title: Testing gravity with the stacked phase space around galaxy clusters.
abstract: In general relativity, the average velocity field of dark matter around galaxy clusters is uniquely determined by the mass profile. The latter can be measured through weak lensing. We propose a new method of measuring the velocity field (phase space density) by stacking redshifts of surrounding galaxies from a spectroscopic sample. In combination with lensing, this yields a direct test of gravity on scales of 1-30 Mpc. Using N-body simulations, we show that this method can improve upon current constraints on f(R) and Dvali-Gabadadze-Porrati model parameters by several orders of magnitude when applied to upcoming imaging and redshift surveys.
authors.affiliation: Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Chiba, Japan.
authors.forename: Tsz Yan
authors.initials: TY
authors.lastname: Lam
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nishimichi
authors.forename: Fabian
authors.initials: F
authors.lastname: Schmidt
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takada