An article published in the journal “Nature” describes the discovery of four galaxies that are very ancient, so much that they formed less than a billion years after the Big Bang. A very high stellar formation rate was observed within them. A team of astronomers led by Roberto Decarli of the Max Planck Institute for Astronomy discovered by chance these four galaxies, noting that they were close to as many quasars.

Roberto Decarli’s team’s research was aimed at studying galaxies that host quasars, extremely galactic nuclei that are extremely bright due to supermassive black holes surrounded by rings of materials falling towards them, generating very high levels of electromagnetic radiation. For this study they used the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope, which allowed to observe 25 quasars during a single research program. That’s because ALMA, inaugurated in March 2013, allowed a single observation in just 10 minutes still achieving a very high quality.

The surprise came when in 4 of 25 cases the astronomers also observed galaxies near them that were very ancient and had a very high star formation rate. The really interesting combination of characteristics is that they are galaxies over 12 billion light years away, which means that the electromagnetic emissions captured by Earth’s instruments were emitted when the universe was less than a billion years old.

Probably it’s not coincidence that a high star formation galaxy was close to one with a quasar because in both cases this suggests a material density much higher than the average. In those galaxies, star formation was estimated in one hundred solar masses per year, while in the Milky Way the rate is one solar mass per year.

The astronomers were surprised by this discovery but this is not something totally new because a few years ago extremely massive and very ancient galaxies were observed. For example, an article published in the magazine “Astrophysical Journal” in November 2015 describes a research on this topic.

This new discovery could provide an explanation for the existence of these ancient giant galaxies. A hypothesis that was offered studying the first galaxies of that type discovered was that they had precursors, which could be galaxies just like the newly discovered ones.

The team led by Roberto Decarli also discovered the oldest case of galactic merger observed. That’s a mechanism of galaxy growth and proves that it also happened when the universe was very young. In essence, the first giant galaxies may have formed relatively soon after the Big Bang.

Instruments such as the ALMA radio telescope are allowing to investigate with increased details very distant galaxies and therefore areas of the almost primordial universe. This type of research is providing valuable information but there’s still a lot to be understood and that’s why Roberto Decarli’s team will keep on studying those galaxies.