The Galaxy That Burned Out Too Soon express
The galaxy CEERS2-588 flared up like a bonfire fed with an armful of wood all at once. Just 400 million years after the Big Bang, it had already built up a mass of a billion suns and ignited countless stars. But then the fuel ran out, and over the last 10 million years, star formation in it has almost completely ceased.
The James Webb Space Telescope observed this galaxy in the infrared. Ordinary telescopes only see the ultraviolet light of young stars, but spectroscopy on Webb allowed a deeper look — into the optical range, which has shifted to infrared for us due to the expansion of the universe. Where bright hydrogen and oxygen lines were expected, there was only a flat shelf — a sign of old stars that no longer heat the gas around them.
This discovery breaks the usual picture. Previously, astronomers thought that such massive galaxies in the young universe should be star factories. CEERS2-588 shows that some galaxies flared up quickly and died out just as fast. Its chemical composition also surprised: it contains nearly as many metals (as astronomers call all elements heavier than helium) as our Sun. To produce that many metals, you need generations of stars exploding as supernovae. This means the first stars were born and died much faster than previously thought.
Original abstract
as written by the authors arXiv:2601.21833
One of the major discoveries by the James Webb Space Telescope (JWST) is the identification of a large population of luminous galaxies at $$z>10$$, challenging theoretical models for early galaxy formation. The unexpectedly high number density of these systems has triggered intense debate about potential differences in the physical properties of galaxies at such extreme redshifts and those at lower redshift. However, progress has been limited by the lack of rest-frame optical diagnostics, which are critical for constraining the key properties. Here we present deep JWST/MIRI observations of a UV-luminous galaxy at $$z=11.04$$, CEERS2-588, only 400 Myr after the Big Bang. CEERS2-588 is detected in the MIRI F560W and F770W bands, while deep MIRI/MRS spectroscopy yields no detection of H$$\alpha$$ or [OIII]$$\lambda5007$$ line, revealing a prominent Balmer break detected for the first time at $$z>10$$. Spectral energy distribution (SED) fitting indicates an extended star formation history possibly reaching $$z>15$$, followed by rapid quenching within the recent $$\sim10$$ Myr, in stark contrast to other $$z>10$$ galaxies. The MIRI detections also significantly improve our stellar mass estimate to $$\mathrm{log}(M_*/M_\odot)=9.1^{+0.1}_{-0.1}$$, making CEERS2-588 the most massive galaxy securely confirmed at $$z>10$$. Remarkably, the inferred gas-phase metallicity is near solar, exceeding predictions from current theoretical models. These results suggest that efficient starbursts play a key role in producing the abundant luminous galaxy population in the early universe.
The galaxy CEERS2-588 is so far away that its light has taken 13.5 billion years to reach us — almost the entire history of the universe.