An unusually mature galaxy found in the newborn universe
US, WASHINGTON (ORDO NEWS) — It seems that astronomers will have to rethink their ideas about the birth of galaxies. And the reason for this is the recently discovered star system. When the age of the Universe was only 10% of the present, she was already a fully-formed and adult “lady.” According to generally accepted theories, the galaxy should not have reached such maturity.
The discovery is described in a scientific article published in the journal Nature.
The stormy childhood of galaxies
According to most models, massive disk galaxies, such as the Milky Way, formed gradually. The first stars were lit in them already in the first hundreds of millions of years after the Big Bang (which happened 13.8 billion years ago). But to gain the current mass, it took them about six billion years. All this time, the mass of stellar systems has grown due to the absorption of neighboring galaxies and hot intergalactic gas.
Such a turbulent childhood leaves its mark on the face of the galaxy. During this period, it bears little resemblance to an ordered disk in which most stars revolve around the center of the system in one direction. Rather, it looks like a chaotic cloud in which the luminaries move wherever. This is what researchers usually see, observing the distant past of galaxies.
(It’s worth explaining that astronomers do not look into the early Universe with the help of a time machine. The fact is that the light of the most distant galaxies reaches the Earth’s telescopes for a very long time. Therefore, today we see them as they were billions of years ago, when it radiation was emitted.)
“Most galaxies that we find in the early universe, reminiscent of the train after the crash because they had been consistent and often disastrous merger [with other galaxies]”, – says the first author of the article Marcel Neeleman ( by Marcel Neeleman ) from the Institute of Astronomy Society Max Planck.
In recent years, alternative models have appeared in which disk galaxies form in just a billion years, and the main material for them is cold gas. But so far, these new theories have not had strong observational evidence.
System that was born an adult
Everything has changed thanks to the ALMA radio telescope . Researchers discovered the DLA0817g galaxy, which they unofficially called Wulf’s disk, in honor of the American astronomer Arthur Wolfe, who died in 2014.
This star system became the farthest galaxy in which it was possible to detect the rotation of the disk. According to observations, it rotates at a speed of 170 kilometers per second. The Milky Way disk rotates about the same speed.
Meanwhile, we now see DLA0817g as it was when the age of the Universe was only 10% of the current one. It is amazing that such a young system is an ordered rotating disk. This is not consistent with the traditional theories of multiple mergers, which we talked about above. But the models of fast galaxy formation from cold gas received unexpected confirmation.
“Previous research only hinted at the existence of these early rotating gas-rich disk galaxies. Now thanks to ALMA, we have unequivocal evidence that they existed already 1.5 billion years after the Big Bang,” says Nilman.
However, even for new theories, Wolfe’s drive is a problem. There is too much cold gas in it, and it spins too fast than follows from these models. So, it seems that nature again forced experts to make adjustments to their calculations.
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