Stress testing ΛCDM with high-redshift galaxy candidates

Area of Science:

• Cosmology
• Galaxy Formation and Evolution
• Astrophysics

Background:

• Early data from the James Webb Space Telescope (JWST) reveal high-redshift galaxy candidates with high stellar masses.
• The standard Lambda Cold Dark M atter (ΛCDM) model posits that galaxy stellar mass is limited by the baryonic reservoir of its host dark matter halo.

Purpose of the Study:

• To assess the consistency of JWST-identified high-redshift galaxy candidates with the ΛCDM cosmological model.
• To investigate potential issues with observed galaxy properties, early galaxy formation theories, or the ΛCDM model itself.

Main Methods:

• Comparison of observed stellar masses of high-redshift galaxy candidates with theoretical upper limits imposed by the dark matter halo mass function within the ΛCDM model.
• Analysis of number density and stellar mass density of galaxies at z ≈ 7-10.

Main Results:

• The most massive galaxy candidates identified by JWST at z ≈ 7-10 are at the extreme upper limits of predicted stellar masses within the ΛCDM model.
• This suggests a potential tension between JWST observations and the standard cosmological model.

Conclusions:

• The high stellar masses of early JWST galaxies present a significant challenge to the standard ΛCDM cosmology or our understanding of early galaxy formation.
• Further investigation is required to resolve the discrepancy between observations and theoretical predictions.