Astronomers use advanced tools to Calculate A more accurate age for the Macy’s galaxy, discovered by the James Webb Space Telescope (JWST) in June 2022. Although the star system is not quite as old as first estimated, it is still one of the oldest galaxies on record, from 390 million years after the Big Bang – It is about 13.4 billion years old. That’s just 70 million years younger than JADES-GS-z13-0the oldest known (current) system.
A team led by University of Texas at Austin astronomer Stephen Finkelstein Discover order last summer. (The name “Maisie’s Galaxy” is an ode to his daughter because they discovered it on her birthday.) The group initially estimated it to be only 290 million years after the Big Bang, but analysis of the galaxy with more advanced equipment revealed it to be about 100 million years older than that. “The exciting thing about Macy’s galaxy is that it was one of the first distant galaxies identified by JWST, and of this group, the first spectrally confirmed,” Finkelstein said.
Spectral confirmation came courtesy of JWST’s Near Infrared Spectrum (NIRSpec) conducted by the Cosmic Early Evolution Science Survey (CEERS). NIRSpec “breaks down an object’s light into many different narrow frequencies to more accurately determine chemical composition, heat output, intrinsic brightness and relative motion.” Redshift – the movement of light toward longer (red) wavelengths to indicate movement away from the observer – held the key to more accurate dating than the original photometric-based estimate. Advanced instruments gave a redshift of z = 11.4 for the Maisie galaxy, helping researchers settle on the revised estimate for 390 million years after the Big Bang.
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Astronomers also first examined CEERS-93316 estimated in 235 million years before the Big Bang – which would have made it startlingly old. After studying this system, it revealed a redshift of z = 4.9, which puts it only a billion years after the Big Bang. The first miscalculation about CEERS-93316 was understandable: the galaxy has emitted an unusual amount of light in narrow frequency bands associated with oxygen and hydrogen, making it appear bluer than it was.
Finkelstein counted the error to bad luck. “This was a rather strange case,” he said. “Of the dozens of high redshifts observed through spectroscopy, this is the only example of the true redshift being much lower than our initial guess.” Finkelstein added, “It was really difficult to explain how the universe could have created such a massive galaxy so soon. So, I think that was always the most likely outcome, because it was so intense, so bright, at such an obvious high redshift.”
The CEERS team is now evaluating about 10 other systems that could be older than the Macy’s galaxy.
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