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Concentrating the dark matter in galaxy clusters through tidal stripping of baryonically compressed galactic halos

Barkana, Rennan and Loeb, Abraham (2010) Concentrating the dark matter in galaxy clusters through tidal stripping of baryonically compressed galactic halos. Monthly Notices of the Royal Astronomical Society, 405 (3). pp. 1969-1975. ISSN 0035-8711.

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Gravitational lensing observations of massive X-ray clusters imply a steep characteristic density profile marked by a central concentration of dark matter. The observed mass fraction within a projected radius of 150 kpc is twice that found in state-of-the-art dark matter simulations of the standard Λ cold dark matter cosmology. A central baryon enhancement that could explain this discrepancy is not observed, leaving a major puzzle. We propose a solution based on the merger histories of clusters. A significant fraction of the final dark matter content of a cluster halo originates within galaxy-sized haloes, in which gas can cool and compress the dark matter core to high densities. The subsequent tidal stripping of this compressed dark matter occurs in denser regions that are closer to the centre of the cluster halo. Eventually, the originally cooled gas must be dispersed into the intracluster medium through feedback, for consistency with observations that do not find central baryon enhancements in clusters. Still, the early adiabatic compression of the galactic dark matter leaves a net effect on the cluster. Using a simple model for this process, we show that the central cluster profile is substantially modified, potentially explaining the observed discrepancy.

Item Type:Article
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Loeb, Abraham0000-0003-4330-287X
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 February 24. Received 2010 February 23; in original form 2009 July 6. RB is grateful for the kind hospitality of the Institute for Theory and Computation (ITC) at the Harvard–Smithsonian CfA, and also acknowledges support by the Moore Distinguished Scholar programme at Caltech and the John Simon Guggenheim Memorial Foundation. This work was supported in part by NASA grant NNX08AL43G, by Harvard University funds and by BSF grant 2004386.
Funding AgencyGrant Number
Caltech Moore Distinguished Scholar programmeUNSPECIFIED
John Simon Guggenheim Memorial FoundationUNSPECIFIED
Harvard UniversityUNSPECIFIED
Binational Science Foundation2004386
Subject Keywords:galaxies: clusters: general; galaxies: formation; dark matter; cosmology: theory
Issue or Number:3
Record Number:CaltechAUTHORS:20100714-142517955
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19049
Deposited By: Tony Diaz
Deposited On:05 Aug 2010 18:52
Last Modified:09 Mar 2020 13:19

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