The TRGB-SBF Project. IV. A Color Calibration of the TRGB in the JWST F090W+F150W Filters

TL;DR

This paper presents a new calibration of the TRGB in JWST F090W+F150W filters, improving galaxy distance measurements by accounting for metallicity effects and providing revised distance estimates.

Contribution

It introduces a color calibration for the TRGB in JWST filters, enabling more precise galaxy distance measurements considering metallicity variations.

Findings

TRGB absolute magnitude in F090W is -4.40 mag for certain colors.

Calibration applied to 16 galaxies yields slightly closer distances than previous estimates.

Theoretical isochrones match observed TRGB color-metallicity relations.

Abstract

Observations with JWST in the F090W band provide a powerful tool for determining galaxy distances based on tip of the red giant branch (TRGB) measurements. It is a great convenience that the TRGB lies at an almost constant absolute magnitude level at low metallicities. However, the TRGB becomes fainter at high metallicities in the F090W filter. Details of this break in slope are critical for precision applications in the acquisition of distances. With an absolute scaling set by the maser distance to NGC 4258 (but excluding the uncertainty in that distance), the value $M^\mathrm{TRGB}_\mathrm{F090W} = -4.40 \pm 0.03$ mag (traditional Vega) is found for $(\mathrm{F090W}-\mathrm{F150W})_0<1.65$ mag. The theoretical RGB isochrone that reaches the color 1.65 at the RGB tip corresponds to metallicity $[M/H] = -0.57$ for a 10 Gyr population. The calibration is used to derive distances for 16 galaxies relative to the megamaser host NGC 4258. Revised distances are on average slightly closer than literature values derived from the same data.