Advances in constraining intrinsic alignment models with hydrodynamic simulations

ABSTRACT We use galaxies from the illustristng, massiveblack-ii, and illustris-1 hydrodynamic simulations to investigate behaviour of large scale galaxy intrinsic alignments. Our analysis spans four redshift slices over approximate range contemporary lensing surveys z = 0?1. construct comparable weighted samples three simulations, which we then analyse using an alignment model that includes both linear quadratic contributions. data vector galaxy–galaxy, galaxy–shape, shape–shape projected correlations, with joint covariance matrix estimated analytically. In all report non-zero IAs at level several ?. For a fixed lower mass threshold, find relatively strong dependence in IA amplitude increasing by factor ?2 between redshifts 0 1. no significant evidence for values tidal torquing amplitude, A2, TNG, above statistical uncertainties, although MBII favours moderately negative A2 ? ?2. Examining properties TATT as function colour, luminosity type (satellite or central), our findings are consistent most recent measurements on real data. also outline novel method constraining parameters directly pixelized field, alongside proof-of-concept exercise TNG. This technique is shown be promising, comparison previous results obtained via other methods non-trivial.