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Mass-to-light ratio gradients in early-type galaxy haloes

Napolitano, N. R. ; Capaccioli, M. ; Romanowsky, A. J. ; Douglas, N. G. ; Merrifield, M. R. ; Kuijken, K. ; Arnaboldi, M. ; Gerhard, O. ; Freeman, K. C.

In: Monthly Notices of the Royal Astronomical Society, 2005, vol. 357, no. 2, p. 691-706

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    Titel
    • Mass-to-light ratio gradients in early-type galaxy haloes
    Autor
    • Napolitano, N. R.. Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, the Netherlands
    • Capaccioli, M.. INAF-Astronomical Observatory of Capodimonte, via Moiariello 16, I-80131 Naples, Italy
    • Romanowsky, A. J.. Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
    • Douglas, N. G.. Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, the Netherlands
    • Merrifield, M. R.. School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD
    • Kuijken, K.. Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, the Netherlands
    • Arnaboldi, M.. INAF-Astronomical Observatory of Pino Torinese, via Osservatorio 20, I-10025 Pino Torinese, Italy
    • Gerhard, O.. Astronomy department, University of Basel, Venusstrasse, Basel, Switzerland
    • Freeman, K. C.. RSAA, Mt. Stromlo Observatory, Weston Creek P.O., ACT 2611, Australia
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Monthly Notices of the Royal Astronomical Society, 2005, vol. 357, no. 2, p. 691-706. Blackwell Science Ltd
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:304286
    Summary
    Owing to the fact that the near future should see a rapidly expanding set of probes of the halo masses of individual early-type galaxies, we introduce a convenient parameter for characterizing the halo masses from both observational and theoretical results: ∇ℓϒ, the logarithmic radial gradient of the mass-to-light ratio. Using halo density profiles from Λ-cold dark matter (CDM) simulations, we derive predictions for this gradient for various galaxy luminosities and star formation efficiencies εSF. As a pilot study, we assemble the available ∇ℓϒ data from kinematics in early-type galaxies - representing the first unbiased study of halo masses in a wide range of early-type galaxy luminosities - and find a correlation between luminosity and ∇ℓϒ, such that the brightest galaxies appear the most dark-matter dominated. We find that the gradients in most of the brightest galaxies may fit in well with the ΛCDM predictions, but that there is also a population of fainter galaxies whose gradients are so low as to imply an unreasonably high star formation efficiency εSF > 1. This difficulty is eased if dark haloes are not assumed to have the standard ΛCDM profiles, but lower central concentrations