Characterising the intra-cluster light in The Three Hundred simulations

¹ Departamento de Física Teórica, Módulo 15, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
e-mail: ana.contreras@uam.es
² Centro de Investigación Avanzada en Física Fundamental (CIAFF), Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
³ International Centre for Radio Astronomy Research, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
⁴ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁵ Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
⁶ Departamento de Astrofísica, Universidad de La Laguna, Av. Astrofísico Francisco Sanchez s/n, 38206 La Laguna, Tenerife, Spain
⁷ Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
⁸ Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
⁹ Centre for Astrophysics & Supercomputing, Swinburne University of Technology, 1 Alfred St, Hawthorn, VIC 3122, Australia
¹⁰ ARC Centre of Excellence for Dark Matter Particle Physics (CDM), Melbourne, Australia
¹¹ School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
¹² INAF – Osservatorio Astronomico di Trieste, Via Tiepolo 11, I34131 Trieste, Italy
¹³ IFPU – Institute for Fundamental Physics of the Universe, Via Beirut 2, 34151 Trieste, Italy

Received: 2 November 2023
Accepted: 12 December 2023

Abstract

We characterise the intra-cluster light (ICL) in ensembles of full-physics cluster simulations from THE THREE HUNDRED project, a suite of 324 hydrodynamical resimulations of cluster-sized halos. We identify the ICL as those stellar particles bound to the potential of the cluster itself, but not to any of its substructures, and separate the brightest cluster galaxy (BCG) by means of a fixed 50 kpc aperture. We find the total BCG+ICL mass to be in agreement with state-of-the-art observations of galaxy clusters. The ICL mass fraction of our clusters is between 30 and 50% of the total stellar mass within R₅₀₀, while the BCG represents around 10%. We further find no trend of the ICL fraction with cluster halo mass, at least not in the range [0.2, 3] 10¹⁵ h⁻¹ M_⊙ considered here. For the dynamical state, characterised both by theoretical estimators and by the recent merging history of the cluster, there is a clear correlation, such that more relaxed clusters and those that have undergone fewer recent mergers have a higher ICL fraction. Finally, we investigate the possibility of using the ICL to explore the dark matter (DM) component of galaxy clusters. We compute the volumetric density profile for the DM and ICL components and show that, up to R₅₀₀, the ratio between the two can be described by a power law. Working with the velocity dispersion profiles instead, we show that the ratio can be fit by a straight line. Providing the parameters of these fits, we show how the ICL can be used to infer DM properties.