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: it names recent work and was partly written without a live literature search; it awaits a check by an editor.
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.
Parent problems
- Special case of What causes the Hubble tension? · open · from revision 1 The parent was revised since revision 1: it now states another question.
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