NASA's James Webb Space Telescope discovers most distant galaxy ever observed

https://blogs.nasa.gov/webb/2024/05/30/nasas-james-webb-space-telescope-finds-most-distant-known-galaxy/

Astronomers have been using NASA's JWST infrared space telescope to study galaxies that are thought to have formed in the first few hundred million years after the Big Bang, which could provide important insights into how gas, stars, and black holes evolved in the early universe.

In the first year of observations, the JWST Advanced Deep Extragalactic Survey (JADES), one of the space observation programs using JWST, discovered hundreds of galaxies that are thought to have arisen 650 million years after the Big Bang. In addition, in early 2023, galaxies with redshifts of 14 or more were discovered. The discovered galaxies were so bright that it was hard to believe they were observed so far away. In addition, the observed galaxy was very close to another galaxy, so it was thought that the two were part of a single large celestial object.

As part of JADES, an international team of astronomers will use the JWST to observe galaxies from October 2023 to January 2024. Using the JWST's NIRSpec (near-infrared spectrometer), the team has been able to capture the spectrum of a galaxy born just 290 million years after the Big Bang.

In October 2023, the research team used JWST's NIRSpec to capture images suggesting the high redshift hypothesis. In addition, in January 2024, they successfully observed a galaxy called 'JADES-GS-z14-0' for nearly 10 hours using NIRSpec. After processing the galaxy's spectrum, it was found that the redshift of 'JADES-GS-z14-0' was '14.32'. Since the redshift of 'JADES-GS-z13-0', the most distant galaxy detected so far, was '13.2', 'JADES-GS-z14-0' is proven to be the most distant galaxy observed so far.

Below is 'JADES-GS-z14-0' photographed by JWST's NIRSpec. The redshift is '14.32 (+0.08 / -0.20)', and 'JADES-GS-z14-0' is estimated to be a galaxy that occurred 290 million years after the Big Bang.

In addition, it was proven that 'JADES-GS-z14-0' is 1600 light years in size, and that most of the radiation is from young stars, not from the vicinity of a growing supermassive black hole. This amount of starlight means that this galaxy has a mass hundreds of millions of times that of the Sun. Therefore, the research team writes, 'How could nature have succeeded in creating such a bright, massive, and large galaxy in less than 300 million years?'

In addition, it was revealed that the color of 'JADES-GS-z14-0' is not blue. Even in the very early stages, some of the light seems to be reddened by dust. Jake Helton, a researcher at Steward Observatory and the University of Arizona and a member of JADES, noted that 'JADES-GS-z14-0' was also detected at longer wavelengths using JWST's MIRI (mid-infrared instrument).

MIRI's observations cover wavelengths of light emitted in the redshifted visible range that JWST's NIRSpec cannot reach. According to Helton's analysis, the brightness of the source observed by MIRI exceeds that estimated from other JWST measurements, indicating the presence of strong ionized gas emission in the galaxy in the form of bright emission lines of hydrogen and oxygen. The presence of oxygen in the early stages of the galaxy's formation was surprising, and 'suggests that multiple generations of very massive stars had already completed their lives before the galaxy was observed,' the team wrote.

The graph below shows the brightness on the vertical axis and the wavelength of light on the horizontal axis. Redshift is measured using a method called the Lyman Break method, which uses the effect of hydrogen gas between galaxies scattering and absorbing light from celestial objects.

JADES-GS-z14-0 is not the type of galaxy predicted to exist in the early universe by theoretical models and computer simulations. So far, no suitable analogues have been found among the hundreds of other galaxies observed at high redshifts in the survey. However, because the area of sky searched to find JADES-GS-z14-0 was relatively small, the predicted number of bright galaxies seen in the early universe may change significantly in the future, as discussed in another study.