J-PLUS: analysis of the intracluster light in the Coma cluster

TL;DR

This study measures the intracluster light (ICL) in the Coma cluster across multiple wavelengths using a new technique, revealing insights into the cluster's merging activity and the nature of its diffuse stellar component.

Contribution

It introduces the Chebyshev-Fourier Intracluster Light Estimator (CICLE) for robust ICL measurement across multiple filters, providing new insights into the ICL's properties and formation mechanisms in a merging cluster.

Findings

ICL fraction varies from 7% to 21% across filters

Higher ICL fractions observed in narrowband filters J0395, J0410, J0430

ICL shows a bluer stellar population indicating recent or ongoing mergers

Abstract

The intracluster light (ICL) is a luminous component of galaxy clusters composed of stars that are gravitationally bound to the cluster potential but do not belong to the individual galaxies. Previous studies of the ICL have shown that its formation and evolution are intimately linked to the evolutionary stage of the cluster. Thus, the analysis of the ICL in the Coma cluster will give insights into the main processes driving the dynamics in this highly complex system. Using a recently developed technique, we measure the ICL fraction in Coma at several wavelengths, using the J-PLUS unique filter system. The combination of narrow- and broadband filters provides valuable information on the dynamical state of the cluster, the ICL stellar types, and the morphology of the diffuse light. We use the Chebyshev-Fourier Intracluster Light Estimator (CICLE) to disentangle the ICL from the light of the galaxies, and to robustly measure the ICL fraction in seven J-PLUS filters. We obtain the ICL fraction distribution of the Coma cluster at different optical wavelengths, which varies from $\sim 7\%-21\%$, showing the highest values in the narrowband filters J0395, J0410, and J0430. This ICL fraction excess is distinctive pattern recently observed in dynamically active clusters (mergers), indicating a higher amount of bluer stars in the ICL compared to the cluster galaxies. Both the high ICL fractions and the excess in the bluer filters are indicative of a merging state. The presence of younger/lower-metallicity stars the ICL suggests that the main mechanism of ICL formation for the Coma cluster is the stripping of the stars in the outskirts of infalling galaxies and, possibly, the disruption of dwarf galaxies during past/ongoing mergers.