Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Velocity dispersions of dwarf spheroidal galaxies: dark matter versus
  MOND   We present predictions for the line-of-sight velocity dispersion profiles of
dwarf spheroidal galaxies and compare them to observations in the case of the
Fornax dwarf. The predictions are made in the framework of standard dynamical
theory of spherical systems with different velocity distributions. The stars
are assumed to be distributed according to Sersic laws with parameters fitted
to observations. We compare predictions obtained assuming the presence of dark
matter haloes (with density profiles adopted from N-body simulations) versus
those resulting from Modified Newtonian Dynamics (MOND). If the anisotropy of
velocity distribution is treated as a free parameter observational data for
Fornax are reproduced equally well by models with dark matter and with MOND. If
stellar mass-to-light ratio of $1 M_{\sun}/L_{\sun}$ is assumed, the required
mass of the dark halo is $1.5 \times 10^9 M_{\sun}$, two orders of magnitude
bigger than the mass in stars. The derived MOND acceleration scale is $a_0 =
2.1 \times 10^{-8}$ cm/s$^2$. In both cases a certain amount of tangential
anisotropy in the velocity distribution is needed to reproduce the shape of the
velocity dispersion profile in Fornax.

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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat