There are certain key questions that go hand in hand with mapping the changing nature of Dark Energy.
For instance, we’re looking to the early universe to see when the first galaxies came to light and how fast they and other structures grew into systems we might see in our modern universe. And while DESI, Euclid, and SphereX are out there mapping how structures evolved, it’s JWST that is showing us how they formed.
Prior to JWST’s annoyingly early Christmas Day launch – for which I remain bitter – we had thought galaxies started to light up around a billion years after the universe formed, give or take a few hundred million years. We thought it would take time for small galaxies to grow into large galaxies and for the opaque neutral gas that fogged up outer space to be cleared away by galaxies’ ultraviolet light.
We thought wrong.
JWST has been finding early galaxy after early galaxy and consistently pushing backwards the time of first galaxy formation. One of these galaxies, JADES-GS-z13-1, was first identified in 2022 and appeared to be shining from when the universe was roughly 350 million years old. It also appeared to be in a fairly foggy, gas-free region. Neither the existence of a large galaxy nor a fog-free region made a lot of sense, so new data was taken with JWST’s Near-IR spectrograph. The results appear in a new paper in Nature and confirm that this galaxy is shining from when the universe was just 330 million years old.
According to UK researcher Roberto Maiolino, “The early Universe was bathed in a thick fog of neutral hydrogen. Most of this haze was lifted in a process called reionization, which was completed about one billion years after the Big Bang. GS-z13-1 is seen when the Universe was only 330 million years old, yet it shows a surprisingly clear, telltale signature of Lyman-α emission that can only be seen once the surrounding fog has fully lifted. This result was totally unexpected by theories of early galaxy formation and has caught astronomers by surprise.”
Lyman alpha light comes from hydrogen gas, and is from the 2 to 1 energy transition. This ultraviolet light is associated with star formation and high-temperature environments. While it’s entirely possible this is a weird system that is doing something special in the early universe, it is astounding that we found this baby galaxy so quickly after JWST started to do science.