According to the James Webb Space Telescope, which has only been observing the sky for a few weeks, there are tens, hundreds, or even 1000 times more bright galaxies at the edge of space-time (soon after the big bang) than astronomers predicted.
“No one expected anything like this,” says University of Texas at Austin’s Michael Boylan-Kolchin. “Galaxies are exploding out of nowhere,” says Flatiron Institute’s Rachel Somerville.
Because gas clouds are thought to condense much more slowly than Webb’s galaxy-rich photos of the early universe, taken less than 500 million years after the big bang, galaxy formation models may need to be revised.
According to Garth Illingworth of the University of California (UC), Santa Cruz, this is “way outside the box” of what the models predicted.
The NASA-led Webb orbiting observatory, which also received funding from the Canadian and European space agencies, began taking observations late in June from its vantage point 1.5 million kilometres above Earth.
It has spent the majority of its time so far working on demonstration projects such as the Cosmic Evolution Early Release Science (CEERS) Survey. The Webb Space Telescope is designed to go deeper into cosmic history than the Hubble Space Telescope.
The James Webb Space Telescope photographed this galaxy from an unprecedented distance. CLARA POLLOCK/SOPHIE JEWELL
Webb’s 6.5-meter mirror, which has six times the area of Hubble’s and operates at infrared wavelengths, makes it more sensitive to such distant sources, whose light is stretched to longer, redder wavelengths by cosmic expansion.
Webb discovered a candidate galaxy within days of beginning its observations, which would have been the most distant object ever observed if it had been visible when the universe was only 230 million years old, or 1.7% of its current age.
Since then, surveys have revealed that the object is just one of a dazzling array of early galaxies, each of which is modest by modern standards but has a higher luminosity than expected.
Some scientists warn that the abundance may be a mirage based on photos of a small piece of sky. Boylan-Kolchin wonders if Webb “lucked out” when he looked into a massive cluster of galaxies that was denser than the rest of the early universe.
That question will be answered when CEERS expands its scope later this year and the results of additional comprehensive surveys are available.
Webb’s early scientific teams discovered a few of these posing galaxies, as reported in a number of recent preprints. If the abundance of early galaxies is real, astronomers may have to fundamentally rethink galaxy formation or the dominant cosmology.
According to Charlotte Mason of the Niels Bohr Institute, Hubble research has revealed that star formation has occurred at a relatively consistent rate for up to 600 million years after the big bang. However, the Webb data indicate that it was moving at a much faster rate in previous eras—so quickly, in fact, that gas clouds were collapsing without any restraint from heat or supernovae.
Indeed, Tommaso Treu of the University of California, Los Angeles, who leads the GLASS Webb survey, claims that his team is seeing these young galaxies “form stars like crazy.” “They look like giant balls of star formation and nothing else,” he adds.
James Webb has already broken numerous astronomical records, and we can’t wait to see what happens next.
