Cosmic accretion shocks as a tool to measure the dark matter mass of galaxy clusters

TL;DR

This paper proposes a new method to estimate galaxy cluster dark matter mass using properties of cosmological accretion shocks, potentially providing an independent and accurate measurement within the standard cosmological model.

Contribution

It introduces a novel relation between cluster mass, shock radius, and Mach number, enabling dark matter mass estimation from observable shock features.

Findings

Clusters lie on a plane in mass, shock radius, and Mach number space.

Dark matter mass can be estimated with about 30% error using shock observations.

Method offers an independent constraint on the $\\Lambda$CDM model.

Abstract

Cosmological accretion shocks created during the formation of galaxy clusters are a ubiquitous phenomenon all around the Universe. These shocks, and their features, are intimately related with the gravitational energy put into play during galaxy cluster formation. Studying a sample of simulated galaxy clusters and their associated accretion shocks, we show that objects in our sample sit in a plane within the three dimensional-space of cluster total mass, shock radius, and Mach number (a measure of shock intensity). Using this relation, and considering that forthcoming new observations will be able to measure shock radii and intensities, we put forward the idea that the dark matter content of galaxy clusters could be indirectly measured with an error up to around 30 per cent at the $1\sigma$ confidence level. This procedure would be a new and independent method to measure the dark matter mass in cosmic structures, and a novel constraint to the accepted $\Lambda$CDM paradigm.