Death of galaxy: Galactic collision spews gases equal to 10,000 suns a year

The Milky Way Galaxy that houses Earth is just over 13 billion years old. Still, in its youth, the galaxy has several billion years more to go. However, not all galaxies are that lucky. Astronomers have now discovered a dying galaxy as it loses its ability to form new stars. 

The merging galaxy formed 4.5 billion years ago is dubbed ID2299 and is ejecting gases equivalent to 10,000 Suns-worth of gas a year, rapidly losing its fuel core. 

The research published in Nature Astronomy titled “A titanic interstellar medium ejection from a massive starburst galaxy" suggests that the event was triggered by a galactic collision between two galaxies nine billion years into the past. 

Annagrazia Puglisi, lead researcher on the study, from the Durham University said that “This is the first time we have observed a typical massive star-forming galaxy in the distant universe about to die because of a massive cold gas ejection." The university in a statement said that the rate at which the gas is being expelled from ID2299 is too high to have been caused by the energy created by a black hole or starburst as seen in previous studies.

Atacama Large Millimeter/submillimeter Array (ALMA) — a state-of-the-art telescope to study light from some of the coldest objects in the Universe.

The new observation was done by the Atacama Large Millimeter/submillimeter Array (ALMA). According to the European Southern Observatory, "the clue that pointed the scientists towards this scenario was the association of the ejected gas with a tidal tail." The tidal tails, according to scientists, are streams of stars and gas extending into interstellar space that result when two galaxies merge and are largely faint in appearance.   

Most astronomers believe that winds caused by star formation and the activity of black holes at the centres of massive galaxies are responsible for launching star-forming material into space, thus ending galaxies’ ability to make new stars.

The study maintains that the observations provide compelling evidence that this is not a feedback-driven wind, but rather material from a merger that has been probably tidally ejected. 

“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar,” the observatory quoted study co-author Emanuele Daddi of CEA-Saclay as saying. “This might lead us to revise our understanding of how galaxies die,” Daddi adds.

According to the team, the discovery was made by chance while they were studying the dataset of galaxies observed by ALMA to study the properties of cold gas in more than 100 far-away galaxies. Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution, the team added. 

The team will now explore the connections between the stars and gas in ID2299, shedding new light on how galaxies evolve.