Kavli Affiliate: Mark Vogelsberger
| First 5 Authors: Xuejian Shen, Xuejian Shen, , ,
| Summary:
Early JWST observations have revealed a high-redshift universe more vibrant
than predicted by canonical galaxy-formation models within $Lambda$CDM,
showing an excess of ultraviolet(UV)-bright, massive, and morphologically
mature galaxies. Departures from $Lambda$CDM prior to recombination can
imprint signatures on non-linear structure formation at high redshift. In this
paper, we investigate one such scenario – Early Dark Energy, originally
proposed to resolve the Hubble tension – and its implications for these
high-redshift challenges. We present the first large-scale cosmological
hydrodynamic simulations of these models. Modifications to the
pre-recombination expansion history accelerate early structure formation and
produce UV luminosity and stellar mass functions in excellent agreement with
JWST measurements, requiring essentially no additional calibrations.
Predictions converge to $Lambda$CDM at lower redshifts ($z lesssim 3$),
thereby preserving all successes of $Lambda$CDM. This model also accelerates
the emergence of stellar and gaseous disks, increasing their number densities
by $sim 0.5$ dex at $zsimeq 6$-7, primarily due to the higher abundance of
massive galaxies. Taken together, these results demonstrate how early-universe
physics can simultaneously reconcile multiple high-redshift challenges and the
Hubble tension while retaining the core achievements of $Lambda$CDM. This
opens a pathway to constraining a broad class of beyond-$Lambda$CDM models
with forthcoming observations.
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