Far out cosmology: webb view of early universe (Introduction)

by David Turell , Saturday, November 19, 2022, 18:02 (521 days ago) @ David Turell

The telescope is seeing the formation of early galaxies occurs at high speed:

https://phys.org/news/2022-11-webb-space-telescope-reveals-birth.html

"The earliest galaxies were cosmic fireballs converting gas into stars at breathtaking speeds across their full extent, reports a UCLA-led study to be published in a special issue of The Astrophysical Journal.

"The research, based on data from the James Webb Space Telescope, is the first study of the shape and structure of those galaxies. It shows that they were nothing like present-day galaxies in which star formation is confined to small regions, such as the constellation of Orion in our own Milky Way galaxy.

***

"'Webb's incredible resolution allows us to study these galaxies in unprecedented detail, and we see all of this star formation occurring within the regions of these galaxies."

***

"Webb is the largest near-infrared telescope in space, and its remarkable resolution offers an unparalleled view of objects so distant that their light takes billions of years to reach Earth. Although those objects have aged by now, light from only their earliest moments has had enough time to travel through the universe to end up on Webb's detectors. As a result, not only has the Webb functioned as a sort of time machine—taking scientists back to the period shortly after the Big Bang—but the images it's producing have become a family album, with snapshots of infant galaxies and stars.

***

"The project seeks to understand how and when light from the first galaxies burned through the hydrogen fog left over from the Big Bang—a phenomenon and time period called the Epoch of Reionization—and how gas and heavy elements are distributed within and around galaxies over cosmic time. Treu and Roberts-Borsani use three of the Webb's innovative near-infrared instruments to take detailed measurements of distant galaxies in the early universe.

"The Epoch of Reionization is a period that remains poorly understood by scientists. Until now, researchers have not had the extremely sensitive infrared instruments needed to observe galaxies that existed then. Prior to cosmic reionization, the early universe remained devoid of light because ultraviolet photons from early stars were absorbed by the hydrogen atoms that saturated space.

"Scientists think that sometime within the universe's first billion years radiation emitted by the first galaxies and possibly by the first black holes caused the hydrogen atoms to lose electrons, or ionize, preventing photons from "sticking" to them and clearing a pathway for the photons to travel across space. As galaxies began to ionize larger and larger bubbles, the universe became transparent and light traveled freely, as it does today, allowing us to view a brilliant canopy of stars and galaxies each night.

"Roberts-Borsani's finding that galaxies formed faster and earlier than previously thought could confirm that they were the culprits of cosmic reionization. The study also confirms the distances to two of the farthest galaxies known using a new technique that allows astronomers to probe the beginning of cosmic reionization.

Comment: this helps outline the evolution of the universe after the Big Bang, showing the 'how' but not the 'why' of the process.