The progenitor galaxies of the intracluster light
Abstract
Intracluster Light (ICL) is a diffuse stellar component of galaxy groups and clusters, bound to the structure's potential rather than to individual galaxies and primarily formed through the stripping and mergers of intermediate-mass galaxies. Its formation and evolution is strongly linked to the central galaxies of groups and clusters, typically the Brightest Cluster Galaxies (BCGs) in clusters. To determine the properties of the progenitor galaxies of the ICL of clusters and groups at redshift z = 0 and compare them with the progenitors of their BCGs. We select 127 clusters and groups in the hydrodynamic Illustris-TNG100 simulation above a mass of 10^{13}~M⊙. We divide the ICL from the BCG by applying a surface brightness cut at the Holmberg radius of 26.5 mag/arcsec^{-2}, where star particles within this radius are defined as attached to the BCG, and outside, the ICL. We then determine the masses and contributions of progenitor galaxies of the ICL and BCG. We find that the number of ICL progenitors increases with structure mass, and that the ICL has more progenitors than the BCG. The ICL has a larger percentage of material from low-mass galaxies. Quenched galaxies contributed a large fraction of the ICL, and this fraction increases with galaxy mass. The mean mass radial gradient of ex-situ material in structures for the ICL and the BCG+ICL is generally negative and increases with structure mass, indicating that material from more massive progenitors is found towards the centres of clusters. The mean mass radial gradient is significantly impacted by structure formation history. ICL progenitor properties are impacted by structure history and are therefore highly individual to each system. At a given structure mass, there is diversity in the properties of the progenitors that formed the ICL. Although the BCG and the ICL co-evolve, the BCG has fewer, more massive progenitors.
Related
- A Consistent Comparison of Intracluster Light Assembly in Simulations I. Redshift Evolution and Progenitor Galaxies
- Intracluster light in the infall region of simulated protoclusters of galaxies
- How sky subtraction scales affect Intracluster light measurements
- Isophotal signatures of the brightest cluster galaxy - intracluster light transition
- Kinematically isolating intracluster light in AS1063: a distinct stellar population tracing the dark matter core
BibTeX
@misc{mayes2026progenitor,
title = {{The progenitor galaxies of the intracluster light}},
author = {Rebecca J. Mayes and Facundo A. Gómez and Antonela Monachesi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10785},
eprint = {2610.10785},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10785},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The progenitor galaxies of the intracluster light
AU - Rebecca J. Mayes
AU - Facundo A. Gómez
AU - Antonela Monachesi
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10785
UR - https://arxiv.org/abs/2610.10785
AB - Intracluster Light (ICL) is a diffuse stellar component of galaxy groups and clusters, bound to the structure's potential rather than to individual galaxies and primarily formed through the stripping and mergers of intermediate-mass galaxies. Its formation and evolution is strongly linked to the central galaxies of groups and clusters, typically the Brightest Cluster Galaxies (BCGs) in clusters. To determine the properties of the progenitor galaxies of the ICL of clusters and groups at redshift z = 0 and compare them with the progenitors of their BCGs. We select 127 clusters and groups in the hydrodynamic Illustris-TNG100 simulation above a mass of 10^{13}~M_⊙. We divide the ICL from the BCG by applying a surface brightness cut at the Holmberg radius of 26.5 mag/arcsec^{-2}, where star particles within this radius are defined as attached to the BCG, and outside, the ICL. We then determine the masses and contributions of progenitor galaxies of the ICL and BCG. We find that the number of ICL progenitors increases with structure mass, and that the ICL has more progenitors than the BCG. The ICL has a larger percentage of material from low-mass galaxies. Quenched galaxies contributed a large fraction of the ICL, and this fraction increases with galaxy mass. The mean mass radial gradient of ex-situ material in structures for the ICL and the BCG+ICL is generally negative and increases with structure mass, indicating that material from more massive progenitors is found towards the centres of clusters. The mean mass radial gradient is significantly impacted by structure formation history. ICL progenitor properties are impacted by structure history and are therefore highly individual to each system. At a given structure mass, there is diversity in the properties of the progenitors that formed the ICL. Although the BCG and the ICL co-evolve, the BCG has fewer, more massive progenitors.
ER -