Astronomers have, for the first time, witnessed 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 no longer form, the same galaxy ceases to exist. This happens when all the gas is expelled from the galaxy, 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 recently using the Atacama matrix of millimeters / submillimeters of telescopes in Chile.
The light from the galaxy ID2299 has taken about nine billion years to reach Earth. Therefore, when astronomers observed it by chance, they witnessed the universe as it appeared only 4.5 billion years ago.
Astronomers say ID2299 loses 10,000 suns of gas each year, quickly depleting the fuel needed to form new stars. This startling gas release appears to be the result of two galaxies colliding violently and merging to create ID2299.
Today, the galaxy also forms stars at a rate hundreds of times faster than the Milky Way, consuming the rest of its precious gas supply. Therefore, ID2299 is expected to die relatively soon, in a few tens of thousands of years.
Southern European Observatory
“This is the first time we have observed a typical massive star-forming galaxy in the distant universe about to ‘die’ due to a massive expulsion of cold gas,” lead author Annagrazia Puglisi said in a communiqué.
Astronomers believe the phenomenon is the result of the fusion of galaxies because they were able to witness a rare “tidal tail,” usually too faint to see it in distant galaxies. This elongated stream of stars and gas, astronomers suggest, is the direct result of galactic fusion.
They only observed the galaxy for a few minutes, but it was enough to detect the elusive tidal tail.
“Our study suggests that gas melts can cause ejections and that winds and tidal tails may look very similar,” says Emanuele Daddi, co-author of the study. “This could lead us to review our understanding of how ‘galaxies die’.”
If astronomers are right in saying that the fusion caused a massive loss of gas, they will have to reconsider previous theories about how galaxies form and evolve and how they die. Other theories have suggested that wind from active black holes or intense star formations is responsible for these deaths.
“The study of this unique case revealed the possibility that such events would not be unusual and that many galaxies would suffer from this ‘elimination of gravitational gases’, including misinterpreted past observations,” said the co-author. Dr. Jeremy Fensch.
“This can have huge consequences for our understanding of what actually shapes galaxy evolution.”