Cold Fronts and Shocks Formed by Gas Streams in Galaxy Clusters

TL;DR

This study uses hydro-cosmological simulations to reveal that persistent inflowing gas streams, not just galaxy mergers, can generate multiple cold fronts and shocks in galaxy cluster cores over billions of years.

Contribution

It introduces a new mechanism for cold front and shock formation in galaxy clusters via long-lasting gas stream inflows, expanding understanding beyond merger events.

Findings

Gas stream collisions can produce shocks and cold fronts.

Inflow persists over several billion years.

Multiple cold fronts can form from continuous streams.

Abstract

Cold Fronts and shocks are hallmarks of the complex intra-cluster medium (ICM) in galaxy clusters. They are thought to occur due to gas motions within the ICM and are often attributed to galaxy mergers within the cluster. Using hydro-cosmological simulations of clusters of galaxies, we show that collisions of inflowing gas streams, seen to penetrate to the very centre of about half the clusters, offer an additional mechanism for the formation of shocks and cold fronts in cluster cores. Unlike episodic merger events, a gas stream inflow persists over a period of several Gyrs and it could generate a particular pattern of multiple cold fronts and shocks.