“We’ve hit on something incredibly fascinating. These galaxies must have started to form only 100 million years after the Big Bang., testifies Garth Illingworth, professor at the University of California at Santa Cruz. This American astrophysicist is one of the researchers who worked on the first photos taken by the James-Webb Space Telescope (or JWST), in service since this summer. The machine specializes in infrared observations, a range of wavelengths essential for understanding the origins of the universe. And in particular its beginnings, just after the Big Bang which occurred 13.77 billion years ago.
Because the older a star or an astronomical object, the more the light it emits draws towards the red (due to the expansion of the universe). The very first galaxies that formed after the Big Bang are so red that they are no longer visible to the human eye – it takes an infrared telescope like James-Webb to see them. And the first results of the NASA jewel go beyond all expectations.
Archaeological dig
James-Webb began observing the cosmos in July. And from the first data received on Earth, the discoveries began to rain. “In just four days of analysis, researchers found two exceptionally bright galaxies in the JWST imagessays a statement from the US space agency. These galaxies existed around 450 and 350 million years after the Big Bang, which Webb’s future spectroscopic measurements will help confirm.”
There are several amazing and damn gratifying facts in there. First, James-Webb found the oldest known galaxies immediately after it was put into operation. This proves that it is very powerful, and that finding primitive galaxies will now be child’s play with this telescope. Records will no doubt continue to fall, and we will take a giant step forward in our understanding of the beginnings of the universe. “According to predictions, we thought we would have to search a much larger volume of space to find such galaxies” early, says Marco Castellano of the National Institute of Astrophysics in Rome. He is the main author of one of two studies just published on the subject in The Astrophysical Journal Letters. His colleague Paola Santini adds: “These sightings have blown our heads off. It’s a whole new chapter in astronomy that opens. It’s like an archaeological dig, where you suddenly find a lost city or something you didn’t expect. It’s amazing.”
dark ages
The other aspect that stunned astronomers is the light intensity of these dinosaur galaxies: they are much brighter than expected for such ancestors. Illingworth imagines two explanations. Either these galaxies were massive and filled with myriads of small stars, or they were lighter but with a few giant and extraordinarily bright stars. To know if we are indeed dealing with super-stars from primitive times, these hypotheticals “population stars IIIas theorized by astrophysicists, it will be necessary to precisely analyze the spectrum of light from these galaxies.
Our two red spots were therefore immortalized by James Webb as they were 350 and 450 million years after the Big Bang. This means that they had time to develop before, and that their birth is even older. This is why Garth Illingworth estimates the beginning of their formation at 100 million years after the Big Bang. “No one expected the Dark Ages to end so soon”explains the American. dark agesit is the period in the history of the universe which precedes the “ignition” of the first generation of stars. “The early universe was then only a hundredth of its current age. It’s a blink of an eye on the scale of this cosmos of 13.8 billion years.