Cosmography of Laniakea: Type Ia supernovae, Peculiar Velocities & Dark Matter

The expansion rate of the universe parameterized by the Hubble constant is not constant, but rather varies with cosmic time following the deceleration and acceleration of the Universe. Locally, the smooth Hubble expansion velocities are altered due to gravitational perturbations of the underlying density field of matter. The study of such peculiar velocities therefore provides a means to construct a 3-D peculiar velocity map of normal baryonic matter from which the underlying density and distribution of Dark Matter (DM) throughout our home supercluster Laniakea can be inferred. Our pilot project will leverage the utility of Type-Ia supernovae as precise cosmological distance indicators to expand upon our current cosmography of Laniakea. If successful, we plan to pursue a scaled up version that will ultimately enable us to identify the location of the major DM concentration driving our peculiar motion relative to the smooth Hubble expansion and expand our understanding of how DM clusters on small scales.