A propagator-based approach to mitigate cosmic variance in cosmological N-body simulations

Takahiro Nishimichi (Kyoto Sangyo University)

Sep 24. 2025, 10:50 — 11:10

Controlling the cosmic variance in summary statistics estimated from simulations is an important challenge for making accurate predictions of their expectation values. On large scales, perturbation-theory-based approaches, such as recent 1-loop EFT, are expected to work well. Thus, one promising direction is to construct a reasonable hybrid model combining simulations and PT. Taking advantage of the fact that the propagator -- the response of the final field to the initial field -- can be measured with little cosmic variance, we propose a possible "stitching" method that connects "tree-level" PT predictions with fully-nonlinear simulation results. This approach is applicable to biased tracers in redshift space, and the PT component incorporates important physical effects such as BAO damping and (potentially nonlinear) RSD.

Further Information
Venue:
ESI Boltzmann Lecture Hall
Associated Event:
Putting the Cosmic Large-scale Structure on the Map: Theory Meets Numerics (Workshop)
Organizer(s):
Oliver Hahn (U of Vienna)
Cornelius Rampf (RBI, Zagreb)
Cora Uhlemann (Bielefeld U)