- 4043 - EARLIEST GALAXIES - Webbs latest discoveries? James Webb Space Telescope finds the faintest galaxy ever detected at the dawn of the universe. These are the faintest galaxy ever seen, burning away the pitch-black gloom of the early universe 13 billion years ago. This ancient, nearly invisible star cluster is so remote that its light is the faintest scientists have ever detected.
----- 4043 - EARLIEST GALAXIES - Webbs latest discoveries?
- Called “JD1”, the
galaxy, whose light traveled for roughly 13.3 billion years to reach us, was
born just a few million years after the Big Bang. Back then, the cosmos was shrouded in a
pitch-black fog that not even light could pass through; galaxies like this one
were vital in burning the gloom away.
-
- Twinkling from
within the Sculptor constellation in the southern sky, JD1's light left its
source when the universe was just 4% of its current age. The light crossed
dissipating gas clouds and boundless space before passing through the galaxy
cluster Abell 2744, whose space-time-warping gravitational pull acted as a
giant magnifying lens to steer the ancient galaxy into focus for the JWST.
-
- In the first
hundreds of millions of years after the Big Bang, the expanding universe cooled
enough to allow protons to bind with electrons, creating a vast shroud of
light-blocking hydrogen gas that blanketed the cosmos in darkness. From the
eddies of this cosmic sea-foam, the first stars and galaxies clotted, beaming
out ultraviolet light that reionized the hydrogen fog, breaking it down into
protons and electrons to render the universe transparent again.
-
- Astronomers have
observed evidence for reionization in many places: the dimming of brightly
flaring quasars (ultrabright objects powered by supermassive black holes); the
scattering of light from electrons in the cosmic microwave background; and the
infrequent, dim light given off by hydrogen clouds. Because the first galaxies
used so much of their light to dissipate the stifling hydrogen mist, what they
actually looked like has long remained a mystery to astronomers.
-
- Most of the
galaxies found with JWST so far are bright galaxies that are rare and not
thought to be particularly representative of the young galaxies that populated
the early universe. While important,
they are not thought to be the main agents that burned through all of that
hydrogen fog.
-
- Ultra-faint
galaxies such as JD1 are far more numerous, which is why atronomers believe
they are more representative of the galaxies that conducted the reionization
process, allowing ultraviolet light to travel unimpeded through space and time.
-
- To discover JD1's
first stirrings from beneath its hydrogen, the researchers used the JWST to
study the galaxy's gravitationally lensed image in the infrared and
near-infrared spectra of light. This enabled them to detect JD1's age, distance
from Earth and elemental composition, as well as estimate how many stars it had
formed.
-
- The astronomers'
next task is to use their technique to unveil even more of these first
galaxies, revealing how they worked in unison to bathe the universe in light.
-
June 8, 2023 EARLIEST GALAXIES
- Webbs latest discoveries? 4043
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