This function is an average of the amount of ultraviolet light associated with galaxies at any particular epoch. In their paper, Donnan's team calculate the "galaxy ultraviolet luminosity function" between redshifts of 8 and 15. Indeed, all the distant galaxy candidates display evidence for strong ultraviolet light emission, enough to possibly settle the debate as to what ionized the hydrogen gas in the universe, bringing an end to the so-called " Cosmic Dark Ages." Over the years, astronomers have suggested causes ranging from radiation from the first stars and galaxies to outflows of radiation from the first supermassive black holes. If a closer look at the archived data does reveal the galaxy, then Maisie's Galaxy must produce very strong ultraviolet light from a powerful burst of star formation for Hubble to have spotted it.
The astronomers found that this galaxy may have also been seen by the Hubble Space Telescope, but not recognized at that time. Meanwhile, using the same observations from CEERS, another team led by Steven Finkelstein of the University of Texas at Austin discovered a galaxy with a redshift of 14.3, placing it 280 million years after the Big Bang, which the researchers have named "Maisie's Galaxy" after Finkelstein's daughter. The team also found five other galaxies with a redshift greater than 12, all of which exceed the redshift record set by JWST's predecessor and now colleague, the Hubble Space Telescope. student Callum Donnan of the University of Edinburgh, found a candidate galaxy at a redshift of 16.7, which equates to just 250 million years after the Big Bang. JWST's Near-Infrared Spectrograph (NIRSpec) joins in observations of six of those patches, while the space telescope's Mid-Infrared Instrument (MIRI) studies four.
These images are part of the Cosmic Evolution Early Release Science (CEERS) survey, which consists of images of 10 different patches of sky by JWST's Near-Infrared Camera (NIRCam). Two other papers report finding high-redshift galaxies in patches of the sky where JWST has simply taken deep exposures, without resorting to gravitational lensing. Because of cosmic expansion, today these galaxies would be over 35 billion light-years away from us. If validated, these galaxies would be, by far, the most distant ever detected. Astronomers led by Haojing Yan of the University of Missouri-Columbia used the gravitational lens created by the galaxy cluster SMACS J0723 to detect 88 candidate galaxies beyond a redshift of 11, including a handful estimated to be at a redshift of 20.
The galaxies have been detected using different techniques.