The Spin Alignment of Galaxies with the Large-scale Tidal Field in Hydrodynamic Simulations

Abstract

Abstract The correlation between the spins of dark matter halos and the large-scale structure (LSS) has been studied in great detail over a large redshift range, while investigations of galaxies are still incomplete. Motivated by this point, we use the state-of-the-art hydrodynamic simulation, Illustris-1, to investigate mainly the spin–LSS correlation of galaxies at a redshift of z = 0. We mainly find that the spins of low-mass, blue, oblate galaxies are preferentially aligned with the slowest collapsing direction ( ) of the large-scale tidal field, while massive, red, prolate galaxy spins tend to be perpendicular to . The transition from a parallel to a perpendicular trend occurs at ∼109.4 h −1 M ⊙ in the stellar mass, ∼0.62 in the g–r color, and ∼0.4 in triaxiality. The transition stellar mass decreases with increasing redshifts. The alignment was found to be primarily correlated with the galaxy stellar mass. Our results are consistent with previous studies both in N-body simulations and observations. Our study also fills the vacancy in the study of the galaxy spin–LSS correlation at z = 0 using hydrodynamical simulations and also provides important insight to understand the formation and evolution of galaxy angular momentum.