Astronomers have witnessed, for the first time, the death of a distant galaxy, which they describe as a “truly extreme event.”
When all the stars in a galaxy die and new ones do not form, the galaxy itself ceases to exist. This happens when all the gas in the galaxy is released, making it impossible for new stars to form.
According to a study published Monday in the journal Nature Astronomy, scientists were “delighted” to be able to capture this rare phenomenon using the recent Atacama Large Millimeter / submillimeter Array of Chilean telescopes.
It took about nine billion years for light from galaxy ID2299 to reach Earth. So when astronomers observed it by chance, they witnessed the universe as it appeared just 4.5 billion years ago.
Astronomers say that ID2299 loses 10,000 suns of gas each year – quickly depleting the fuel needed to form new stars. This amazing release of gas appears to be the result of two galaxies colliding violently and merging together to create ID2299.
Today, the galaxy forms stars hundreds of times faster than the Milky Way – consuming the rest of precious gas sources. Because of this, ID2299 is expected to die relatively soon, in just a few tens of thousands of years.
Southern European Observatory
“This is the first time we have seen a massive galaxy forming stars in the distant universe about to ‘die’ from a massive cold gas ejection,” lead author Annagrazia Puglisi said in a statement.
Astronomers believe that the phenomenon is the result of the fusion of galaxies, because they managed to witness a rare “tidal tail”, usually too weak to be seen in distant galaxies. This elongated flow of stars and gases, astronomers suggest, is the direct result of galactic fusion.
They only observed the galaxy for a few minutes, but it was enough to observe the evasive tidal tail.
“Our study suggests that gas leaks can be produced by fusions and that tidal winds and tails can look very similar,” says study co-author Emanuele Daddi. “This could lead us to rethink our understanding of how ‘galaxies die’.”
If astronomers are right that the fusion led to massive gas loss, they will have to reconsider previous theories about how galaxies form and evolve – and how they die. Other theories have suggested that wind in active black holes or intense star formations is responsible for such deaths.
“Studying this unique case has revealed the possibility that this type of event is not at all unusual and that many galaxies have suffered because of this ‘gravitational removal of gas’, including misinterpreted observations from the past,” said co-author Dr. Jeremy Fensch.
“This could have huge consequences for our understanding of what actually shapes galaxy evolution.”