Cosmological Constraints on Neutrino Masses in Light of JWST Red and Massive Candidate Galaxies

Abstract The overabundance of the red and massive candidate galaxies observed by the James Webb Space Telescope (JWST) implies efficient structure formation or large star formation efficiency at high redshift z ∼ 10. In the scenario of a low or moderate star formation efficiency, because massive neutrinos tend to suppress the growth of structure of the universe, the JWST observation tightens the upper bound of the neutrino masses. Assuming Λ cold dark matter cosmology and a star formation efficiency ∈0.05, 0.3 (flat prior), we perform joint analyses of Planck+JWST and Planck+BAO+JWST, and obtain improved constraints ∑ m ν < 0.196 eV and ∑ m ν < 0.111 eV at 95% confidence level, respectively. Based on the above assumptions, the inverted mass ordering, which implies ∑ m ν ≥ 0.1eV, is excluded by Planck+BAO+JWST at 92.7% confidence level.