February 27, 2023
The James Webb Space Telescope (JWST) has uncovered something truly remarkable in the cosmos. It has captured its first glimpse of the distant universe and revealed galaxies that appear too big to exist. Astronomer Ivo Labbé and his team reported in Nature that six galaxies, formed within the first 700 million years of the universe, appear to be up to 100 times more massive than current cosmological theories predict. In fact, the total amount of mass available in the universe at that time would be exceeded if we were to add up all the stars in these galaxies. This suggests that something extraordinary is at play.
JWST's first images of the early cosmos showed about a dozen objects that looked particularly bright and red, indicating they could be massive and far away. The team then measured the amount of light each object emits in various wavelengths to determine how far away they are and how many stars they have. Six of the objects identified appear to be from no later than about 700 million years after the Big Bang, containing up to 10 billion times the mass of our sun in stars. One of them could even have the mass of 100 billion suns.
These discoveries challenge standard theories of cosmology, which suggest matter in the universe clumped together slowly, forming larger structures over time. If there are massive galaxies in the early universe, this indicates that another unknown way to form galaxies exists. Alternatively, these galaxies could host supermassive black holes in their cores, which could be devouring gas and dust, making them look like they contain a lot of stars.
To confirm the galaxies’ distances and masses, astronomers need to take more precise measurements of the galaxies' light across various wavelengths. JWST has taken spectra for a few of these galaxies already, and more are expected to come. These discoveries could rewrite our understanding of the universe's formation and growth and provide new insights into the mysteries of the cosmos.