Unveiling the Dynamical State of Massive Clusters through the ICL Fraction

Yolanda Jiménez-Teja, Renato Dupke, Narciso Benítez, Anton M. Koekemoer, Adi Zitrin, Keiichi Umetsu, Bodo L. Ziegler, Brenda L. Frye, Holland Ford, Rychard J. Bouwens, Larry D. Bradley, Thomas Broadhurst, Dan Coe, Megan Donahue, Genevieve J. Graves, Claudio Grillo, Leopoldo Infante, Stephanie Jouvel, Daniel D. Kelson, Ofer LahavRuth Lazkoz, Dorom Lemze, Dan Maoz, Elinor Medezinski, Peter Melchior, Massimo Meneghetti, Amata Mercurio, Julian Merten, Alberto Molino, Leonidas A. Moustakas, Mario Nonino, Sara Ogaz, Adam G. Riess, Piero Rosati, Jack Sayers, Stella Seitz, Wei Zheng

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


We have selected a sample of 11 massive clusters of galaxies observed by the Hubble Space Telescope in order to study the impact of the dynamical state on the intracluster light (ICL) fraction, the ratio of total integrated ICL to the total galaxy member light. With the exception of the Bullet cluster, the sample is drawn from the Cluster Lensing and Supernova Survey and the Frontier Fields program, containing five relaxed and six merging clusters. The ICL fraction is calculated in three optical filters using the CHEFs ICL estimator, a robust and accurate algorithm free of a priori assumptions. We find that the ICL fraction in the three bands is, on average, higher for the merging clusters, ranging between ∼7% and 23%, compared with the ∼2%-11% found for the relaxed systems. We observe a nearly constant value (within the error bars) in the ICL fraction of the regular clusters at the three wavelengths considered, which would indicate that the colors of the ICL and the cluster galaxies are, on average, coincident and, thus, so are their stellar populations. However, we find a higher ICL fraction in the F606W filter for the merging clusters, consistent with an excess of lower-metallicity/younger stars in the ICL, which could have migrated violently from the outskirts of the infalling galaxies during the merger event.

Original languageEnglish
Article number79
JournalAstrophysical Journal
Issue number2
StatePublished - 20 Apr 2018


  • galaxies: clusters: general
  • techniques: image processing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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