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

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 at stake 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% at the 1σ 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 cold dark matter paradigm.