Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The distribution and kinematics of early high-sigma peaks in present-day
  haloes: implications for rare objects and old stellar populations   We show that the hierarchical assembly of cold dark matter (CDM) haloes
preserves the memory of the initial conditions. Using N-body cosmological
simulations, we demonstrate that the present-day spatial distribution and
kinematics of objects that formed within early (z > 10) protogalactic systems
(old stars, satellite galaxies, globular clusters, massive black holes, etc.)
depends mostly on the rarity of the peak of the primordial density field which
they originally belonged to. Only for objects forming at lower redshifts the
exact formation site within the progenitor halo (e.g. whether near the center
or in an extended disk) becomes important. In present-day haloes, material from
the rarer early peaks is more centrally concentrated and falls off more steeply
with radius compared to the overall mass distribution, it has a lower velocity
dispersion, moves on more radial orbits, and has a more elongated shape.
Population II stars that formed within protogalactic haloes collapsing from
>2.5 sigma fluctuations would follow today a r^{-3.5} density profile with a
half-light radius of 17 kpc and a velocity anisotropy that increases from
isotropic in the inner regions to nearly radial at the halo edge. This agrees
well with the radial velocity dispersion profile of Galaxy halo stars from
Battaglia et al. (2005) and with the anisotropic orbits of nearby halo stars.

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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: alg-geom