For the first time, scientists are able to observe the death of a galaxy, which happens when it loses its ability to form stars. In a paper published in Nature Astronomy journal, a team of fifteen scientists observed that the ID2299 galaxy ejected half of the gas it uses to form stars. This observation was captured in Chile by the Atacama Large Millimeter/submillimeter Array of telescopes.
The study found that the galaxy is losing 10,000 suns-worth of gas every year, which is reducing the fuel it needs to form stars by removing 46 percent of the ID2299's total cold gas so far.
The research mentioned that it has taken about nine billion years for the light from the ID2299 galaxy to reach Earth, which means that astronomers are observing how did it happen when the universe was only 4.5 billion years old. At this point, the universe is estimated to be 14 billion years old.
Lead author of the study, Annagrazia Puglisi from Centre for Extragalactic Astronomy at Department of Physics, Durham University in UK said that this is the first time they have observed a typical massive star-forming galaxy in the distant universe about to 'die' because of a gigantic cold gas ejection.
A galaxy caught dying? @ALMAObs sees a distant galaxy ejecting nearly half of its star-forming gas at a rate equivalent to 10,000 Suns worth of gas a year, causing the galaxy to lose its fuel to make new stars. Credit: @ESO /M. Kornmesser https://t.co/JXduGUEoya pic.twitter.com/QHqfoNmTCR— ESO (@ESO) January 11, 2021
However, scientists say that the galaxy is still quickly forming stars at a rate that is hundreds of times faster than our own Milky Way, which will use up the rest of its gas. This will eventually cause ID2299 to die in a few tens of million years, predicts the recent research.
The study has also speculated that the possible reason why the galaxy is dying is because of a collision with another galaxy, which eventually merged to create ID2299. What gives scientists the reason to speculate this reason is the presence of a long stream of gas and stars that extend out into space after two galaxies come together in a collision. This stream is also known as a tidal tail.
These tidal tails are too vague to be seen in such a faraway galaxy, but the astronomers in this study were able to observe the bright tail as it was extending out into space. Study co-author Emanuele Daddi, who is also an astronomer at the Saclay Nuclear Research Centre in France, said that their study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear remarkably similar. This discovery might lead scientists to revise their understanding of how galaxies die.