Stress testing ΛCDM with high-redshift galaxy candidates

Abstract Early data from the James Webb Space Telescope (JWST) have revealed a bevy of high-redshift galaxy candidates with unexpectedly high stellar masses. An immediate concern is the consistency of these candidates with galaxy formation in the standard Λ CDM cosmological model, wherein the stellar mass ( M ⋆ ) of a galaxy is limited by the available baryonic reservoir of its host dark matter halo. The mass function of dark matter haloes therefore imposes an absolute upper limit on the number density n (> M ⋆ , z ) and stellar mass density ρ ⋆ (> M ⋆ , z ) of galaxies more massive than M ⋆ at any epoch z . Here I show that the most massive galaxy candidates in JWST observations at z ≈ 7–10 lie at the…

• NS
  National Science Foundation

  Awards: AST-1910346, AST-2108962, AST-1752913, 80NSSC22K0827, 1910346, HST-GO-16226, HST-GO-15658, AR-15809, HST-AR-15809, 2108962, CAREER, GO-15902, HST-AR-16159, HST-GO-15902, HST-GO-15901
• NA
  National Aeronautics and Space Administration

  Awards: HST-GO-15902, HST-AR-15809, HST-GO-15901, NASA contract NAS5-26555, HST-GO-16226, NAS5-26555, GO-15902, 80NSSC22K0827, AR-15809, AST-1910346, AST-2108962, HST-GO-15658, AST-1752913, HST-AR-16159
• UO
  University of Texas at Austin
• ST
  Space Telescope Science Institute

  Awards: AR-15809, NAS5-26555, HST-GO-16226, HST-AR-16159, HST-GO-15901, GO-15902, 26555, HST-GO-15902, HST-AR-15809
• NS
  Nuclear Safety and Security Commission