Threepoint intrinsic alignments of dark matter haloes in the IllustrisTNG simulation
Abstract
We use the IllustrisTNG suite of cosmological simulations to measure intrinsic alignment (IA) bispectra of dark matter subhaloes between redshifts 0 and 1. We decompose the intrinsic shear field into E and B modes and find that the bispectra B_{δδE} and B_{δEE}, between the matter overdensity field, δ, and the Emode field, are detected with high significance. We also model the IA bispectra analytically using a method consistent with the twopoint nonlinear alignment model. We use this model and the simulation measurements to infer the IA amplitude A_{IA} and find that values of A_{IA} obtained from IA power spectra and bispectra agree well at scales up to $k_\mathrm{max}= 2 \, h \mathrm{Mpc}^{1}$. For example at z = 1, A_{IA} = 2.13 ± 0.02 from the cross power spectrum between the matter overdensity and Emode fields and A_{IA} = 2.11 ± 0.03 from B_{δδE}. This demonstrates that a single physically motivated model can jointly model twopoint and threepoint statistics of IAs, thus enabling a cleaner separation between IAs and cosmological weak lensing signals.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 2022
 DOI:
 10.1093/mnras/stac2351
 arXiv:
 arXiv:2204.10342
 Bibcode:
 2022MNRAS.516.1829P
 Keywords:

 gravitational lensing: weak;
 methods: numerical;
 largescale structure of Universe;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 Consistent with version published in MNRAS