The velocity structure of the Intracluster Medium of the Centaurus cluster

TL;DR

This study uses advanced X-ray calibration techniques to map the velocity structure of the intracluster medium in the Centaurus cluster, revealing its relation to galaxy motions and the energetic contribution of kinetic motions.

Contribution

It provides the first detailed 2D velocity maps of the ICM in the Centaurus cluster with unprecedented accuracy using a new calibration method.

Findings

ICM velocity structure aligns with galaxy motions.

Cold fronts move perpendicular to our line of sight with low velocity.

Kinetic energy contributes less than 25% to total energy beyond 30 kpc.

Abstract

There are few direct measurements of ICM velocity structure, despite its importance for understanding clusters. We present a detailed analysis of the velocity structure of the Centaurus cluster using XMM-Newton observations. Using a new EPIC-pn energy scale calibration, which uses the Cu Ka instrumental line as reference, we are able to obtain velocity measurements with uncertainties down to $\Delta v \sim 79$ km/s. We create 2D spectral maps for the velocity, metallicity, temperature, density, entropy and pressure with an spatial resolution of 0.25'. We have found that the velocity structure of the ICM is similar to the velocity structure of the main galaxies while the cold fronts are likely moving in a plane perpendicular to our line of sight with low velocity. Finally, we have found a contribution from the kinetic component of <25\% to the total energetic budget for radius $>30$ kpc.