomers have gained a clear view of such a spectacular event and hope that it can shed the process that causes galaxies to become extinct.
The observed galaxy loses about 10,000 Suns annually, which means that the fuel is scarce to make new stars. It has now lost almost half of its gas, and because it still creates stars hundreds of times faster than our own Milky Way, it will use up the surplus in a few tens of millions of years and die as it does.
Because the galaxy is 9 billion light-years away, astronomers actually look at events that happened in the relative youth of the universe, when the cosmos was only 4.5 billion years old.
Astronomers think that the dramatic death was caused by a collision with another galaxy, which could possibly change our understanding of the events.
While the two galaxies collided, they joined to create the one observed by astronomers and named ID2299. The evidence for the collision was found in the form of a “tidal tail” – a long stream of stars and gas extending into interstellar space.
Such clues are usually too dim to be seen in distant galaxies. But the researchers accidentally grabbed it just as it was being launched and were therefore able to identify it.
Deaths of galaxies occur when their star-forming material is thrown into space, leaving it without the material needed to make new stars. Until now, most astronomers believed that this was due to the winds that erupt when stars form, and the black holes that sit in the center of the galaxy.
However, new research suggests that such collisions could also kill them.
The new paper also suggests that the two events can be easily confused: if gas emissions are caused by mergers and left untouched, it could look similar to the deaths caused by winds. As such, previous research that had apparently pointed to winds could have actually observed all the teasing, the researchers said, and previous work may need to be re-evaluated.
The research is reported in a new paper, ‘A Titanic interstellar medium ejection from a massive galaxy at z = 1.4’, published in Natural Astronomy.