For the first time, astronomers have witnessed the death of a distant galaxy, which they describe as a “truly extreme event”. When all the stars in a galaxy die and no new stars form, the galaxy itself will cease to exist. This happens when all the galactic gas is ejected, making new star formation impossible.
In a paper published in the January 11, 2021 issue of the journal Nature Astronomy, scientists have detected this rare phenomenon for the first time.
The starburst galaxy numbered ID 2299 is about 9 billion light-years from Earth. So when astronomers happened to observe it, they were looking at a universe that is about 4.5 billion years old.
Astronomers say ID2299 loses about 10,000 solar masses of galactic gas per year, which rapidly depletes the material needed to form new stars. Such a staggering dissipation of galactic gas appears to be caused by the violent collisional merger of the two galaxies, which eventually merged to become ID2299.
Currently, galaxies are forming stars hundreds of times faster than the Milky Way, which further depletes their remaining supply of valuable galactic gas. As a result, ID2299 is expected to die quickly in a matter of tens of thousands of years.
In a statement from the European Southern Observatory, Annagrazia Puglisi, lead author of the paper, said: “This is the first time we have observed a typical giant star-forming galaxy in the far reaches of the universe going ‘green’ as a result of ejecting large amounts of galactic gas. of galactic gas to ‘death’.”
Astronomers believe that the appearance is the result of galaxy mergers because they can see rare “tidal tails” that are not normally seen in distant galaxies. Astronomers believe that this elongated stream of stars and gas is a direct result of galactic mergers. Although they observed the galaxies for only a few minutes, it was enough to spot the elusive tidal tails.
“Our study shows that mergers can produce gas jets, and that galactic winds and tidal tails look similar,” said Emanuele Daddi, one of the paper’s co-authors. “This could lead us to change our understanding of the ‘death’ of galaxies.”
If the research team is correct that galaxy mergers lead to huge losses of galaxy gas, they will need to reconsider previous theories about how galaxies form and evolve and how they die. Other theories suggest that galactic winds caused by active black holes or intense star formation are responsible for such deaths.
Dr. Jeremy Fensch, one of the paper’s co-authors, said, “Studying this single event reveals the possibility that such events may be widespread and that many galaxies have suffered this ‘gravitationally induced loss of galactic gas,’ including misinterpreting many past observations.” “This could have a huge impact on our understanding of what really shapes galaxy evolution.”
Puglisi echoed the significance of this major result, saying, “I am delighted to have discovered such a unique galaxy! I am eager to learn more about this strange object because I am convinced that there is some important information to learn about the evolution of distant galaxies.”
The surprising discovery was made by chance while the team was examining the results of a galaxy survey made by the Atacama Large Telescope Array (ALMA), designed to study the gas properties of galaxies in more than a hundred distant galaxies.ALMA observed ID2299 for only a few minutes, but collected enough data to study galaxies and their tidal tails.
Chiara Circosta, one of the paper’s co-authors, said, “ALMA reveals the mechanism by which star formation stops in distant galaxies. Witnessing such a massive disruption event adds significance to the complex puzzle of galaxy evolution.”
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