Astronomers have for the first time witnessed the death of a distant galaxy, which they describe as a ‘real extreme event’.
When all the stars in an galaxy die, and new ones no longer form, the galaxy itself ceases to exist. This occurs when all the gases are expelled from the galaxy, making it impossible to form new stars.
According to a study published Monday in the journal Nature Astronomy, scientists were “delighted” to capture this rare phenomenon recently using the Atacama Large Millimeter / submilimeter Array of Telescopes in Chile.
It took about nine billion years before the light of the star-galaxy ID2299 reached Earth. When astronomers observed it by chance, they saw the universe when it was only 4.5 billion years old.
Astronomers say that ID2299 loses 10,000 suns of gas each year, which quickly needs fuel to form new stars. This surprising release of gas appears to be the result of two galaxies violently colliding and merging to create ID2299.
The galaxy is also currently forming stars at a rate hundreds of times faster than the Milky Way – utilizing the rest of its precious gas supply. As a result, ID2299 is expected to die relatively soon within a few tens of thousands of years.
European Southern Observatory
“This is the first time we are observing a massive star-forming galaxy in the distant universe that is going to die due to a massive emission of cold gas,” lead author Annagrazia Puglisi said in a statement.
Astronomers believe that the phenomenon is the result of galaxies that have fused because they could see a rare ‘tidal tail’, usually too faint to see in distant galaxies. This elongated stream of stars and gas is, according to astronomers, the direct result of the merger.
They observed the galaxy for only a few minutes, but it was enough to spot the elusive tyrant.
“Our study suggests that gas emissions can be produced by mergers and that wind and tides can look very much the same,” says study co-author Emanuele Daddi. “It could lead us to revise our understanding of how galaxies die.”
If the astronomers are correct that the merger led to the great loss of gas, they will have to consider in advance theories about how galaxies form and develop – and how they die. Other theories have suggested that winds from active black holes or intense star formations are responsible for such deaths.
“The study of this single case revealed the possibility that this type of event would not be unusual at all and that many galaxies suffered from this ‘gravity gas removal’, including misinterpretations of previous observations,” said dr. Jeremy Fensch said.
“It could have major implications for our understanding of what the evolution of galaxies actually is.”