COSMO In the literature: contested

Do TRGB, JAGB and Cepheid ladders give the same Hubble constant?

In plain words

Distances to nearby galaxies can be calibrated with pulsating stars (Cepheids), the brightest old red giant stars, or carbon-rich giant stars. These methods should agree if none has a hidden bias.

Precise statement

Using one JWST sample of type Ia supernova host galaxies, determine the mean distance-modulus offsets between Cepheid, tip of the red giant branch (TRGB) and J-region asymptotic giant branch (JAGB) calibrations, and the resulting h from each. An answer is each offset with uncertainty below 0.02 mag and an explanation of any nonzero offset.

What would settle it

A shared, blinded JWST analysis of the same hosts by independent teams with identical supernova samples.

Status in the literature

Unverified note

CCHP (Freedman et al. 2025, arXiv:2408.06153) obtained $h = 0.704 \pm 0.012\,(\mathrm{stat}) \pm 0.013\,(\mathrm{sys})$ from TRGB with 24 supernova calibrators, and from JWST data alone $h = 0.688\,(\mathrm{TRGB})$ and $0.678\,(\mathrm{JAGB})$, while SH0ES reports mean method differences near $0.03\,\mathrm{mag}$ and $h$ near 0.73.