File:NASA’s Webb Reaches New Milestone in Quest for Distant Galaxies (Just NIRCam) (52553294668).png

Preliminary Webb science shows galaxies confirmed by spectroscopy to date back to less than 400 million years after the big bang. Spectroscopy refers to breaking light into its components to create spectra, which can be thought of as “barcodes.” On a "barcode," elements and molecules have characteristic signatures we can read.

Because the universe is expanding, the light from distant galaxies is stretched — or redshifted — into longer, infrared wavelengths. We can figure out galaxies’ distances by measuring how much the signatures of elements in their spectra have shifted due to this effect.

Without spectroscopy, it can be hard to confirm how far away a galaxy is, as closer galaxies can “masquerade” as distant ones. To search for the earliest galaxies, scientists looked for a distinct feature in spectra that required Webb’s unprecedented infrared sensitivity to observe.

Finding and confirming early galaxies is a continuous process, and Webb is just getting started. Many more distant galaxies are lined up for Webb to investigate. Read more: <a href="https://blogs.nasa.gov/webb/2022/12/09/nasas-webb-reaches-new-milestone-in-quest-for-distant-galaxies/" rel="noreferrer nofollow">blogs.nasa.gov/webb/2022/12/09/nasas-webb-reaches-new-mil...</a>

Note: Data is from Webb science in progress, which has not yet been peer reviewed.

In this image: his image taken by the James Webb Space Telescope highlights the region of study by the Webb Advanced Deep Extragalactic Survey (JADES). This area is in and around the Hubble Space Telescope’s Ultra Deep Field. Scientists used Webb’s NIRCam instrument to observe the field in nine different infrared wavelength ranges. From these images, the team searched for faint galaxies that are visible in the infrared but whose spectra abruptly cut off at a critical wavelength. They conducted additional observations (not shown here) with Webb’s NIRSpec instrument to measure each galaxy’s redshift and reveal the properties of the gas and stars in these galaxies. In this image blue represents light at 1.15 microns (115W), green is 2.0 microns (200W), and red is 4.44 microns (444W). Image Credit: NASA, ESA, CSA, and M. Zamani (ESA/Webb).

Credits: NASA, ESA, CSA, M. Zamani (ESA/Webb). Brant Robertson (UC Santa Cruz), S. Tacchella (Cambridge), E. Curtis-Lake (UOH), S. Carniani (Scuola Normale Superiore), JADES Collaboration