Science

Lofar radio telescope reveals thousands of star nursery galaxies

The European LOFAR radio telescope on Wednesday revealed, via a series of studies, images of unprecedented precision of tens of thousands of galaxies forming stars in the “young” Universe.

This is the second delivery of data from this network of some 70,000 antennas spread over ten European countries. They observe particles moving at a speed close to light, accelerated by events such as the explosion of stars, collisions of galaxy clusters or the activity of black holes.

To distances, and therefore to ages, when the Universe was still young. With a signal emitted by the most distant detected objects, when the Universe was only a billion years old. It is now about 13.8 billion years old.

“The scientific heart of the project is the study of the formation of galaxies and the functioning of black holes in their centers”, explains to AFP the astronomer Cyril Tasse, of the Observatory of Paris-PSL.

The astronomer is one of the authors of the 14 studies devoted to this unpublished LOFAR dataset, collected in a special issue of the journal Astronomy and Astrophysics, published Wednesday.

The telescope focused on a wide field of the northern sky, with the equivalent of an exposure time ten times longer than that which allowed the delivery of its first cosmic map, in 2019.

“This gives much finer results, such as a photo taken in the dark, where the longer you pose, the more you can distinguish things” that are difficult to see, specifies Cyril Tasse.

Image of galaxies detected by radio, in orange on the left, in the center at the bottom and on the right, associated with a view of the sky seen by an optical telescope, broadcast by the Paris Observatory on April 6, 2021 (OBSERVATOIRE DE PARIS – PSL / AFP – Handout)

Around 3 billion years after the Big Bang, “it really is fireworks,” with a “peak in star formation and black hole activity” in young galaxies, he adds.

LOFAR observes it indirectly, by detecting cosmic radiation – the energy released by the galaxy – which is accelerated by supernovas, those stars that explode when they die.

“When a galaxy forms stars, lots of stars explode at the same time, which accelerates the particles at very high energy, and the galaxies begin to radiate” in this range of radio waves observed by LOFAR, explains the astronomer .

These data, coupled with those collected by other means of observing the sky – optical or in the ranges of X or infrared radiation – should make it possible to better understand the evolution of the Universe. While waiting for the launch of new radio means to bring this observation back to the early youth of the Universe.

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