The galactic trio – the cosmic dawn of the Universe

A group of researchers led by a professor at the University of Tokyo has discovered a group of primitive galaxies 13 billion light years away, surrounded by a shell of hot ionized gas. Himiko, photographed when the universe was 800 million years old, has an interesting feature: the complete absence of carbon, the basic element of star formation, and an abundance of light elements.



They are a group of primitive galaxies 13 billion light years away, surrounded by a shell of hot ionized gas. And the group of galaxies was discovered by a team of astronomers using the Atacama Large Millimeter / submillimeter Array (ALMA) and the Hubble Space Telescope. We know that the Hubble Space Telescope represents the direct solution to a problem that telescopes have faced since the very earliest days of their invention: the atmosphere. Hubble is one of NASA’s most successful and long-lasting science missions. Hubble’s discoveries have transformed the way scientists look at the universe.

It is a triple system extremely rare and it was photographed at the moment when the Universe was “only” 800 million years. Precisely for this reason provides important new information about what is commonly called the cosmic dawn, so the first phase of galaxy formation.

The trio, dubbed with the name of Himiko (in honor of a legendary queen of Japan almost two thousand years ago) was spotted for the first time in 2009 and it looked like a giant bubble of ionized gas at extremely high temperatures. Next step was for the researchers to investigate more thrust using the Spitzer Space Telescope and discovered that it could be a single large galaxy. The strange thing that astronomers observed, was her size that of 10 times larger than were the galaxies in that period and comparable in size to our own Milky Way.



Only recently, experts have realized that it is, instead, a trio of galaxies, whose star heats the surrounding gas. These areas should be rich in heavy elements such as carbon, silicon and oxygen, which feed the combustion of young and ravenous stars. “The observations with ALMA, however, show the complete absence of carbon,” said Masami Ouchi, an associate professor at the University of Tokyo, whose research will be published in The Astrophysical Journal. “And this is one of the many mysteries of Himiko.” For this reason, experts speculate that much of the gas present prate about Himiko that could be a mixture of primordial light elements such as hydrogen and helium, which were created during the Big Bang. One of the most important results of the study, therefore, is precisely the discovery of the absence of many heavy elements in this galaxy.

Richard Ellis, professor at the California Institute of Technology and a member of the research team, said the discovery is “even more interesting because these galaxies seem to merge into a single massive far galaxy, which could eventually evolve into a galaxy similar to ours, the Milky Way.”

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