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The Density Profiles of Massive, Relaxed Galaxy Clusters. II. Separating Luminous and Dark Matter in Cluster Cores

Newman, Andrew B. and Treu, Tommaso and Ellis, Richard S. and Sand, David J. (2013) The Density Profiles of Massive, Relaxed Galaxy Clusters. II. Separating Luminous and Dark Matter in Cluster Cores. Astrophysical Journal, 765 (1). Art. No. 25. ISSN 0004-637X. doi:10.1088/0004-637X/765/1/25.

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We present stellar and dark matter (DM) density profiles for a sample of seven massive, relaxed galaxy clusters derived from strong and weak gravitational lensing and resolved stellar kinematic observations within the centrally located brightest cluster galaxies (BCGs). In Paper I of the series, we demonstrated that the total density profile derived from these data, which span three decades in radius, is consistent with numerical DM-only simulations at radii ≳5-10 kpc, despite the significant contribution of stellar material in the core. Here, we decompose the inner mass profiles of these clusters into stellar and dark components. Parameterizing the DM density profile as a power law ρ_(DM) ∝ r^(–β) on small scales, we find a mean slope (β) = 0.50 ± 0.10(random)^(+0.14)_(–0.13)(systematic). Alternatively, cored Navarro-Frenk-White (NFW) profiles with (log r_(core)/kpc) = 1.14 ± 0.13^(+0.14)_(–0.22) provide an equally good description. These density profiles are significantly shallower than canonical NFW models at radii ≾30 kpc, comparable to the effective radii of the BCGs. The inner DM profile is correlated with the distribution of stars in the BCG, suggesting a connection between the inner halo and the assembly of stars in the central galaxy. The stellar mass-to-light ratio inferred from lensing and stellar dynamics is consistent with that inferred using stellar population synthesis models if a Salpeter initial mass function is adopted. We compare these results to theories describing the interaction between baryons and DM in cluster cores, including adiabatic contraction models and the possible effects of galaxy mergers and active galactic nucleus feedback, and evaluate possible signatures of alternative DM candidates.

Item Type:Article
Related URLs:
URLURL TypeDescription
Newman, Andrew B.0000-0001-7769-8660
Treu, Tommaso0000-0002-8460-0390
Ellis, Richard S.0000-0001-7782-7071
Sand, David J.0000-0003-4102-380X
Additional Information:© 2013 American Astronomical Society. Received 2012 September 21; accepted 2012 December 21; published 2013 February 13. It is a pleasure to acknowledge helpful conversations with Annika Peter. We thank Liang Gao for providing the Phoenix simulation results. The anonymous referee is thanked for a helpful report. R.S.E. acknowledges financial support from DOE grant DE-SC0001101. Research support by the Packard Foundation is gratefully acknowledged by T.T. The authors recognize and acknowledge the cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0001101
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:dark matter; galaxies: elliptical and lenticular, cD; gravitational lensing: strong; gravitational lensing: weak; stars: kinematics and dynamics
Issue or Number:1
Record Number:CaltechAUTHORS:20130402-095218716
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Official Citation:The Density Profiles of Massive, Relaxed Galaxy Clusters. II. Separating Luminous and Dark Matter in Cluster Cores Andrew B. Newman et al. 2013 ApJ 765 25
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37714
Deposited By: Ruth Sustaita
Deposited On:02 Apr 2013 17:11
Last Modified:09 Nov 2021 23:30

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