The Highest-redshift Balmer Breaks as a Test of ΛCDM
Abstract
Recent studies have reported tension between the presence of luminous, high-redshift galaxies and the halo mass functions predicted by standard cosmology. Here, an improved test is proposed using the presence of high-redshift Balmer breaks to probe the formation of early 104–105 M ⊙ baryonic minihalos. Unlike previous tests, this does not depend upon the mass-to-light ratio and has only a slight dependence upon the metallicity, stellar initial mass function, and star formation history, which are all weakly constrained at high redshift. We show that the strongest Balmer breaks allowed at z = 9 using the simplest ΛCDM cosmological model would allow a D 4000 as high as 1.26 under idealized circumstances and D 4000 ≤ 1.14 including realistic feedback models. Since current photometric template fitting to JWST sources infers the existence of stronger Balmer breaks out to z ≳ 11, upcoming spectroscopic follow-up will either demonstrate those templates are invalid at high redshift or imply new physics beyond "vanilla" ΛCDM.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2024
- DOI:
- 10.3847/1538-4357/ad3afb
- arXiv:
- arXiv:2305.15459
- Bibcode:
- 2024ApJ...967..172S
- Keywords:
-
- Galaxy spectroscopy;
- Galaxies;
- Quenched galaxies;
- 2171;
- 573;
- 2016;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 10 pages, 5 figures