Title: The J-region Asymptotic Giant Branch (JAGB) method: An Independent Measurement of the Hubble Constant using Carbon Stars as Standard Candles
Abstract — One of the most critical unresolved issues in cosmology today is the question of whether new physics is needed beyond our current standard model, Lambda Cold Dark Matter (LCDM). In the past several years, a distinct 5-sigma tension has arisen between measurements of the Hubble constant (Ho) determined via the local Type Ia supernova distance ladder calibrated by Cepheids and from values inferred from the cosmic microwave background fluctuations. This discrepancy points to either yet-to-be discovered systematic errors in the local distance scale or a necessary revision of the LCDM model, which would indicate new physics of the Universe. In this talk, I will present an independent route to measuring Ho based on a promising new standard candle that leverages the mean NIR luminosities of carbon-rich asymptotic giant branch (AGB) stars, called the J-region asymptotic Giant Branch (JAGB) method. The JAGB method can measure distances completely independent of Cepheids and the tip of the red giant branch (TRGB). Therefore, it can provide valuable cross-checks on their distances to shed light on potential currently hidden systematic errors in the local distance scale. Furthermore, the JAGB method is less susceptible to extinction by dust and to crowding/blending effects than Cepheid variable stars. I will discuss the advantages and current uncertainties of this new standard candle. Finally, I will present a measurement of the Hubble constant derived from the JAGB method using new JWST data and discuss the implications of these results for the Hubble tension.
