An article published in the journal “Astrophysical Journal” describes the discovery of the oldest giant galaxies carried out thanks to ESO’s VISTA (Visible and Infrared Survey Telescope for Astronomy) telescope. A team of astronomers led by Karina Caputi of the Kapteyn Astronomical Institute at the University of Groningen, Netherlands, identified galaxies that existed when the universe was between 750 million and 2.1 billion years old. This result is surprising because the birth of galaxies so massive wasn’t expected so soon.

The astronomers used images from the UltraVISTA survey, one of the projects that from December 2009 and for five years used the VISTA telescope to examine the sky in the near infrared. These data were combined with others collected by NASA’s Spitzer Space Telescope, which has been examining space in the mid-infrared. This type of observations allows to identify objects that are obscured by dust and are very distant.

The result was the discovery of 574 massive galaxies with masses of more than 50 billion that of the Sun which make up about half the number present when the universe was between 1.1 and 1.5 billion years old. This contradicts the current models of galaxy formation, which predicts the initial formation of small galaxies and only later of big ones, through galaxy mergers.

According to the analysis carried out on the data collected, these massive galaxies formed about a billion years after the Big Bang. Not only they have formed earlier than expected but they’re also more numerous than scientists thought. The telescopes available today and combining data from multiple telescopes allow to discover objects that were once invisible. This leads to surprises and consequently to new and better cosmological models.

A problem emerged during this research is that these massive galaxies seem to contain a lot of dust. The consequence is that there were probably others that emitted a light so dim that even the observations from the UltraVISTA survey couldn’t detect them.

This research opens the way for new studies to collect new data on early galaxies and adapt the models of their formation. ESO has already announced that the ALMA radio telescope will be used to search other galaxies full of dust. If they are found, they can become targets for the telescope E-ELT, whose construction begun in 2014.

[ad name=”AmazonDocumentary”]