Abstract
We present new spectroscopic observations of the gravitational arcs and the brightest cluster galaxy (BCG) in the cluster MS 2137-23 (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, ρd ∝ r-β, with β < 0.9 at a 99% CL. Steep inner slopes obtained in cold dark matter cosmological simulations - such as Navarro, Frenk, & White (β = 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 provide a powerful test of the cold dark matter paradigm at the cluster mass scale.
Original language | English (US) |
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Pages (from-to) | L129-L133 |
Journal | Astrophysical Journal |
Volume | 574 |
Issue number | 2 II |
DOIs | |
State | Published - Aug 1 2002 |
Externally published | Yes |
Keywords
- Galaxies: elliptical and lenticular, cD
- Galaxies: evolution
- Galaxies: formation
- Galaxies: structure
- Gravitational lensing
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science