It is the most active place in the universe. It is located about 12400 million light-years from Earth and in it, new stars are formed 10,000 times faster than in the Milky Way. Their discovery has baffled astronomers since no theory or computer simulation predicted that such a colossal and massive cluster of galaxies could be formed as they have discovered only 1400 million years after the Big Bang when the universe had barely one-tenth of his age.
“Clearly we have found the most active corner of the universe,” explains Big Vang Scott Chapman, professor of astrophysics at the University of Dalhousie, Halifax (Canada), and specialist in cosmology. “We have discovered that it is composed of 14 massive galaxies in a compressed area, four times the diameter of the galactic disk that of the Milky Way, fusing with each other”, adds this researcher, co-author of the work published by Nature.
This agglomeration of young galaxies, which they have called SPT2349-56, is gravitationally bound by dark matter and swimming in an ocean of ionized hyper-hot gas. The galaxies are destined to end up merging with each other and end up forming the nucleus of what in the future will be a colossal galactic group and one of the most massive structures of the cosmos.
In fact, according to the calculations of astronomers, at present, this megacumulus, which has not stopped growing since it was formed, would have a mass equivalent to one billion trillion suns.
“It is surprising how extremely fast this cluster of galaxies has formed,” says Chapman. And it is a challenge to our current understanding of how these structures are formed in the universe. ” You have to think that these galactic groups are generated over the course of billions of years from materials that come from very distant points and that are gradually being assembled. “We did not expect at all that a cluster like this we discovered could have been formed in less than 1500 years,” he adds.
The megacumulus would currently have a mass equivalent to one billion trillion soles.
The galaxy clusters are the largest structures that exist in the universe. They began to form during the first stage of the history of the cosmos when normal matter and dark matter began to unite and form ever-increasing concentrations held together by gravity. They contain thousands of galaxies and have masses comparable to a billion solar masses, in addition to growing as their gravity attracts more and more material.
In this sense, until now astronomers thought that this type of massive objects could only begin to occur 3000 years after the Big Bang. That’s why astronomers believe that this discovery is a formidable opportunity to study how these structures are formed and how they merge.
This mega-cluster of galaxies spews thousands of stars each year, compared to the formation of a single star in the Milky Way at the same time. Due to this frenetic activity, these galaxies probably have a very short life, because they consume the gas they contain at a very high speed.
The most powerful instruments
This cluster of galaxies was first observed in 2010 with the South Pole Telescope. And then it appeared like a faint blur of light. Later observations with the APEX experiment (Atacama Pathfinder Experiment) and the ALMA interferometer (Atacama Large Millimeter / submillimeter Array), the two most powerful astronomical instruments in the world, allowed an international team of astronomers, led by Chapman, to distinguish the 14 galaxies.
“We were trying to find out what were the weak spots of light that we had captured with the South Pole Telescope. We thought that maybe they could be individual galaxies and even with a bit of luck a huge proto-cumulus of galaxies. To our surprise when we looked at ALMA in detail we saw that it was the tip of the iceberg of huge structures formed very early in the history of the universe. We could not believe how massive and active the system was, “confesses Chapman.
Using the data collected by ALMA, they performed a computer simulation to see what the evolution of this mega-cell would be like in the next billion years and saw the 14 galaxies merge into a single, a giant elliptical galaxy that will be surrounded by a halo of galaxies, stars, and stardust.
“[This megagalaxy] would exceed everything we’ve seen in the local universe,” says Carlos de Breuck, an astronomer at the European Space Observatory (ESO) in a press release.
The discovery allows us to better understand how the largest structures in the universe we see today were formed and sheds light on some inconsistencies in the simulations that astronomers used to understand the formation of galaxies. The next step, explains Chapman, is to “expand the survey to try to find more structures of this type and understand whether or not it is a common phenomenon in the formation of clusters.”