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They find a twin of the Milky Way in the infancy of the Universe

2020-08-12T15:25:56.556Z


Galaxy SPT0418-47 was already a gigantic and stable object 1.4 billion years ago, 4.5 billion years earlier than you might expect.


12 billion years ago, when the universe was only 10% its current age and arguably in its infancy, the first galaxies had been around for a few hundred million years. The hydrogen clouds that emerged from the Big Bang had finally cooled down, and during the first billion years of the cosmos' existence the first stars and galaxies had begun to form. Astronomers expected that the extreme astrophysical processes and conditions of that early universe would give rise to galaxies very different from the current ones, hotter and more unstable, still affected by the mergers of galaxies and supernova explosions common at that time. However, in a work published today in the journal Nature, a group of researchers led from the Max-Planck Institute for Astrophysics in Garching, Germany, shows that, at least in some cases, surprises can be found in deep time.

To get close to one of those first galaxies, astronomers used the ALMA (Atacama Large Millimeter / submilimeter Array) radio telescope network, a set of 66 antennas designed to function as a single gigantic built at more than 5,000 meters high in the desert of Atacama (Chile). From there, they received the signal from a very distant object, from when the cosmos was only 1.4 billion years old (it is now 13,700). To his surprise, it was not chaotic and unstable but rather resembled the Milky Way, the galaxy in which we traverse the universe.

Until now it was thought that large galaxies form after violent mergers of smaller ones

"This result shows that the structures we observe in nearby spiral galaxies already existed 12,000 million years ago," Francesca Rizzo, first author of the Nature article, said in a statement from the European Southern Observatory . Although the galaxy, dubbed SPT0418-47, does not have the characteristic arms of the Milky Way, it does have a rotating disk and a galactic bulge, a feature not previously observed in galaxies of this period.

The finding is added to that of the Wolfe Disk, another galaxy similar to ours that already existed more than 12,000 million years ago. Their discovery, published in May this year in Nature , already showed the possibility that massive galaxies in the early universe could be stable. The most widely accepted theories and some observations suggest that the first large galaxies formed from the merger of smaller ones and the accumulation of hot gas in often violent processes.

Normally, it takes about 6 billion years for a galaxy to begin to have a well-formed disk like that of the Milky Way, four times the age of SPT0418-47, but recent discoveries indicate that galaxies can grow very fast by other ways, such as the accumulation of cold gas. In addition, both the new galaxy and the Wolfe Disc have the ability to form stars at a very high rate, something that indicates that, despite their stability, extremely energetic processes take place within them.

Although it now contains features similar to those of the Milky Way, billions of years from now, if you look in that direction again, the now-young SPT0418-47 will have become an elliptical galaxy, without spiral arms like the one our. In the coming years, the study of this object and other similar ones will help to adjust to reality the ideas that are had about the infancy of the universe and the formation of the first galaxies.

Source: elparis

All news articles on 2020-08-12

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