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, $\gamma(r_\text{sp}) = -4.3^{+1.0}_{-1.5}$.
Highlights
In the concordance lambda cold dark matter ( CDM) model, collisionless dark matter acts as the building block of cosmic structure, contributing about 25 per cent of the total energy density in the Universe and the majority of the total mass (Planck Collaboration XIII 2016)
We provide a measurement1 of splashback using weak lensing observations for a sample of 27 massive clusters of galaxies that were observed as part of the Canadian Cluster Comparison Project (CCCP; Hoekstra et al 2012)
Our dataset is based on the CCCP, a survey targeting X-rayselected massive clusters at z 0.5 introduced for the first time in Hoekstra et al (2012) and re-analysed in Hoekstra et al (2015, H15 on)
Summary
In the concordance lambda cold dark matter ( CDM) model, collisionless dark matter acts as the building block of cosmic structure, contributing about 25 per cent of the total energy density in the Universe and the majority of the total mass (Planck Collaboration XIII 2016). Because the slope of the density profile at rsp is found to be, on average, a decreasing function of the halo mass, DK14 first pointed out that large overdensities are the ideal target for the detection of this feature – i.e. measuring a significant departure from the equilibrium profile. This makes galaxy clusters the ideal candidates since they correspond to the most massive haloes in the Universe. Chang et al (2018) studied a sample of redMaPPer clusters selected in Dark Energy Survey year 1 data For this large sample, they detected a splashback feature in the galaxy distribution and from weak lensing measurements.
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