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

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.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. © 2022. The Author(s). Published by the American Astronomical Society.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 (2006). 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.Peer reviewe

Ranking Theoretical Supernovae Explosion Models from Observations of the Intracluster Gas

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.The intracluster medium (ICM) is a reservoir of heavy elements synthesized by different supernovae (SNe) types over cosmic history. Different enrichment mechanisms contribute a different relative metal production, predominantly caused by different SNe type dominance. Using spatially resolved X-ray spectroscopy, one can probe the contribution of each metal-enrichment mechanism. However, a large variety of physically feasible supernova (SN) explosion models make the analysis of the ICM enrichment history more uncertain. This paper presents a nonparametric probability distribution function analysis to rank different theoretical SNe yields models by comparing their performance against observations. Specifically, we apply this new methodology to rank 7192 combinations of core-collapse SN and Type Ia SN models using eight abundance ratios from Suzaku observations of 18 galaxy systems (clusters and groups) to test their predictions. This novel technique can compare many SN models and maximize spectral information extraction, considering all the individual measurable abundance ratios and their uncertainties. We find that Type II SNe with nonzero initial metallicity progenitors in general performed better than pair-instability SN and hypernova models, and that 3D SNIa models (with a white dwarf progenitor central density of 2.9 × 109 g cm−3) performed best among all tested SN model pairs. © 2022. The Author(s). Published by the American Astronomical Society.This work uses archived Suzaku satellite observations. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES) – Finance Code 001. R.A.D. acknowledges partial support from NASA grant Nos. 80NSSC20P0540 and 80NSSC20P0597 and a CNPq grant No. 308105/2018-4. Y. J-T has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-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 Astrofísica de Andalucía (SEV-2017-0709). We thank Dr. Francois Mernier for kindly suggesting the Heidelberg Supernova Model Archive (HESMA), https://hesma.h-its.org, which this work made use of. This research has made use of NASA/IPAC Extragalactic Database, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. This work made use of the cosmological calculator from Wright (2006).Peer reviewe