A double take on early and interacting dark energy from JWST

Understand

The very first light captured by the James Webb Space Telescope (JWST) revealed a population of galaxies at very high redshifts more massive than expected in the canonical $\Lambda$CDM model of structure formation.

• Barring, among others, a systematic origin of the issue, in this paper, we test alternative cosmological perturbation histories.
• We argue that models with a larger matter component $\Omega_m$ and/or a larger scalar spectral index $n_s$ can substantially improve the fit to JWST measurements.
• In this regard, phenomenological extensions related to the dark energy sector of the theory are appealing alternatives, with Early Dark Energy emerging as an excellent candidate to explain (at least in part) the unexpected JWST preference for larger stellar mass densities.