Death Of Galaxy Witnessed By Astronomers For First Time Ever
Astronomers have gained an ‘important piece to the complex puzzle of galaxy evolution’ after observing the death of a distant galaxy for the first time ever.
Using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile, scientists witnessed the ID2299 galaxy as it ejected almost half of the gas it uses to form stars.
The galaxy is losing approximately 10,000 suns-worth of gas each year, meaning it is constantly diminishing the fuel it needs to form stars. It has removed 46% of the galaxy’s total cold gas so far, and while it continues to form stars at a rate hundreds of times faster than the Milky Way, in doing so it will use up the rest of the gas in the galaxy.
As galaxies die when their stars stop forming, ID2299 will die in millions of years.
The universe is currently an estimated 14 billion years old, but as the light from ID2299 has taken roughly nine billion years to reach Earth, the astronomers glimpsed it as it appeared when the universe was only 4.5 billion years old.
Annagrazia Puglisi, lead study researcher and postdoctoral research associate from Durham University in the UK and the Saclay Nuclear Research Centre in France, said in a press release this is the first time astronomers have observed ‘a typical massive star-forming galaxy in the distant Universe about to ‘die’ because of a massive cold gas ejection’.
In the study, published in the journal Nature Astronomy, the researchers speculated that the galaxy’s death was caused by a collision with another galaxy, which merged to create ID2299.
At the time of the observation, researchers were working on a different survey of cold gas in distant galaxies, so while they only observed ID2299 for a few minutes they managed to spot a tidal tail – a stream of gas and stars that extend out into space after two galaxies collide.
Emanuele Daddi, study co-author and astronomer at the Saclay Nuclear Research Centre, explained:
Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar. This might lead us to revise our understanding of how galaxies ‘die’.
Scientists have previously believed that star formation came to an end due to winds created by their formation and active black holes at the centres of giant galaxies. It has been suggested that the winds sent the material needed to form the stars hurtling out into space, ultimately putting a stop to formation.
However, if the merger of two galaxies was the cause of the loss of gas, astronomers may need to reconsider what they believe about the end of star formation in galaxies.
Chiara Circosta, study co-author and researcher at University College London, said the observation has ‘shed new light on the mechanisms that can halt the formation of stars in distant galaxies’.
Circosta added: ‘Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution.’
Future observations of ID2299 as it dies could reveal more about the gas it is ejecting.
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