Splashback radius and the mass accretion rate of RASS MCMF galaxy clusters

TL;DR

This paper measures the splashback radius and mass accretion rate of galaxy clusters using DES data, confirming theoretical predictions and exploring dependencies on galaxy brightness.

Contribution

It provides the first inference of the average mass accretion rate of galaxy clusters based on splashback radius measurements from DES data.

Findings

Splashback radius measured at 2.19 h^{-1} Mpc with significant steepening.

Cluster halo mass estimated at log(M_{200m}/h^{-1} M_sun) = 14.68.

Results are consistent with ΛCDM predictions.

Abstract

We present measurements of the radial profile of mass and galaxy number density around X-ray selected ROSAT All Sky Survey-Multi-Component Matched Filter galaxy clusters using Year 3 data from the Dark Energy Survey. We measure the projected cross-correlation signal of the RedMaGiC "high density" galaxies around an approximately volume-limited sample of 255 galaxy clusters at a median redshift of $z=0.4$ and an X-ray luminosity $L_X > 10^{44} \,\text{ergs} \, \text{s}^{-1} \, \text{h}^{-2}$. This cross-correlation signal measured with a signal-to-noise ratio of 16.41 allows us to infer a 3D number density profile which shows a significant steepening at the edges of these galaxy clusters, namely the splashback radius of $r_{sp}$ /$h^{-1} \mathrm{M_{\odot}} = 2.19^{+0.50}_{-0.43}$. We present the dependence of the splashback radius value over a range of absolute galaxy magnitude cuts to look for any evidence of dynamical friction affecting these results. The weak lensing signal around our galaxy clusters measured with a signal-to-noise ratio of 32.19 allows us to infer a halo mass $\text{log} (M_{\rm 200m} / h^{-1} \text{Mpc}) = 14.68_{-0.04}^{+0.04}$. Comparison of the location of the splashback radius with the spherical overdensity boundary $r_{\rm 200m}$ shows consistency with the $\mathrm{\Lambda CDM}$ predictions. We present the first inference of the average mass accretion rate of galaxy clusters using our measurements of the splashback radius.