Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The dark matter halos of spheroidal galaxies and clusters of galaxies   We describe the first results from two observational projects aimed at
measuring the amount and spatial distribution of dark matter in distant
early-type galaxies (E/S0s) and clusters of galaxies. At the galaxy scale, the
Lenses Structure and Dynamics (LSD) Survey is gathering kinematic data for
distant (up to $z\sim1$) E/S0s that are gravitational lenses. A joint lensing
and dynamical analysis constrains the fraction of dark matter within the
Einstein radius, the mass-to-light ratio of the stellar component, and the
total slope of the mass density profile. These properties and their evolution
with redshift are briefly discussed in terms of the formation and evolution of
E/S0 galaxies and measurement of the Hubble Constant from gravitational time
delay systems. At the cluster scale -- after careful removal of the stellar
component with a joint lensing and dynamical analysis -- systems with giant
radial arcs can be used to measure precisely the inner slope of the dark matter
halo. An HST search for radial arcs and the analysis of a first sample are
briefly discussed in terms of the universal dark matter halos predicted by CDM
simulations.

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The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
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The categories of this paper are: econ
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex