An Empirical Model For Intrinsic Alignments: Insights From Cosmological Simulations

• DOI: 10.33232/001c.118783
• Publication Date: 2024-06-04T08:29:38Z
• Authors: Nicholas Van Alfen; Duncan Campbell; Jonathan Blazek; C. Danielle Leonard; Francois Lanusse; Andrew Hearin; Rachel Mandelbaum
• Keywords: Position (finance)

We extend current models of the halo occupation distribution (HOD) to include a flexible, empirical framework for forward modeling intrinsic alignment (IA) galaxies. A primary goal this work is produce mock galaxy catalogs purpose validating existing and methods mitigation IA in weak lensing measurements. This technique can also be used new, simulation-based predictions clustering. Our model probabilistically formulated, rests upon assumption that orientations galaxies exhibit correlation with their host dark matter (sub)halo orientation or position within halo. examine necessary components phenomenology such by considering alignments between (sub)halos cosmological only simulation. then validate realistic population set simulations Illustris-TNG suite. create an HOD Illustris-like correlations using our method, constraining associated parameters, model’s those Illustris matching as closely 1.4 1.1 orientation–position orientation–orientation functions, respectively. By misalignment halo, we show 3-dimensional two-point functions simulated accurately reproduced from quasi-linear scales down . find evidence environmental influence on publicly-available software provides key component enabling efficient determination Bayesian posteriors parameters observational measurements galaxy-orientation highly nonlinear regime.