Tod Lauer, NOIRLab
A New and Improved Image of the M87 Supermassive Black Hole
We present a new reconstruction of the Event Horizon Telescope (EHT) image of the M87 black hole from the 2017 data set. We use PRIMO (principal-component interferometric modeling), a novel machine-learning based algorithm that we developed to use high-fidelity simulations of accreting black holes as a training set. By learning the correlations between the different regions of the space of interferometric data, this approach allows us to recover high-fidelity images even in the presence of sparse coverage and reach the nominal resolution of the EHT array. This represents a significant advance in the technique of reconstructing images from interferometric data. The new black hole image comprises a thin bright ring with a diameter of 41.5 ± 0.6 μas and a fractional width that is at least a factor of two smaller than previously reported. This improvement has important implications for measuring the mass of the central black hole in M87 based on the EHT images.

Nandini Hazra, GSSI and INAF-OAAb, Italy
Surface Brightness Fluctuations (SBF) as a distance indicator in the era of Rubin
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. The SBF method is especially valuable for cosmology in the era of large surveys like Rubin, with distances accurate up to 3% measurable for tens of thousands of galaxy targets each year. One major issue in SBF studies has been the complexity of measurements, which requires extensive human input and has 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 are currently testing this procedure for analysing SBF and GCLF using data from the Subaru's Hyper Suprime Cam (HSC), and we aim to scale it up and make it accessible to the community during the operations of Rubin.