Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fossils of Reionization in the Local Group   We use a combination of high-resolution gasdynamics simulations of
high-redshift dwarf galaxies and dissipationless simulations of a Milky Way
sized halo to estimate the expected abundance and spatial distribution of the
dwarf satellite galaxies that formed most of their stars around z~8 and evolved
only little since then. Such galaxies can be considered as fossils of the
reionization era, and studying their properties could provide a direct window
into the early, pre-reionization stages of galaxy formation. We show that 5-15%
of the objects existing at z~8 do indeed survive until the present in the MW
like environment without significant evolution. This implies that it is
plausible that the fossil dwarf galaxies do exist in the Local Group. Because
such galaxies form their stellar systems early during the period of active
merging and accretion, they should have spheroidal morphology regardless of
their current distance from the host galaxy. We show that both the expected
luminosity function and spatial distribution of dark matter halos which are
likely to host fossil galaxies agree reasonably well with the observed
distributions of the luminous (L_V>10^6 Lsun) Local Group fossil candidates
near the host galaxy (d<200 kpc). However, the predicted abundance is
substantially larger (by a factor of 2-3) for fainter galaxies (L_V<10^6 Lsun)
at larger distances (d>300 kpc). We discuss several possible explanations for
this discrepancy.

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The categories of this paper are: q-fin
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The categories of this paper are: econ
31
The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an