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. Barreira1
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.