The James Webb Space Telescope (JWST) has revisited a classic image of the Ultra Deep Field, taken by the Hubble Space Telescope in 2004. The new image reveals over 2,500 galaxies, many of which existed during the first billion years of cosmic history.
The JWST Advanced Deep Extragalactic Survey (JADES) project aims to probe infrared light into two patches of sky originally imaged by Hubble: the Hubble Deep Field and the Hubble Ultra Deep Field. The deep fields were Hubble’s most intense stares into the universe, revealing faint galaxies at high redshifts.
The JWST has surpassed Hubble’s limitation in observing distant galaxies, which are visible only in infrared wavelengths beyond its capacity. The telescope’s Mid-Infrared Instrument (MIRI) captured the latest image, using a 41-hour exposure of its shortest-wavelength filter.
The new image shows four-fifths of the visible galaxies as truly distant, high-redshift galaxies. However, none are record-breakers, with maximum redshifts of around 12. The current highest redshift galaxy is MoM-z14, which has a redshift of 14.4 and exists about 280 million years after the Big Bang.
The image provides insights into galaxies in various stages of evolution, from star-forming galaxies shrouded by dust to highly evolved galaxies with many older stars. The small greenish-white galaxies are those that exist mostly during the first billion years of cosmic history.
Source: https://www.space.com/astronomy/james-webb-space-telescope/james-webb-space-telescope-revisits-a-classic-hubble-image-of-over-2-500-galaxies