James Webb Space Telescope Feed Post

Arxiv: Early Galaxies and Early Dark Energy: A Unified Solution to the Hubble Tension and Puzzles of Massive Bright Galaxies revealed by JWST Published: 6/21/2024 9:00:01 PM Updated: 7/8/2024 5:56:45 PM

Paper abstract: JWST has revealed a large population of ultra-violet (UV)-bright galaxies atz\gtrsim 10 and possibly overly massive galaxies at z\gtrsim 7, challengingstandard galaxy formation models in the \LambdaCDM cosmology. We use anempirical galaxy formation model to explore the potential of alleviating thesetensions through an Early Dark Energy (EDE) model, originally proposed to solvethe Hubble tension. Our benchmark model demonstrates excellent agreement withthe UV luminosity functions (UVLFs) at 4<~ z <~10 in both\LambdaCDM and EDE cosmologies. In the EDE cosmology, the UVLF measurementsat z~eq 12 based on spectroscopically confirmed galaxies exhibit notension with the benchmark model. Photometric constraints at 12 <~z<~ 16 can be fully explained within EDE via either moderately increasedstar formation efficiencies (\epsilon_{\ast}~ 3-10\% at M_{\rm halo}~10^{10.5}\,{\rm M}_\odot) or enhanced UV variabilities (\sigma_{\rm UV}~0.8-1.3 mag at M_{\rm halo}~ 10^{10.5}\,{\rm M}_\odot) that are withinthe scatter of hydrodynamical simulation predictions. A similar agreement isdifficult to achieve in \LambdaCDM, especially at z\gtrsim 14, where therequired \sigma_{\rm UV} exceeds the maximum value seen in simulations.Furthermore, the implausibly large cosmic stellar mass densities inferred fromsome JWST observations are no longer in tension with cosmology when the EDE isconsidered. Our findings highlight EDE as an intriguing unified solution to afundamental problem in cosmology and the recent tensions raised by JWSTobservations. Data at the highest redshifts reached by JWST (z ~ 14-16)will be crucial for differentiating modified galaxy formation physics from newcosmological physics.