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Title page for ETD etd-03202015-141810

Type of Document Dissertation
Author Sissom, Daniel Jason
Author's Email Address daniel.j.sissom@vanderbilt.edu
URN etd-03202015-141810
Title Early Growth in a Perturbed Universe: Exploring Dark Matter Halo Populations in 2LPT and ZA Simulations
Degree PhD
Department Physics
Advisory Committee
Advisor Name Title
J. Kelly Holley-Bockelmann Committee Chair
Andreas A. Berlind Committee Member
David A. Weintraub Committee Member
Robert J. Scherrer Committee Member
Shane M. Hutson Committee Member
  • astronomy
  • cosmology
  • early universe
  • high redshift
  • dark matter
  • dark matter halos
  • galaxies
  • numerical methods
  • nbody simulations
  • simulation initialization
  • za
  • 2lpt
  • theoretical astrophysics
  • computational astrophysics
  • halo mass
  • halo concentration
Date of Defense 2015-03-17
Availability unrestricted
We study the structure and evolution of dark matter halos from z = 300 to z = 6 for two cosmological N-body simulation initialization techniques. While the second-order Lagrangian perturbation theory (2LPT) and the Zel'dovich approximation (ZA) both produce accurate present day halo mass functions, earlier collapse of dense regions in 2LPT can result in larger mass halos at high redshift. We explore the differences in dark matter halo mass and concentration due to initialization method through three 2LPT and three ZA initialized cosmological simulations. We find that 2LPT induces more rapid halo growth, resulting in more massive halos compared to ZA. This effect is most pronounced for high mass halos and at high redshift. Halo concentration is, on average, largely similar between 2LPT and ZA, but retains differences when viewed as a function of halo mass. For both mass and concentration, the difference between typical individual halos can be very large, highlighting the shortcomings of ZA-initialized simulations for high-z halo population studies.
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