Abstract

Contributed Talk - Splinter Euclid

Wednesday, 20 September 2017, 17:45   (HS2)

Responses: a novel approach to the covariance of the matter power spectrum

F. Schmidt¹, A. Barreira^1
1Max Planck Institute for Astrophysics

The covariance of the matter power spectrum is an essential ingredient in the inference of cosmological information from large-scale structure data. However, due to the nonlinear nature of large-scale structure, this covariance includes a significant non-Gaussian contribution, which is challenging to predict either numerically or analytically. I will describe a recently developed novel approach which combines perturbation theory with small-volume simulations to deal with this challenge. The core underlying idea is that the impact of large-scale density fluctuations, which dominate the non-Gaussian part of the covariance, can be captured by the local response of the small-scale power spectrum to such large-scale modes. This response in turn can be calibrated accurately with relatively small cosmological simulations.