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Title: Dark-matter halo assembly bias: Environmental dependence in the non-Markovian excursion-set theory

In the standard excursion-set model for the growth of structure, the statistical properties of halos are governed by the halo mass and are independent of the larger-scale environment in which the halos reside. Numerical simulations, however, have found the spatial distributions of halos to depend not only on their mass but also on the details of their assembly history and environment. Here we present a theoretical framework for incorporating this 'assembly bias' into the excursion-set model. Our derivations are based on modifications of the path-integral approach of Maggiore and Riotto that models halo formation as a non-Markovian random-walk process. The perturbed density field is assumed to evolve stochastically with the smoothing scale and exhibits correlated walks in the presence of a density barrier. We write down conditional probabilities for multiple barrier crossings and derive from them analytic expressions for descendant and progenitor halo mass functions and halo merger rates as a function of both halo mass and the linear overdensity δ {sub e} of the larger-scale environment of the halo. Our results predict a higher halo merger rate and higher progenitor halo mass function in regions of higher overdensity, consistent with the behavior seen in N-body simulations.
Authors:
 [1] ;  [2] ;  [3]
  1. Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, 955 Jianchuan road, Shanghai 200240 (China)
  2. Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
  3. Department of Theoretical Physics and Center for Astroparticle Physics (CAP), 24 quai E. Ansermet, 1211-CH Geneva (Switzerland)
Publication Date:
OSTI Identifier:
22348036
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DENSITY; DIFFUSION BARRIERS; EXCURSIONS; GALAXY CLUSTERS; GRAPH THEORY; MARKOV PROCESS; MASS; MODIFICATIONS; NONLUMINOUS MATTER; SET THEORY; SPATIAL DISTRIBUTION