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Title: Systematic problems with using dark matter simulations to model stellar halos

The limits of available computing power have forced models for the structure of stellar halos to adopt one or both of the following simplifying assumptions: (1) stellar mass can be 'painted' onto dark matter (DM) particles in progenitor satellites; (2) pure DM simulations that do not form a luminous galaxy can be used. We estimate the magnitude of the systematic errors introduced by these assumptions using a controlled set of stellar halo models where we independently vary whether we look at star particles or painted DM particles, and whether we use a simulation in which a baryonic disk galaxy forms or a matching pure DM simulation that does not form a baryonic disk. We find that the 'painting' simplification reduces the halo concentration and internal structure, predominantly because painted DM particles have different kinematics from star particles even when both are buried deep in the potential well of the satellite. The simplification of using pure DM simulations reduces the concentration further, but increases the internal structure, and results in a more prolate stellar halo. These differences can be a factor of 1.5-7 in concentration (as measured by the half-mass radius) and 2-7 in internal density structure. Given this level ofmore » systematic uncertainty, one should be wary of overinterpreting differences between observations and the current generation of stellar halo models based on DM-only simulations when such differences are less than an order of magnitude.« less
Authors:
 [1] ; ;  [2] ;  [3] ;  [4] ; ;  [5]
  1. Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487-0324 (United States)
  2. Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States)
  3. Max-Planck-Institut für Astronomie (MPIA), Königstuhl 17, D-69117 Heidelberg (Germany)
  4. Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)
  5. Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4M1 (Canada)
Publication Date:
OSTI Identifier:
22351601
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 783; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CONCENTRATION RATIO; DENSITY; GALAXIES; MASS; NONLUMINOUS MATTER; SATELLITES; SIMULATION; STARS