Weak lensing constraints on splashback around massive clusters

TL;DR

This study investigates the splashback radius around massive galaxy clusters using weak lensing data, providing measurements of its location and density slope despite challenges from line-of-sight structures.

Contribution

First measurement of splashback radius in weak lensing data for a sample of 27 clusters, with analysis of systematic effects and modeling of the density profile.

Findings

Estimated splashback radius at 3.5 Mpc with uncertainties

Measured the density slope at splashback as approximately -4.3

Identified line-of-sight structures significantly affect lensing signals

Abstract

The splashback radius $r_\text{sp}$ separates the physical regimes of collapsed and infalling material around massive dark matter haloes. In cosmological simulations, this location is associated with a steepening of the spherically averaged density profile $\rho(r)$. In this work, we measure the splashback feature in the stacked weak gravitational lensing signal of $27$ massive clusters from the Cluster Canadian Comparison Project with careful control of residual systematics effects. We find that the shear introduced by the presence of additional structure along the line of sight significantly affects the noise at large clustercentric distances. Although we do not detect a significant steepening, the use of a simple parametric model enables us to measure both $r_\text{sp}=3.5^{+1.1}_{-0.7}$ comoving Mpc and the value of the logarithmic slope $\gamma = \log \rho / \log r$ at this point, $\gamma(r_\text{sp}) = -4.3^{+1.0}_{-1.5}$.