Rhapsody-G simulations I: the cool cores, hot gas and stellar content of massive galaxy clusters

TL;DR

This paper introduces the Rhapsody-G suite of cosmological hydrodynamic simulations of massive galaxy clusters, analyzing their cool-core properties, hot gas, and stellar content, and comparing results with observations.

Contribution

The study presents a comprehensive set of simulations capturing diverse cluster assembly histories, highlighting successes and limitations in reproducing observed cluster properties.

Findings

Simulations naturally produce a cool-core/non-cool core dichotomy.

Cool-core clusters have lower central entropy than observed, unaffected by thermal AGN feedback.

Simulated scaling relations agree with Planck SZ data but show deviations in X-ray luminosity and temperature.

Abstract

We present the Rhapsody-G suite of cosmological hydrodynamic AMR zoom simulations of ten massive galaxy clusters at the $M_{\rm vir}\sim10^{15}\,{\rm M}_\odot$ scale. These simulations include cooling and sub-resolution models for star formation and stellar and supermassive black hole feedback. The sample is selected to capture the whole gamut of assembly histories that produce clusters of similar final mass. We present an overview of the successes and shortcomings of such simulations in reproducing both the stellar properties of galaxies as well as properties of the hot plasma in clusters. In our simulations, a long-lived cool-core/non-cool core dichotomy arises naturally, and the emergence of non-cool cores is related to low angular momentum major mergers. Nevertheless, the cool-core clusters exhibit a low central entropy compared to observations, which cannot be alleviated by thermal AGN feedback. For cluster scaling relations we find that the simulations match well the $M_{500}-Y_{500}$ scaling of Planck SZ clusters but deviate somewhat from the observed X-ray luminosity and temperature scaling relations in the sense of being slightly too bright and too cool at fixed mass, respectively. Stars are produced at an efficiency consistent with abundance matching constraints and central galaxies have star formation rates consistent with recent observations. While our simulations thus match various key properties remarkably well, we conclude that the shortcomings strongly suggest an important role for non-thermal processes (through feedback or otherwise) or thermal conduction in shaping the intra-cluster medium.