Grouping Galaxies with a New Probabilistic Algorithm

We present a new algorithm for grouping galaxies in redshift space that is designed to connect them to the dark matter haloes in which they reside. The algorithm adopts an assumed stellar-to-halo mass relation with scatter to probabilistically assign halo masses to galaxies. The algorithm then uses a spherical over-density approach to group centrals and satellites together, taking redshift distortions into account in a probabilistic way. Uncertainties in group finding can be easily quantified by running several realizations of the algorithm. We present tests of our algorithm on mock galaxy catalogues in order to assess its efficacy. Our future goal is to apply the algorithm to actual observational data, compare against other group-finding methods, and publicly release the code.