 |
| This is what the newly discovered galactic monster might look like. | James Josephides / Christina Williams / Ivo Labbe |
The light radiation discovered by scientists would be a glow emanating from the particles of gas and dust heated by the stars that form in the hidden galaxy . However, this dust blocks other wavelengths, including that of stars.
In a sense, the newly discovered galaxy is therefore, for most of its elements, invisible. " It's debatable whether it's just the tip of the iceberg, with a whole new kind of galaxy population just waiting to be discovered, " said Kate Whitaker, co-author of the research.
The observations suggest that this galaxy is about 12.5 billion light years away , which means that the observed light was emitted 12.5 billion years ago. At that time, the Universe was in its infancy: it was barely a billion years old. This galaxy could therefore give clues to the rapid formation of gigantic mature galaxies at the beginning of the Universe.
Christina Williams, a postdoctoral researcher at the University of Arizona and lead author of the article, was the first to discover the galaxy. " It was very mysterious. The light did not seem to be related to a known galaxy. When I saw that this galaxy was invisible at any other wavelength, I was very excited because it meant it was probably far away and hidden by clouds of dust, "Williams said.
The video below shows what the new galaxy might look like (artist's view) in the primitive universe, with newly formed bursts of stars illuminating the clouds of gas and dust surrounding it:
This discovery could help solve a true mystery about galaxies : indeed, the new galaxy seems to contain about the same number of stars as our own galaxy, but it is much more active: it produces new stars at a speed 100 times faster than the Milky Way.
Right now, we know that large, mature galaxies appeared early in the Universe's history, whereas it was about a billion years old (or, as astrophysicists say, about 10% of its current age). But these galaxies seemed to come out of nowhere, growing and converting the gas into stars much faster than predicted the best theoretical models, before settling down again.
However, scientists have never observed this process directly. Indeed, NASA's Hubble Space Telescope has now spotted smaller galaxies at the beginning of the Universe, but none are growing fast enough to become as big ... However, a large active galaxy producing stars as well quickly could help astronomers determine what is missing from their models: " This hidden galaxy has precisely the right ingredients to be that missing link ," Williams said.
The researchers hope that future telescopes will be able to reveal more details about this galaxy or other objects of the same kind. At present, it is difficult to observe the galaxy or to find others with current telescopes, because it is invisible and the brightness of the surrounding dust clouds is very (too) weak. " We are excited that the James Webb Space Telescope (JWST) is examining these objects, " Williams said.
 |
| The James Webb Space Telescope, consisting of 18 hexagonal mirrors, is standing in the gigantic clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Credits: NASA / Chris Gunn |
Once in space, the JWST telescope will study each phase of the universe's history to understand how the first stars and galaxies were formed, how the planets were born and where there might be life. In the universe. Rather cheerful as a program.
A folding beryllium mirror, 6.4 meters wide, will help the telescope to observe distant galaxies in detail and capture extremely weak signals. " The JWST will be able to look through the dust veil so that we can understand how big these galaxies are and how fast they grow, in order to better understand why our current models fail to explain them, " he said. said Williams.
Source
Tags:
Space & Astrophysics