Jan 13, 2024 at 3:59 PM Update: 2 hours ago
The formation of stars has not changed in the past ten billion years, astronomers note with surprise. According to them, it comes down to one thing: hot gas can or cannot cool down quickly. That is evident from it largest research to star formation someday.
“What’s surprising here is that there are a lot of things that could have influenced star formation over the last ten billion years,” said lead researcher Michael Calzadilla of the Massachusetts Institute of Technology (MIT).
According to him, the main driver behind star formation in large galaxies comes down to one thing: whether or not the hot gas around them can cool quickly enough.
Clusters of galaxies are the largest objects in the universe. These are held together by gravity and contain enormous amounts of hot gas. The mass of that hot gas is gigantic: several times the total mass of all stars that occur in galaxy clusters. That hot gas turns out to be the linchpin in the process of star formation.
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Threshold value appears to be decisive for star formation
The researchers studied the brightest cluster galaxies in the universe. These bright galaxies are very massive and are located at the center of 95 galaxy clusters 3.4 to 9.9 billion light-years away from Earth.
The team discovered that star formation in those galaxies is triggered when the amount of movement in the hot gas falls below a critical threshold. The hot gas inevitably cools below that threshold and forms new stars. This threshold value therefore indicates whether or not stars are formed.
“It’s impressive to think that a single number tells us whether billions of stars and planets have formed in these massive galaxies, going back ten billion years,” the researchers say.
‘Cosmic noon’ actually still exists
Previous results suggested that factors other than the cooling of hot gas could play a larger role in star formation.
Ten billion years ago, during a period astronomers call “cosmic noon,” collisions and mergers of galaxies into clusters became much more common. Stars were also formed faster and black holes in a galaxy attracted material much faster.
Still, the star formation now studied looks remarkably similar to that from the cosmic noon. “Although the universe looked very different then, the basis of star formation, the critical threshold, has always remained the same in these galaxies.”
2024-01-13 14:59:12
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