The Hot and Energetic Universe: The astrophysics of galaxy groups and clusters

TL;DR

This paper discusses how Athena+ X-ray observatory will revolutionize our understanding of galaxy clusters and the cosmic web by studying the hot plasma and baryonic processes involved in large-scale structure formation.

Contribution

It highlights the potential of Athena+ to address fundamental questions about the physics and evolution of galaxy clusters and the intergalactic medium.

Findings

Athena+ will measure motions and turbulence in the intracluster medium.

It will resolve accreting regions spatially and spectroscopically.

The mission aims to understand the formation and evolution of cosmic structures.

Abstract

As the nodes of the cosmic web, clusters of galaxies trace the large-scale distribution of matter in the Universe. They are thus privileged sites in which to investigate the complex physics of structure formation. However, the complete story of how these structures grow, and how they dissipate the gravitational and non-thermal components of their energy budget over cosmic time, is still beyond our grasp. Fundamental questions such as How do hot diffuse baryons accrete and dynamically evolve in dark matter potentials? How and when was the energy that we observe in the ICM generated and distributed? Where and when are heavy elements produced and how are they circulated? are still unanswered. Most of the cluster baryons exists in the form of a diffuse, hot, metal-enriched plasma that radiates primarily in the X-ray band (the intracluster medium, ICM), allowing the X-ray observations of the evolving cluster population to provide a unique opportunity to address these topics. Athena+ with its large collecting area and unprecedented combination of high spectral and angular resolution offers the only way to make major advances in answering these questions. Athena+ will show how the baryonic gas evolves in the dark matter potential wells by studying the motions and turbulence in the ICM. Athena+ will be able to resolve the accreting region both spatially and spectroscopically, probing the true nature and physical state of the X-ray emitting plasma. Athena+ has the capabilities to permit a definitive understanding of the formation and evolution of large-scale cosmic structure through the study of the cluster population.