Distances with Surface Brightness Fluctuations (SBF) and Globular Cluster Luminosity Functions (GCLF) with JWST and Roman

Analysis of Surface Brightness Fluctuations (SBF) and Globular Cluster Luminosity Functions (GCLF) in the optical band can provide extremely accurate distances up to 100 Mpc, while distances up to twice as large can be reached using near-infrared wavelengths. The SBF method is especially valuable for Cosmology in the era of large surveys, with distances accurate up to 3%. JWST will enable the extension of SBF studies up to 300 Mpc, with the expansion of both SBF and GCLF analyses into infrared wavelengths beyond the limit of ~2.2 microns covered by previous studies. We are currently testing an original procedure for analysing SBF and GCLF using JWST open-access data. The procedure has already been tested on HST/ACS data for a galaxy in the Hydra I cluster, where it was used to characterise the globular cluster population and measure the distance of PGC 087327. One major issue in SBF studies has been the complexity of measurements, which require extensive human input and have made it inaccessible as a tool for the larger community. To address this, we have developed and are currently testing a procedure that utilises entirely free and open-source tools, and performs SBF analysis with minimal human intervention. This pipeline naturally produces valuable results for globular cluster science as an auxiliary product, and has been built to adapt well across different instruments. We aim to automate this procedure for high-accuracy distance measurements, making it accessible to the community during the joint operations of Rubin, JWST, and Roman.