Modelling the Formation of Individual Galaxies: A Morphology Problem for CDM?

Abstract

We use a semi-analytic model of halo formation to study the dynamical history of giant field galaxies like the Milky Way. We find that in a concordance LCDM cosmology, most isolated disk galaxies have remained undisturbed for 8-10 Gyr, such that the age of the Milky Way's thin disk is unremarkable. Many systems also have older disk components which have been thickened by minor mergers, consistent with recent observations of nearby field galaxies. We do have a considerable problem, however, reproducing the morphological mix of nearby galaxies. In our fiducial model, most systems have disk-to-bulge mass ratios of order 1, and look like S0s rather than spirals. This result depends mainly on merger statistics, and is unchanged for most reasonable choices of our model parameters. We discuss two possible solutions to this morphology problem in LCDM.

4 pages, 8 figures, to appear in "The Evolution of Galaxies III: From Simple Approaches to Self-Consistent Models", proceedings of the 3rd EuroConference on the evolution of galaxies, held in Kiel, Germany, July 16-20, 2002

References in corpus (3)

• The Dynamics of Sinking Satellites Around Disk Galaxies: A Poor Man's Alternative to High-Resolution Numerical Simulations
• A Structural and Dynamical Study of Late-Type, Edge-On Galaxies: II. Vertical Color Gradients and the Detection of Ubiquitous Thick Disks
• Physical Implications of the X-ray Properties of Galaxy Groups and Clusters

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• A Catalog of Edge-on Disk Galaxies: From Galaxies with a Bulge to Superthin Galaxies
• Massive black hole remnants of the first stars I: abundance in present-day galactic haloes
• Photometric Properties of Six Local Volume Dwarf Galaxies from Deep Near-Infrared Observations