The cosmic timeline implied by the JWST high-redshift galaxies

Abstract

The so-called impossibly early galaxy problem, first identified via the Hubble Space Telescope's observation of galaxies at redshifts z > 10, appears to have been exacerbated by the more recent JWST discovery of galaxy candidates at even higher redshifts (z ∼17) which, however, are yet to be confirmed spectroscopically. These candidates would have emerged only ∼230 Myr after the big bang in the context of Lambda cold dark matter (ΛCDM), requiring a more rapid star formation in the earliest galaxies than appears to be permitted by simulations adopting the concordance model parameters. This time-compression problem would therefore be inconsistent with the age-redshift relation predicted by ΛCDM. Instead, the sequence of star formation and galaxy assembly would confirm the timeline predicted by the Rh = ct universe, a theoretically advanced version of ΛCDM that incorporates the 'zero active mass' condition from general relativity. This model has accounted for many cosmological data better than ΛCDM, and eliminates all of its inconsistencies, including the horizon and initial entropy problems. The latest JWST discoveries at z ≳ 14, if confirmed, would add further support to the idea that the Rh = ct universe is favoured by the observations over the current standard model. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.