Theory Group Seminars

Theoretical systematics in galaxy clustering in LCDM and beyond

by Eleonora Villa (Center for theoretical physics, Polish academy of science)

Europe/Rome
248 (INFN, Pisa)

248

INFN, Pisa

Description

Abstract: Theoretical systematics are known assumptions that we use in
cosmological observations, often with unknown consequences. Two possible
solutions are (i) drop the assumptions and quantify their systematic
biases or (ii) construct assumption-independent observables. We explore
both methods in different contexts.
(i) We study the impact of neglecting lensing magnification in galaxy
clustering analyses for future galaxy surveys, in the ΛCDM model and
two extensions: massive neutrinos and modified gravity. We show that the
information of the lensing convergence is significant for large-scale
test of GR and its modifications, and it concerns both the cosmological
parameters constraints and the biases in their best-fit value. We
perform a comprehensive investigation of these two effects for the
upcoming photometric and spectroscopic galaxy surveys Euclid and SKA for
different redshift binning configurations.
(ii) We consider the cosmological dynamics on sub-horizon scales and
within the quasi-static approximation allowing for a modification of
scalar perturbations with respect to the ΛCDM model. From the galaxy
and shear lensing bispectra, and all their cross-correlation, we
construct quantities that are observable without imposing any specific
parametrization for the perturbations. We also find a constraint
equation for the linear structure growth rate expressed in terms of
model-independent observables.