THE DARK MATTER DISTRIBUTION IN A383: EVIDENCE FOR A SHALLOW DENSITY CUSP FROM IMPROVED LENSING, STELLAR KINEMATIC, AND X-RAY DATA

Journal Article · Sun Feb 20 04:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/728/2/L39· OSTI ID:21560480

Newman, Andrew B; Ellis, Richard S ^[1]; Treu, Tommaso; Sand, David J ^[2]

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1. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States)
2. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

We extend our analyses of the dark matter (DM) distribution in relaxed clusters to the case of A383, a luminous X-ray cluster at z = 0.189 with a dominant central galaxy and numerous strongly lensed features. Following our earlier papers, we combine strong and weak lensing constraints secured with Hubble Space Telescope and Subaru imaging with the radial profile of the stellar velocity dispersion of the central galaxy, essential for separating the baryonic mass distribution in the cluster core. Hydrostatic mass estimates from Chandra X-ray observations further constrain the solution. These combined data sets provide nearly continuous constraints extending from 2 kpc to 1.5 Mpc in radius, allowing stringent tests of results from recent numerical simulations. Two key improvements in our data and its analysis make this the most robust case yet for a shallow slope {beta} of the DM density profile {rho}{sub DM} {proportional_to} r {sup -}{beta} on small scales. First, following deep Keck spectroscopy, we have secured the stellar velocity dispersion profile to a radius of 26 kpc for the first time in a lensing cluster. Second, we improve our previous analysis by adopting a triaxial DM distribution and axisymmetric dynamical models. We demonstrate that in this remarkably well-constrained system, the logarithmic slope of the DM density at small radii is {beta} < 1.0 (95% confidence). An improved treatment of baryonic physics is necessary, but possibly insufficient, to reconcile our observations with the recent results of high-resolution simulations.

• OSTI ID: 21560480
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 728; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BARYONS
COMPUTERIZED SIMULATION
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
CUSPED GEOMETRIES
DENSITY
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
GALAXIES
GALAXY CLUSTERS
HADRONS
IONIZING RADIATIONS
MAGNETIC FIELD CONFIGURATIONS
MASS DISTRIBUTION
MATTER
NONLUMINOUS MATTER
OPEN CONFIGURATIONS
PHYSICAL PROPERTIES
RADIATIONS
SIMULATION
SPATIAL DISTRIBUTION
X RADIATION
X-RAY GALAXIES