James Webb finds unexpectedly many dying galaxies in the early universe

The early universe was expected to contain only young and active galaxies, but new observations have disproved this. The James Webb Infrared Space Observatory has discovered an unexpectedly large number of dying galaxies in the first billion years after the Big Bang, where new stars have stopped being born. The difference between theory and observation has shocked scientists, forcing them to rethink their understanding of the evolution of the universe.

Image source: AI generation Grok 3/3DNews

The task of searching for dying or sleeping galaxies (quiescent galaxies), in particular, was undertaken by scientists within the framework of the European large-scale program RUBIES (Red Unknowns: Bright Infrared Extragalactic Survey), which relied on data from the NIRSpec instrument of the James Webb telescope. The program made it possible to collect spectroscopic observations of several thousand galaxies, including hundreds of objects recently discovered by Webb.

Spectrum analysis showed that in the first billion years after the Big Bang, the actual number of dying galaxies was 100 times greater than theoretical predictions, and this is a reason to think about the validity of existing theories about the evolution of stars, galaxies, and the Universe. Apparently, terrestrial science incorrectly estimates the influence of stellar wind and black hole activity on the processes of star formation in the first galaxies. All this can stop the birth of new stars much earlier and lead galaxies to extinction.

In the Webb data, the University of Geneva (UNIGE) team, who lead the RUBIES program, discovered a record-holder – the oldest extinct galaxy. This is the object RUBIES-UDS-QG-z7, which looks dead already 700 million years after the Big Bang (redshift 7.29). Modeling based on the Webb data showed that the galaxy formed a stellar mass of over 10 billion solar masses during the first 600 million years after the Big Bang and then quickly stopped star formation.

The spectrum of a distant, extinct galaxy is at the center of the image. Image credit: NASA

The discovery suggests another important conclusion. The galaxy RUBIES-UDS-QG-z7 is small in size — only about 650 light years — but retains a high stellar mass density comparable to the central regions of modern galaxies. Scientists suggest that galaxies that died out in the early Universe could have become the nuclei of massive galaxies in subsequent eras, including our own. This is another reason to reconsider our understanding of the true evolution of the Universe, which Earth science seems to have not understood quite correctly until now.