Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mass function and assembly of dark halos: an approach to inventory
  isolated overdense regions in random fields   In order to attain a statistical description of the evolution of cosmic
density fluctuations in agreement with results from the numerical simulations,
we introduce a probability conditional formalism (CF) based on an inventory of
isolated overdense regions in a density random field. This formalism is a
useful tool for describing at the same time the mass function (MF) of dark
haloes, their mass aggregation histories (MAHs) and merging rates (MRs). The CF
focuses on virialized regions in a self-consistent way rather than in mass
elements, and it offers an economical description for a variety of random
fields. Within the framework of the CF, we confirm that, for a Gaussian field,
it is not possible to reproduce at the same time the MF, MAH, and MR of haloes,
both for a constant and moving barrier. Then, we develop an inductive method
for constraining the cumulative conditional probability from a given halo MF
description, and thus, using the CF, we calculate the halo MAHs and MRs. By
applying this method to the MF measured in numerical simulations by Tinker et
al. 2008, we find that a reasonable solution, justified by a mass conservation
argument, is obtained if ones introduce a rescaling -increment by ~30% - of the
virial mass used in simulations and a (slight) deviation from Gaussianity.
Thus, both the MAH and MR obtained by a Monte Carlo merger tree agree now with
the predictions of numerical simulations. We discuss on the necessity of
rescaling the virial mass in simulations when comparing with analytical
approaches on the ground of the matter not accounted as part of the halos and
the halo mass limit due to numerical. Our analysis supports the presence of a
diffuse dark matter component that is not taken into account in the measured
halo MFs inasmuch as it is not part of the collapsed structures.

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The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: math-ph
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The categories of this paper are: eess