Clues on the origin of galactic angular momentum from looking at galaxy pairs

Abstract

We search for correlations between the spins in pairs of spiral galaxies, to study if the angular momentum gain for each galaxy was the result of tidal torques imprinted by the same tidal field. To perform our study we made use of a sample of galaxy pairs identified using the Sloan Digital Sky Survey. We find a weak, but statistically significant correlation between the spin magnitudes of neighbouring galaxies, but no clear alignment between their orientations. We show that events such as interactions with close neighbours play an important role in the value of the spin for the final configuration, as we find that these interactions tend to reduce the value of the λ spin parameter of late-type galaxies considerably, with dependence on the morphology of the neighbour. This implies that the original tidal field for each pair could have been similar, but the redistribution of angular momentum at later stages of evolution is important. © 2010 The Authors. Journal compilation © 2010 RAS.