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Title: Understanding the unique assembly history of central group galaxies

Central galaxies (CGs) in massive halos live in unique environments with formation histories closely linked to that of the host halo. In local clusters, they have larger sizes (R{sub e} ) and lower velocity dispersions (σ) at fixed stellar mass M {sub *}, and much larger R{sub e} at a fixed σ than field and satellite galaxies (non-CGs). Using spectroscopic observations of group galaxies selected from the COSMOS survey, we compare the dynamical scaling relations of early-type CGs and non-CGs at z ∼ 0.6 to distinguish possible mechanisms that produce the required evolution. CGs are systematically offset toward larger R{sub e} at fixed σ compared to non-CGs with similar M {sub *}. The CG R{sub e} -M {sub *} relation also shows differences, primarily driven by a subpopulation (∼15%) of galaxies with large R{sub e} , while the M {sub *}-σ relations are indistinguishable. These results are accentuated when double Sérsic profiles, which better fit light in the outer regions of galaxies, are adopted. They suggest that even group-scale CGs can develop extended components by these redshifts that can increase total R{sub e} and M {sub *} estimates by factors of ∼2. To probe the evolutionary link between our samplemore » and cluster CGs, we also analyze two cluster samples at z ∼ 0.6 and z ∼ 0. We find similar results for the more massive halos at comparable z, but much more distinct CG scaling relations at low-z. Thus, the rapid, late-time accretion of outer components, perhaps via the stripping and accretion of satellites, would appear to be a key feature that distinguishes the evolutionary history of CGs.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwa 277-8582 (Japan)
  2. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
  3. GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 61 Avenue de I'Observatoire, 75014, Paris (France)
  4. European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching bei Muenchen (Germany)
  5. Laboratoire d'Astrophysique, Ecole Polytechnique Fédérale de Lausanne, Observatoire de Sauverny, CH-1290 Versoix (Switzerland)
  6. Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  7. Department of Physics and Astronomy, Bologna University, viale Berti-Pichat 6/2, I-40127 Bologna (Italy)
Publication Date:
OSTI Identifier:
22370065
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 797; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; DISPERSIONS; GALAXIES; GALAXY CLUSTERS; GALAXY NUCLEI; MASS; RED SHIFT; SATELLITES; STAR EVOLUTION; STRIPPING; UNIVERSE; VELOCITY; VISIBLE RADIATION