JWST and VLT Quadruple Early Galaxy Mass Estimates in 9-Galaxy IMF Study

3 articles · Updated · Nature.com · Aug 20

Nine massive quiescent galaxies studied with JWST and the VLT show excess low-mass stars, indicating bottom-heavy initial mass functions rather than a Milky Way-like stellar mix.
That shift matters because low-mass stars hold most of a galaxy’s stellar mass but are hard to see directly, so standard assumptions had likely understated distant galaxies’ true masses.
The oldest object in the sample—formed at redshift above 5—showed the strongest bottom-heavy signature, linking it to JWST’s earlier “impossibly early” galaxy population.
For those early galaxies, the team says stellar masses could rise by about 4 ± 1 times, worsening the mismatch between observations and galaxy-formation models that already struggle to explain rapid early buildup.