Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The dark matter density profile of the lensing cluster MS2137-23: a test
  of the cold dark matter paradigm   We present new spectroscopic observations of the gravitational arcs and the
brightest cluster galaxy (BCG) in the cluster MS2137-23 (z=0.313) obtained with
the Echelle Spectrograph and Imager on the Keck II telescope. We find that the
tangential and radial arcs arise from sources at almost identical redshifts
(z=1.501,1.502). We combine the measured stellar velocity dispersion profile of
the BCG with a lensing analysis to constrain the distribution of dark and
stellar matter in the central 100 kpc of the cluster. Our data indicate a
remarkably flat inner slope for the dark matter profile, rho_d propto r^-beta,
with beta<0.9 at 99% CL. Steep inner slopes obtained in cold dark matter
cosmological simulations -- such as Navarro Frenk & White (beta=1) or Moore
(1.5) universal dark matter profiles -- are ruled out at better than 99% CL. As
baryon collapse is likely to have steepened the dark matter profile from its
original form, our data provides a powerful test of the cold dark matter
paradigm at the cluster mass scale.

9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
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The categories of this paper are: econ
29
The categories of this paper are: funct-an