Dark energy, spatial curvature, and star formation efficiency from JWST photometric and spectroscopic high-redshift galaxies

TL;DR

This study uses Bayesian analysis of JWST high-redshift galaxy data to investigate whether the observed galaxy abundance indicates new physics or enhanced star formation efficiency, finding astrophysical explanations more likely.

Contribution

It provides a comprehensive Bayesian approach to constrain cosmological parameters and star formation efficiency, considering models beyond flat $ mf extit{ extLambda} CDM$.

Findings

CEERS sample yields a weak lower limit of $ m f extepsilon extgreater 0.07$

FRESCO sample requires $ m f extepsilon extgreater 0.5$ at 2$ m f extsigma$

Results are consistent across models with varying $w$ and $ m f extOmega_K$

Abstract

Early observations from the James Webb Space Telescope (JWST) have revealed an overabundance of massive high-redshift galaxies, raising the question of whether this points to new physics beyond $\Lambda$CDM, or an enhanced formation efficiency of massive stars. We revisit this issue going beyond earlier analyses based on direct comparisons to theoretical bounds at a fixed cosmology, by performing a full Bayesian analysis of the most extreme galaxies in the CEERS imaging and FRESCO spectroscopic samples, jointly constraining cosmological parameters and the baryon-to-star conversion efficiency $\epsilon$. We do so not only within the spatially flat $\Lambda$CDM model, but also in models where the dark energy equation of state $w$ and/or the spatial curvature parameter $\Omega_K$ are allowed to vary, carefully discussing the impact of both $w$ and $\Omega_K$ on the cumulative comoving stellar mass density. Within the flat $\Lambda$CDM model, once cosmological parameters are marginalized over, the CEERS sample provides a weak $2\sigma$ lower limit of $\epsilon \gtrsim 0.07$, compatible with astrophysical expectations. In contrast, the FRESCO sample requires $\epsilon \gtrsim 0.5$ at $2\sigma$, with values $\epsilon \lesssim 0.2$ disfavored at $>5\sigma$. These results do not qualitatively change when we allow $w$ and/or $\Omega_K$ to vary, with no evidence for deviations from $w=-1$ or $\Omega_K=0$. Our results therefore suggest that the origin of the ``JWST tension'' is unlikely to be cosmological, but lies in the astrophysics of galaxy formation.