Résumé / Abstract Journal-club_Univers

Journal-club Univers / Journal-club Universe

« Weak gravitational lensing as a (3D) probe of gravity »

Alessio Spurio Mancini
Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg (Heidelberg, Allemagne)

Cosmic shear, the weak gravitational lensing effect caused by the large-scale structure, is one of the primary probes to test gravity on cosmological scales with current and future surveys. In particular, cosmic shear is sensitive to both standard GR cosmological parameters and those that describe modified theories of gravity, such as those belonging to the Horndeski class. These models include the majority of universally coupled extensions to ?CDM with one scalar degree of freedom in addition to the metric, which are still in agreement with current observations.
In this talk I will discuss some aspects concerning the constraining power of current and future cosmic shear datasets on this broad class of theories. I will compare in particular two main techniques to analyse a cosmic shear survey: a tomographic method, where correlations between the lensing signal in different redshift bins are used to recover redshift information, and a 3D approach, where the full redshift information is carried through the entire analysis. Due to its increased amount of redshift information, a future 3D analysis can constrain both standard gravity and Horndeski theories better than a tomographic one, in particular with a decrease in the errors on the Horndeski parameters of the order of 20%.
vendredi 4 mai 2018 - 14:00
Salle 281, Institut d'Astrophysique
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