The mass and galaxy distribution around SZ-selected clusters

Abstract

We present measurements of the radial profiles of the mass and galaxy number density around Sunyaev-Zel’dovich (SZ)-selected clusters using both weak lensing and galaxy counts. The clusters are selected from the Atacama Cosmology Telescope Data Release 5 and the galaxies from the Dark Energy Survey Year 3 dataset. With signal-to-noise of 62 (45) for galaxy (weak lensing) profiles over scales of about 0.2 − 20h−1 Mpc, these are the highest precision measurements for SZ-selected clusters to date. Because SZ selection closely approximates mass selection, these measurements enable several tests of theoretical models of the mass and light distribution around clusters. Our main findings are: 1. The splashback feature is detected at a consistent location in both the mass and galaxy profiles and its location is consistent with predictions of cold dark matter N-body simulations. 2. The full mass profile is also consistent with the simulations. 3. The shapes of the galaxy and lensing profiles are remarkably similar for our sample over the entire range of scales, from well inside the cluster halo to the quasilinear regime. We measure the dependence of the profile shapes on the galaxy sample, redshift and cluster mass. We extend the Diemer & Kravtsov model for the cluster profiles to the linear regime using perturbation theory and show that it provides a good match to the measured profiles. We also compare the measured profiles to predictions of the standard halo model and simulations that include hydrodynamics. Applications of these results to cluster mass estimation, cosmology and astrophysics are discussed.

Snowmass2021 Cosmic Frontier White Paper: Dark Matter Physics from Halo Measurements

“…Through a combination of data from optical, CMB, and X-ray surveys, it is now possible to accurately measure the stacked weak lensing profiles around massive galaxy clusters (M 10 13.5 M /h) [312,313]. The signal-to-noise is expected to increase significantly in the next decade as the next generation optical (e.g.…”

A dynamics-based density profile for dark haloes. I. Algorithm and basic results

“…The halo outskirts (r > ∼ 0.5 R vir ) have recently received renewed attention because they turn out to be sensitive to otherwise inaccessible halo properties such as the mass accretion rate (Diemer & Kravtsov 2014, hereafter DK14; see also Xhakaj et al 2020Xhakaj et al , 2021, the nature of dark matter (Banerjee et al 2020), and deviations from General Relativity (Adhikari et al 2018;Contigiani et al 2019a). At the same time, rapid observational progress has led to high-accuracy constraints on profiles from profiles of satellites in individual clusters (Rines et al 2013;Tully 2015;Patej & Loeb 2016), in stacked clusters (More et al 2016;Baxter et al 2017;Nishizawa et al 2018;Zürcher & More 2019;Murata et al 2020), and in weak lensing profiles (Mandelbaum et al 2006;Umetsu et al 2011;Umetsu & Diemer 2017;Contigiani et al 2019b;Chang et al 2018;Shin et al 2019Shin et al , 2021. Deviations from simple fitting functions for the orbiting profile have long been known to bias weak lensing masses (Becker & Kravtsov 2011;Oguri & Hamana 2011), but the recently acquired high signal-to-noise in the outer profiles has made detailed theoretical modelling even more pressing.…”

A dynamics-based density profile for dark haloes -- II. Fitting function

“…For the first time, we can rely on profiles that have been dynamically split into orbiting and infalling particles (using the algorithm presented in Diemer 2022, hereafter Paper I). Similar splits have recently been explored in observational data using galaxy properties such as color (Baxter et al 2017;Adhikari et al 2021;O'Donnell et al 2021;Shin et al 2021;Aung et al 2022;Dacunha et al 2022;O'Neil et al 2022), necessitating a fitting function that captures the shapes of the orbiting and infalling terms. We require that this fitting function should 1) describe the profiles accurately even in the transition region, 2) be flexible enough to apply to individual halos and to stacks with different selection criteria, 3) work across all halo masses, redshifts, cosmologies, and accretion rates, 4) rely on as few free parameters as possible with clear, physical interpretations, and 5) exhibit minimal parameter degeneracies.…”

“…Some observational works have extrapolated this shape based on DK14 fits (e.g. Baxter et al 2017;Shin et al 2021), but it is not clear that the results are physically meaningful. Third, the slope of the DK14 profile is a complex function, which makes it difficult to establish the relationship between the profile parameters and physical features such as the splashback radius.…”