Intrinsic alignment bispectra in Stage IV galaxy surveys from first principles

Speaker: Thomas Bakx (Utrecht University) In Person and zoom

Traditionally, spectroscopic galaxy surveys have focused on obtaining cosmological information from the positions of galaxies. However, intrinsic shapes of luminous red galaxies also exhibit significant correlations with the underlying dark matter tidal field, thus offering a unique probe into 'non-scalar' phenomena such as anisotropic primordial non-Gaussianity and magnetic fields. This motivates the development of a unified perturbative theoretical framework for describing the clustering and alignment properties of galaxies on large scales. In particular, in this talk I will present recent results on modelling of intrinsic alignment bispectra in this effective field theory (EFT) framework, including their detectability in ongoing Stage-IV spectroscopic surveys such as DESI as well as comparisons to high-precision measurements of halo alignments in N-body simulations. In addition, ongoing and future weak gravitational lensing surveys aim to use three-point statistics to enhance their constraining power, implying that intrinsic alignment must be carefully modelled as a potential systematic when relating observed galaxy shapes to gravitational shear. In this spirit, I will discuss preliminary results for testing the same intrinsic alignment EFT model against measurements of three-point aperture mass statistics of galaxy catalogs from the FLAMINGO large-scale hydrodynamical simulation.