Astrophysicists reveal the largest 3D map of the Universe ever made.

This map is the result of a collaboration of more than twenty years between hundreds of scientists, from thirty different institutions around the world.

The largest 3D map of the Universe ever produced is the result of more than twenty years of collaboration between hundreds of scientists. DISCLOSURE / AFP

Astrophysicists around the world released on Monday, July 20, the largest 3D map of the universe ever made, resulting from the analysis of more than four million galaxies and quasars (ultraluminous objects emitting colossal energy).

“This work simply provides us with the most complete history of the expanding universe to date”, said one of the researchers, Will Percival, from the University of Waterloo.

This map was drawn from collaborative work that brought together several hundred scientists, including French, gathered in the Sloan Digital Sky Survey (SDSS), and was based on an optical telescope located in New Mexico,United States.

Thanks to the numerous theoretical works carried out over time in the Big Bang, as well as the observation of the cosmic diffuse background (a weak radiation of light left by the Big Bang), the first moments of the Universe are relatively well known by researchers.

The map shows that, at some point, the expansion of the Universe accelerated. DISCLOSURE / AFP

Studies on galaxies and distance measurements have also given a good understanding of the expansion of the Universe that has occurred in the past billions of years.

“However, there was still a lack of data between the beginning of the Universe and the current period,” explains Kyle Dawson, of the University of Utah.

“In 2012, I launched the eBOSS project with the idea of ​​producing the most complete 3D mapping of the Universe, using for the first time new trackers, which are the galaxies that actively form stars and quasars”, details Jean-Paul Kneib, astrophysicist at Ecole Polytechnique Fédérale de Lausanne (EPFL).

Dark energy

O mapa mostra filamentos de matéria e vazios que definem a estrutura do Universo desde seus primeiros dias, quando tinha “apenas” 380.000 anos de idade.

The map shows filaments of matter and voids that define the structure of the Universe since its early days, when it was “only” 380,000 years old.

In the part of the map related to the Universe six billion years ago, researchers looked at the oldest and reddest galaxies. For more distant ages, they focused on the younger blue galaxies.

To go back,up to eleven billion years ago, they used quasars – galaxies whose supermassive black hole, at its center, is made extremely luminous by the matter that is swallowed.

The map confirms that, at some point, the expansion of the Universe accelerated and, since then, has continued to do so.
This acceleration seems to be due, according to the researchers, to the presence of dark energy, an invisible element that is part of Einstein’s general theory of relativity, but whose origin is not yet known.

This work simply gives us the most complete history of the expansion of the Universe so far ”, highlights one of the researchers of the eBOSS project. DISCLOSURE / AFP.

Comparing the observations made by the eBOSS program with the studies carried out until today in the early days of the Universe,
the researchers found a delay in estimates of the accelerating expansion of the Universe.

The value of the Hubble constant, which describes the expansion rate of the Universe at any given time, was found in the eBOSS measurements 10% lower than the deduction from the observation of the distance between nearby galaxies. These new measures confirm once again the heterogeneity of the Hubble constant value estimates, according to the methods used, a heterogeneity that until now remains unexplained.

  • By Le Monde with AFP /Published 20/07/2020