The Dark Matter Halo Finder

The galaxies we see in the sky are only a small part of the material that makes up the universe. The vast majority of matter is “dark matter,” and each galaxy forms, lives, and dies in a massive clump of dark matter. Thus, the dark matter must have a profound influence on creating the diverse population of galaxies that we see today. Since dark matter isn’t directly observable, understanding this influence requires new methods to indirectly measure the connection between the dark matter and the galaxies that we see. Scientists at New York University will develop a new statistical method for quantifying this relationship and will apply it to data from the Bright Galaxy Survey of the Dark Energy Spectroscopic Instrument (DESI). As part of this project, the PI will advise undergraduate students in research and will incorporate results from this research into undergraduate coursework. The technique in this proposal is to use a galaxy group finder that assumes that all groups live in a common dark matter halo, and that the population of dark halos is well-predicted by numerical simulations of structure formation. The properties and formation histories of halos is imparted on their spatial distribution, thus it is possible to map the observed properties of galaxies back onto the unobservable properties of dark matter halos in an iterative process, converging on a correlation matrix between halo properties and galaxy properties. This project will use new data from the DESI Bright Galaxy Survey, nearly a factor of ten larger than the SDSS spectroscopic catalog, to break new ground in our understanding of the influence of the dark sector on galaxy formation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.