A Preliminary Calibration of the JAGB Method Using Gaia EDR3

TL;DR

This paper calibrates the JAGB method using Gaia EDR3 parallaxes, providing an initial zeropoint estimate for its use as an extragalactic standard candle, with plans for future improvements.

Contribution

It offers the first Gaia-based calibration of the JAGB method's zeropoint, linking it to Galactic carbon stars and comparing it with previous calibrations.

Findings

Calibrated the JAGB zeropoint to M_J = -6.14 +/- 0.05 (stat) +/- 0.11 (sys) mag.

Found good agreement with previous calibrations based on LMC and SMC distances.

Identified limitations due to Gaia EDR3 parallax uncertainties for bright, red stars.

Abstract

The recently-developed J-region Asymptotic Giant Branch (JAGB) method has extraordinary potential as an extragalactic standard candle, capable of calibrating the absolute magnitudes of locally-accessible Type Ia supernovae, thereby leading to an independent determination of the Hubble constant. Using Gaia Early Data Release 3 (EDR3) parallaxes, we calibrate the zeropoint of the JAGB method, based on the mean luminosity of a color-selected subset of carbon-rich AGB stars. We identify Galactic carbon stars from the literature and use their near-infrared photometry and Gaia EDR3 parallaxes to measure their absolute J-band magnitudes. Based on these Milky Way parallaxes we determine the zeropoint of the JAGB method to be M_J = -6.14 +/- 0.05 (stat) +/- 0.11 (sys) mag. This Galactic calibration serves as a consistency check on the JAGB zeropoint, agreeing well with previously-published, independent JAGB calibrations based on geometric, Detached-Eclipsing Binary (DEB) distances to the LMC and SMC. However, the JAGB stars used in this study suffer from the high parallax uncertainties that afflict the bright and red stars in EDR3, so we are not able to attain the higher precision of previous calibrations, and ultimately will rely on future improved DR4 and DR5 releases.