Insights from HST into Ultramassive Galaxies and Early-Universe Cosmology
Abstract
The early-science observations made by the James Webb Space Telescope (JWST) have revealed an excess of ultramassive galaxy candidates that appear to challenge the standard cosmological model (Λ CDM ). Here, we argue that any modifications to Λ CDM that can produce such ultramassive galaxies in the early Universe would also affect the UV galaxy luminosity function (UV LF) inferred from the Hubble Space Telescope (HST). The UV LF covers the same redshifts (z ≈7 - 10 ) and host-halo masses (Mh≈1010- 1012M⊙ ) as the JWST candidates, but tracks star-formation rate rather than stellar mass. We consider beyond-Λ CDM power-spectrum enhancements and show that any departure large enough to reproduce the abundance of ultramassive JWST candidates is in conflict with the HST data. Our analysis, therefore, severely disfavors a cosmological explanation for the JWST abundance problem. Looking ahead, we determine the maximum allowable stellar-mass function and provide projections for the high-z UV LF given our constraints on cosmology from current HST data.
- Publication:
-
Physical Review Letters
- Pub Date:
- February 2024
- DOI:
- 10.1103/PhysRevLett.132.061002
- arXiv:
- arXiv:2305.07049
- Bibcode:
- 2024PhRvL.132f1002S
- Keywords:
-
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- High Energy Physics - Phenomenology
- E-Print:
- 10 pages, 5 figures - v2: Matches version accepted for publication in PRL