2023-06-05 12:15:42
After the Big Bang, which is the “explosion” with which the universe was born approximately 13.8 billion years ago, the cosmos expanded and cooled enough for hydrogen atoms to form. Until the birth of the first stars and the first galaxies (large collections of stars and other bodies), the universe was essentially in the dark. That period is called the cosmic dark era. The appearance of the first stars and galaxies, a few hundred million years later, bathed the universe in energetic ultraviolet light that began to “burn,” or ionize, the hydrogen mist. This, in turn, allowed other photons to travel through space, making the universe transparent and light propagating through it.
Knowing what those first galaxies that made that epoch, called the Reionization Epoch, were like is an important goal of today’s astronomy, but until the entry into service of the Webb Space Telescope, there was no instrument that was sensitive enough in the band infrared enough to study the first generation of galaxies.
The international team led by Guido Roberts-Borsani, from the University of California in Los Angeles, United States, has confirmed the existence of one of those archaic galaxies.
The finding will help to better understand how the dark age of the universe ended.
That galaxy, called JD1, is one of the most distant identified to date, and its characteristics match those expected of galaxies that sent their light through the fog of hydrogen atoms left over from the Big Bang, making it possible Let the light shine through the universe.
JD1 is so faint and so far away that it is difficult to study without a powerful telescope and the help of nature… JD1 lies behind a large cluster of nearby galaxies, called Abell 2744, whose combined gravitational force bends and amplifies light from JD1, making it appear larger and 13 times brighter than it would otherwise. The effect, known as gravitational lensing, is similar to the way a magnifying glass distorts and amplifies light within its field of view. Without the gravitational lens, JD1 would probably have gone undetected.
The galaxy JD1 (inset) and its location in the sky, behind the galaxy cluster Abell 2744. (Image: Guido Roberts-Borsani / UCLA; Original photos: NASA, ESA, CSA, Swinburne University of Technology, University of Pittsburgh, STSCI)
Since light takes as many years to reach Earth as light-years separate us from the source of that light, we see each astronomical object not as it is now but as it was when it emitted the light we now receive. In the case of JD1, we now see this galaxy as it was approximately 13.3 billion years ago, when the universe was only 4% of its current age.
The study is titled “The nature of an ultra-faint galaxy in the cosmic dark ages seen with JWST”. And it has been published in the academic journal Nature. (Fountain: NCYT de Amazings)
#Galaxy #universe #lit #stars