Astronomers have used the James Webb Space Telescope (JWST) to find three of the earliest galaxies ever found.
They exist less than 400 million years after the Big Bang—a whopping 13.4 billion years ago—when the universe was only 2% of its current age.
The galaxies were found in the same path of the night sky—close to the Big Dipper—where the iconic Hubble Ultra Deep Field image was taken.
When JWST began operations last summer several extreme candidates for “most distant galaxy ever found” emerged almost immediately. Now scientists on the JWST Advanced Deep Extragalactic Survey (JADES) Initial have conducted lengthy observations to confirm four of them by measuring their distances and physical properties.
“We’ve discovered galaxies at fantastically early times in the distant universe,” said Brant Robertson, professor of astronomy and astrophysics at UC Santa Cruz. “With JWST, for the first time we can now find such distant galaxies and then confirm spectroscopically that they really are that far away.”
“We are seeing evidence of star formation about as early as we could expect based on our models of galaxy formation,” he said.
Spectroscopy is when astronomers split the light they collect into different wavelengths, creating a rainbow-like spectrum. JWST is fitted with a Near Infrared Camera (NIRCam), which was used to collect the ancient stretched red light from these prototype galaxies in nine different infrared wavelength ranges.
Old light in the universe is red because the universe is expanding. Red light has the longest wavelength. The so-called “redshift” measured by JWST’s NIRCam for four galaxies was 10.38, 11.58, 13.20 and 12.63, making three of them the most distant galaxies confirmed by spectroscopy to date.
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“These are well beyond what we could have imagined finding before JWST,” said Robertson. “At redshift 13, the universe is only about 325 million years old.
Reference: Forbes
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