The Noema radio telescope in the Hautes-Alpes, the most powerful in the northern hemisphere, is getting new antennas

It is an extraordinary place. We still need a few minutes of hiking and we arrive at the top of the Bure plateau. We are at an altitude of more than 2,000 m and that’s it, we can see these huge parabolas pointing towards the sky. “You see the antennas which are observing, they point strictly to the same position in the sky”explains Frédéric Gutt, Deputy Director of the Institute of Millimetric Radio Astronomy (Iram).

These strange parabolic antennas installed make it possible to detect radio waves from the universe, emitted by the stars. The same waves that allow you to listen to the radio. “They observe the same sourcesays Frédéric Gutt. Sources in the sky emit light or waves. So we know the optical wavelengths. This is what our eye sees. But we have all heard of infrared, ultraviolet and then radio waves. We can study the processes of star formation, the dynamics of galaxies.”

This installation in the Hautes-Alpes is called Noema, for Northern extended millimeter array. Eight years after the installation of its first antenna, the twelfth and last dish has just been commissioned. This makes Noema the most powerful radio telescope in the northern hemisphere and the second most powerful radio telescope in the world after Alma in Chile and its 66 antennas. It is the result of a scientific project involving France, Germany and Spain. It is to be inaugurated on September 30 by the Minister of Research Sylvie Retailleau and her German counterpart.

On this plateau, there are obviously these twelve antennas, but also a living base where the people who operate this radio telescope work and live and then a huge hangar. “This is the hall in which the antennas were builtexplains the deputy director of Iram. All the elements of the antennas are mounted on the Bure plateau and then the teams assembled everything to build this antenna of 120 tons and 15 m in diameter.

These parabolas move on rails. In recent months, the tracks have been extended to 1.7 km, which allows you to zoom in a little more. “We are here in the control roomdescribes André, one of the telescope operators. We are going to adjust the receivers, the antennas and so we left for a five-hour observation on a group of eight galaxies which are very far in the Universe, between 10 and 11 billion light years.

On these screens, a multitude of figures, graphs, these are the radio signals that astronomers like Edvige will then decipher. “We will translate the different frequencies into visible colors so that we can see themexplains the astronomer. But they will indeed be false color images. In millimeters, we are sensitive to anything that is very cold, less than 170° Celsius, and we will see dust. And we will also be sensitive to the gas and mainly to the molecular composition of this gas.” And among the feats of arms of the Noema telescope, we find the observation of the most distant galaxy known to date.