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Cold Dark Matter Substructure and Galactic Disks

Published online by Cambridge University Press:  01 June 2008

Stelios Kazantzidis
Affiliation:
Center for Cosmology and Astro-Particle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA email: stelios@mps.ohio-state.edu
Andrew R. Zentner
Affiliation:
Department of Physics & Astronomy, University of Pittsburgh, 100 Allen Hall, 3941 O'Hara Street, Pittsburgh, PA 15260, USA email: zentner@pitt.edu
James S. Bullock
Affiliation:
Center for Cosmology, Department of Physics & Astronomy, The University of California at Irvine, 4168 Reines Hall, Irvine, CA 92697, USA email: bullock@uci.edu
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Abstract

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We perform a set of high-resolution, fully self-consistent dissipationless N-body simulations to investigate the influence of cold dark matter (CDM) substructure on the dynamical evolution of thin galactic disks. Our method combines cosmological simulations of galaxy-sized CDM halos to derive the properties of substructure populations and controlled numerical experiments of consecutive subhalo impacts onto initially-thin, fully-formed disk galaxies. We demonstrate that close encounters between massive subhalos and galactic disks since z ~ 1 should be common occurrences in ΛCDM models. In contrast, extremely few satellites in present-day CDM halos are likely to have a significant impact on the disk structure. One typical host halo merger history is used to seed controlled N-body experiments of subhalo-disk encounters. As a result of these accretion events, the disk thickens considerably at all radii with the disk scale height increasing in excess of a factor of 2 in the solar neighborhood. We show that interactions with the subhalo population produce a wealth of distinctive morphological signatures in the disk stars, many of which resemble those being discovered in the Milky Way (MW), M31, and in other disk galaxies, including: conspicuous flares; bars; low-lived, ring-like features in the outskirts; and low-density, filamentary structures above the disk plane. These findings highlight the significant role of CDM substructure in setting the structure of disk galaxies and driving galaxy evolution.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2009

References

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