Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered a massive starburst galaxy with a tail of star-forming gas in the distant Universe. Named ID2299, the galaxy is ejecting 46% of its star-forming gas at a startling rate of 10,000 solar masses per year. The researchers believe that this spectacular event was triggered by a collision with another galaxy.
An artist’s impression of the ID2299 galaxy. Image credit: M. Kornmesser / ESO.
ID2299 is located approximately 9 billion light-years away from Earth; we see it when the Universe was just 4.5 billion years old.
The gas ejection in the galaxy is happening at a rate equivalent to 10,000 solar masses per year.
Because ID2299 is also forming stars very rapidly, hundreds of times faster than our Milky Way, the remaining gas will be quickly consumed, shutting down the galaxy in just a few tens of million years.
The event responsible for the spectacular gas loss is a collision between two galaxies, which eventually merged to form ID2299.
“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,” said lead author Dr. Annagrazia Puglisi, an astronomer at Durham University and the Saclay Nuclear Research Centre.
Most astronomers believe that winds caused by star formation and the activity of black holes at the centers of massive galaxies are responsible for launching star-forming material into space, thus ending galaxies’ ability to make new stars.
However, the discovery of ID2299 suggests that galactic mergers can also be responsible for ejecting star-forming fuel into space.
“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar,” said co-author Dr. Emanuele Daddi, an astronomer at CEA-Saclay.
“I was thrilled to discover such an exceptional galaxy,” Dr. Puglisi said.
“I was eager to learn more about this weird object because I was convinced that there was some important lesson to be learned about how distant galaxies evolve.”
ID2299 had been observed by ALMA for only a few minutes, but the powerful observatory allowed the team to collect enough data to detect the galaxy and its ejection tail.
“ALMA has shed new light on the mechanisms that can halt the formation of stars in distant galaxies,” said co-author Dr. Chiara Circosta, an astronomer at University College London.
“Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution.”
The discovery of ID2299 is described in a paper published this week in the journal Nature Astronomy.
_____
A. Puglisi et al. A titanic interstellar medium ejection from a massive starburst galaxy at redshift 1.4. Nat Astron, published online January 11, 2021; doi: 10.1038/s41550-020-01268-x
