James Webb detects the most distant galaxy ever observed

Another record for the James Webb Space Telescope (JWST) which discovered the most distant galaxy, therefore the oldest, which existed around 290 million years after the Big Bang, 13.8 billion years ago. The light of this new galaxy, named “JADES-GS-z14-0” (JADES to say JWST Advanced Deep Extragalactic Survey), took 13.5 billion years to reach the main mirror of JWST. According to NASA which made the announcement, it is “ exceptionally bright considering its distance “. In astronomy, seeing far means going back in time. How could a galaxy so young, so luminous despite its distance, and so massive, several hundred million times the mass of the Sun, have developed and in such a short time, at the cosmic dawn? It does not correspond to any of the astrophysical models generated by computer simulations. Astrophysicist Sylvie Vauclair, professor emeritus at the University of Toulouse, asks, “ Is this galaxy an exception? Is it the representative of an unsuspected class of primordial galaxies? Does its great luminosity correspond to a long-term evolution, or are we by chance observing a particular burst of light, a period of intense star formation for example? So many questions which can only be resolved by research into other similar galaxies, future statistical observations ».

A discovery that shakes up all current ideas on the formation of galaxies

Several hypotheses have already been put forward, the main one of which assumes a high density of the primitive Universe. In the meantime, this revolutionary discovery shakes up all current ideas on the formation of galaxies. “ During the evolution of scientific knowledgeenthuses Sylvie Vauclair, we sometimes find ourselves confronted with exceptional discoveries which lead to bifurcations in our knowledge. The discovery of the galaxy JADES-GS-z14-0 is at the same level of importance “. And that’s not all, another fundamental discovery, spectroscopic observations showed the presence of oxygen in JADES-GS-z14-0. How can we understand these traces of oxygen since the most widespread chemical elements in the Universe, hydrogen and helium, are also the lightest and simplest? It is only by merging inside stars, and after multiple generations of stars, that they end up producing more chemically complex elements including oxygen. Finding oxygen in this galaxy from the very beginning of the Universe is like “ discover a smartphone in the archaeological ruins of ancient Rome!», According to astrophysicist Kevin Hainline, associate professor at the University of Arizona in the United States. Indeed there was no oxygen in the matter of the early Universe, nor any other heavy element. “ This provesexplains Sylvie Vauclair, that stars much more massive than the Sun existed very early and evolved in record time, enough to manufacture the first heavy chemical elements in their nuclear core, and to release them into space before the formation of this galaxy, which has taken possession of it ».

The powerful space telescope continues to surprise us…

If for more than two years, astronomy has multiplied revolutionary discoveries, it is thanks to the images from space and the incredible data on the history of the stars that JWST, launched in December 2021, continues to collect. This observatory, built by the American (NASA), European (ESA) and Canadian (ASC) space agencies, is stationed 1.5 million kilometers from Earth in order to explore the very young Universe. To capture the light emitted by distant celestial objects, James Webb works in infrared, an electromagnetic radiation of wavelength invisible to the naked eye but which can pass through certain dusty areas of the sky. This engineering gem notably has a NIRCam camera which can detect stars or planetary systems in formation and a NIRSpec near-infrared spectrometer, built by European manufacturers, which makes it possible to obtain the spectrum of several objects at the same time. times. Thus the JADES-GS-z14-0 galaxy was detected in 2023 using the NIRCam imager. But it was a year later, thanks to the NIRSpec spectrometer, that its distance could be established. As Sylvie Vauclair notes, “ JWST, with its distant infrared observation capabilities, continues to surprise, amaze and question us! “. Indeed, JWST’s mission should last around twenty years.