JWST Measures Distances in Fornax Cluster to Address Hubble Constant Discrepancy

Recent observations from the James Webb Space Telescope (JWST) have provided new insights into the Fornax Cluster, a group of galaxies located approximately 19.3 million parsecs away. The research, titled "The TRGB-SBF Project. I. A Tip of the Red Giant Branch Distance to the Fornax Cluster with JWST," focuses on measuring the distances to three early-type galaxies within the cluster using the tip of the red giant branch (TRGB) method. This method aims to establish a more precise distance ladder that is independent of traditional methods involving Cepheid variables and Type Ia supernovae.

The study reports an average TRGB distance modulus of 31.424 ± 0.077 mag, which translates to a distance of 19.3 ± 0.7 Mpc. This measurement is part of a larger program that includes eleven additional observations of nearby elliptical galaxies, which will help refine the zero point of the Surface Brightness Fluctuations (SBF) scale to better than 2%. The implications of this work are significant, as it could lead to a high-precision measurement of the Hubble constant (H₀) that does not rely on the conventional distance ladder methods.

The findings are crucial for addressing the ongoing discrepancy in the value of the Hubble constant, which has shown differences of over 5σ significance between local measurements and those inferred from the cosmic microwave background. By developing high-precision distance measurements, this research aims to clarify whether the observed discrepancies are due to new physics or systematic errors in existing methods.

For further details, the full paper can be accessed at arXiv:2405.03743.