Creating a New Distance Ladder with Surface Brightness Fluctuations

Disagreements between values of the Hubble constant (H0) measured locally and calculated from the ΛCDM model have created a "crisis in cosmology." Many current observational methods to measure distances into the Hubble flow rely on the same set of standard candles and zero-point measurements. In order to decrease systematic uncertainties we are creating a new and independent distance ladder using the James Webb Space Telescope to measure the tip of the red giant branch stars in 14 giant elliptical galaxies. These galaxies can then be used as calibrators for surface brightness fluctuation (SBF) distances and replace the rung on the ladder previously occupied by Cepheid variable stars. We are measuring the distances to over two hundred elliptical galaxies with the Hubble Space Telescope by using SBF. We are reassessing all of our galaxies with a newly developed python pipeline to reduce systematic uncertainties and human biases in our data. I have been using our new pipeline with past and current galaxies to create a relation between color measurements. The new SBF distances will make use of the JWST TRGB zero point and give a new estimate of H0 based on IR SBF distances.