Early galaxies and early dark energy: a unified solution to the hubble tension and puzzles of massive bright galaxies revealed by JWST

JWST has revealed a large population of UV-bright galaxies at z greater than or similar to 10 and possibly overly massive galaxies at z greater than or similar to 7, challenging standard galaxy formation models in the Lambda CDM cosmology. We use an empirical galaxy formation model to explore the potential of alleviating these tensions through an Early Dark Energy (EDE) model, originally proposed to solve the Hubble tension. Our benchmark model demonstrates excellent agreement with the UV luminosity functions (UVLFs) at 4 less than or similar to z less than or similar to 10 in both Lambda CDM and EDE cosmologies. In the EDE cosmology, the UVLF measurements at z similar or equal to 12 based on spectroscopically confirmed galaxies (eight galaxies at z similar or equal to 11-13.5) exhibit no tension with the benchmark model. Photometric constraints at 12 less than or similar to z less than or similar to 16 can be fully explained within EDE via either moderately increased star-formation efficiencies (& varepsilon;(& lowast;)similar to 3-10 per cent at M-halo similar to 10(10.5)M(circle dot)) or enhanced UV variabilities (sigma(UV)similar to 0.8-1.3 mag at M-halo similar to 10(10.5)M(circle dot)) that are within the scatter of hydrodynamical simulation predictions. A similar agreement is difficult to achieve in Lambda CDM, especially at z greater than or similar to 14, where the required sigma UV exceeds the maximum value seen in simulations. Furthermore, the implausibly large cosmic stellar mass densities inferred from some JWST observations are no longer in tension with cosmology when the EDE is considered. Our findings highlight EDE as an intriguing unified solution to a fundamental problem in cosmology and the recent tensions raised by JWST observations. Data at the highest redshifts reached by JWST will be crucial for differentiating modified galaxy formation physics from new cosmological physics.