The mass accretion rate of galaxy clusters: a measurable quantity

TL;DR

This paper proposes a method to measure the mass accretion rate of galaxy clusters from their mass profiles beyond the virial radius, offering a new observational test for cosmological models.

Contribution

It introduces a novel observational approach to estimate galaxy cluster accretion rates from mass profiles, validated against N-body simulations.

Findings

Estimated accretion rates are within 20-40% of simulation-based rates.

The method is feasible for observational data across redshifts 0 to 2.

Provides a new way to test cosmological and structure formation theories.

Abstract

We are interested in investigating the growth of structures at the nonlinear scales of galaxy clusters from an observational perspective: we explore the possibility of measuring the mass accretion rate of galaxy clusters from their mass profile beyond the virial radius. We derive the accretion rate from the mass of a spherical shell whose infall velocity is extracted from $N$-body simulations. In the redshift range $z=[0,2]$, our prescription returns an average mass accretion rate within $20-40 \%$ of the average rate derived from the merger trees of dark matter haloes extracted from $N$-body simulations. Our result suggests that measuring the mean mass accretion rate of a sample of galaxy clusters is actually feasible, thus providing a new potential observational test of the cosmological and structure formation models.