Reconstructing the kinematics of Laniakea using Type Ia Supernovae

Abstract

We develop a kinematic framework that relates the monopole, dipole, and quadrupole of the luminosity distance to an ellipsoidal peculiar velocity field describing the dynamics of the Laniakea supercluster. By properly accounting for the transformations between the CMB and Laniakea reference frames and selecting Type Ia supernovae within the volume associated with the superstructure, we show that luminosity distance multipoles encode the expansion and shear of the local velocity field. This allows the ellipsoidal kinematics of Laniakea to be inferred directly from supernova observations. Our results provide a physically motivated interpretation of luminosity distance anisotropies within the volume dynamically dominated by Laniakea as signatures of its large-scale kinematics. The framework developed here suggests that future supernova observations can enable the independent reconstruction of large-scale structures in the local Universe