Probing the neutrino mass through the cross correlation between the Rees-Sciama effect and weak lensing

Abstract

Cosmology plays a fundamental role to determine the neutrino mass, therefore also to determine its mass hierarchy, since the massive neutrino contributes to the total matter density in the Universe at the background and perturbation levels, once it becomes non-relativistic. After the non-relativistic transition the fluctuations are smashed out at the scales k ≫ kfs. Therefore, the missing fluctuation in the total matter is imprinted on the large scale structure, say the suppression of the matter power spectrum ΔP/P ≈ −8fν at the scales k ≫ kfs. In this paper, instead of considering the linear perturbation theory, which is well understood in the presence of neutrino, we propose to use the cross correlation between the Rees-Sciama effect and weak lensing to probe the neutrino mass. At the small scales, the density contrast grows faster than the background scale factor δ ∼ a, that makes a sign flipping on Φ′ ∝ ℋδ d ln (δ/a)/d ln a, which happens only in the non-linear regime. We show that the flipping scale in the cross power spectrum between the Rees-Sciama effect and weak lensing depends on the neutrino mass by assuming the shallow and deep weak lensing surveys. Our analysis shows that the Deep survey has larger signal-to-noise ratio S/N ∼ 160. Finally, we use the Fisher information matrix to forecast constraint on the neutrino mass.