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

Date

2005

Authors

Napolitano, Nicola R
Capaccioli, Massimo
Romanowsky, A J
Douglas, Nigel G
Merrifield, M R
Kuijken, Konrad
Arnaboldi, Magda
Gerhard, Ortwin
Freeman, Kenneth

Journal Title

Journal ISSN

Volume Title

Publisher

Blackwell Publishing Ltd

Abstract

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 ∈SF. 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 ∈SF > 1. This difficulty is eased if dark haloes are not assumed to have the standard ΛCDM profiles, but lower central concentrations.

Description

Keywords

Keywords: Dark matter; Galaxies: evolution; Galaxies: fundamental parameters; Galaxies: haloes; Galaxies: kinematics and dynamics

Citation

Source

Monthly Notices of the Royal Astronomical Society

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1111/j.1365-2966.2005.08683.x

Restricted until

2037-12-31