Intrinsic alignments of galaxies in the EAGLE and cosmo-OWLS simulations

Understand

We report results for the alignments of galaxies in the EAGLE and cosmo-OWLS simulations as a function of galaxy separation and halo mass.

• The combination of these hydro-cosmological simulations enables us to span four orders of magnitude in halo mass ($10.7<log_{10}(M_{200}/[h^{-1}M_\odot])<15$) and a large range of separations ($-1<log_{10}(r/[h^{-1}Mpc])< 2$).
• We focus on two classes of alignments: the orientations of galaxies with respect to either the directions to, or the orientations of, surrounding galaxies.
• We find that the strength of the alignment is a strongly decreasing function of the distance between galaxies.