Detection of universality of dark matter profile from Subaru weak lensing measurements of 50 massive clusters

Abstract

Abstract We develop a novel method of measuring the lensing distortion profiles of clusters by stacking the “scaled” amplitudes of background galaxy ellipticities as a function of the “scaled” centric radius according to the Navarro–Frenk–White (NFW) prediction of each cluster, based on the assumption that the different clusters in a sample follow the universalNFW profile. First we demonstrate the feasibility of this method using both the analytical NFW model and simulated halos in a suite of high-resolution N-body simulations. We then apply, as a proof of concept, this method to the Subaru weak lensing data and the XMM/Chandra X-ray observables for a sample of 50 massive clusters in the redshift range 0.15 ≤ z ≤ 0.3, where their halo masses differ from each other by up to a factor of 10. To estimate the NFW parameters of each cluster, we use the halo mass proxy relation of X-ray observables, based on either the hydrostatic equilibrium or the gas mass, and then infer the halo concentration from the model scaling relation of halo concentration with halo mass. We evaluate the performance of the NFW scaling analysis by measuring the scatters of 50 cluster lensing profiles relative to the NFW predictions over a range of radii, 0.14 ≤ R/[h−1 Mpc] ≤ 2.8. We found 4–6 σ-level evidence of the universal NFW profile in 50 clusters, for both the X-ray halo mass proxy relations, although the gas mass appears to be a better proxy of the underlying true mass. By comparing the measurements with the simulations of cluster lensing profiles taking into account the statistical errors of intrinsic galaxy shapes in the Subaru data, we argue that additional halo mass errors or intrinsic scatters of σ(M500c)/M500c ∼ 0.2–0.3 could reconcile the difference between measurements and simulations. This method allows us to some extent to preserve characteristics of individual clusters in the statistical weak lensing analysis, thereby yielding a new means of exploiting the underlying genuine form of the halo mass profile and the halo mass proxy relations via weak lensing information, under the assumption of the existence of the universal profile.