Independent Evidence for Earlier Formation Epochs of Fossil Groups of Galaxies through the Intracluster Light: The Case for RX J100742.53+380046.6

Renato A. Dupke, Yolanda Jimenez-Teja, Yuanyuan Su, Eleazar R. Carrasco, Anton M. Koekemoer, Rebeca M. Batalha, Lucas Johnson, Jimmy Irwin, Eric MIller, Paola Dimauro, Nícolas O.L. de Oliveira, Jose Vilchez

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Fossil groups (FG) of galaxies still present a puzzle to theories of structure formation. Despite the low number of bright galaxies, they have relatively high velocity dispersions and ICM temperatures often corresponding to cluster-like potential wells. Their measured concentrations are typically high, indicating early formation epochs as expected from the originally proposed scenario for their origin as being older undisturbed systems. This is, however, in contradiction with the typical lack of expected well developed cool cores. Here, we apply a cluster dynamical indicator recently discovered in the intracluster light fraction (ICLf) to a classic FG, RX J1000742.53+380046.6, to assess its dynamical state. We also refine that indicator to use as an independent age estimator. We find negative radial temperature and metal abundance gradients, the abundance achieving supersolar values at the hot core. The X-ray flux concentration is consistent with that of cool core systems. The ICLf analysis provides an independent probe of the system’s dynamical state and shows that the system is very relaxed, more than all clusters, where the same analysis has been performed. The specific ICLf is about 6 times higher, than any of the clusters previously analyzed, which is consistent with an older noninteractive galaxy system that had its last merging event within the last ∼5 Gyr. The specific ICLf is predicted to be an important new tool to identify fossil systems and to constrain the relative age of clusters.

Original languageEnglish
Article number59
JournalAstrophysical Journal
Volume936
Issue number1
DOIs
StatePublished - Sep 1 2022

Bibliographical note

Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.

Funding

R.A.D. acknowledges partial support from NASA grants 80NSSC20P0540 and 80NSSC20P0597 and the CNPq grant 308105/2018-4. R.A.D. also thanks Drs. MARc Kessler for very insightful discussions, Francois Mernier and Zack Li for helpful suggestions. This paper used the cosmology calculator of Wright (). Y.J.-T. has received funding from the European Unions Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 898633. Y.J.-T. also acknowledges financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award to the Instituto de Astrofsica de Andaluca (SEV-2017-0709). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001. Based on observations obtained at the international Gemini Observatory, a program of NSFs NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This work was enabled by observations made from the Gemini North telescope, located within the Maunakea Science Reserve and adjacent to the summit of Maunakea. We are grateful for the privilege of observing the universe from a place that is unique in both its astronomical quality and its cultural significance.

FundersFunder number
NSFs NOIRLab
State Agency for Research
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China
National Aeronautics and Space Administration80NSSC20P0540, 80NSSC20P0597
National Aeronautics and Space Administration
Horizon 2020 Framework Programme
H2020 Marie Skłodowska-Curie Actions898633
H2020 Marie Skłodowska-Curie Actions
National Research Council Canada (NRCC)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Ministerio de Ciencia, Tecnología e Innovación Productiva
Conselho Nacional de Desenvolvimento Científico e Tecnológico308105/2018-4
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Korea Astronomy and Space Science Institute
Horizon 2020
Ministério da Ciência, Tecnologia, Inovações e Comunicações
Instituto de Astrofísica de AndalucíaSEV-2017-0709
Instituto de Astrofísica de Andalucía
Agencia Nacional de Investigación y Desarrollo

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

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