The Astrophysical Journal Letters Volume 648 Number 2
Douglas Clowe et al. 2006 ApJ 648 L109 doi:10.1086/508162
A Direct Empirical Proof of the Existence of Dark Matter*
Douglas Clowe1, Maruša Bradač2, Anthony H. Gonzalez3, Maxim Markevitch4,5, Scott W. Randall4, Christine Jones4, and Dennis Zaritsky1
dclowe@as.arizona.edu
1 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721
2 Kavli Institute for Particle Astrophysics and Cosmology, P.O. Box 20450, MS 29, Stanford, CA 94309
3 Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611
4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138
5 Also at the Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117997, Russia
Abstract
We present new weak-lensing observations of 1E 0657-558 (z = 0.296), a unique cluster merger, that enable a direct detection of dark matter, independent of assumptions regarding the nature of the gravitational force law. Due to the collision of two clusters, the dissipationless stellar component and the fluid-like X-ray-emitting plasma are spatially segregated. By using both wide-field ground-based images and HST/ACS images of the cluster cores, we create gravitational lensing maps showing that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies. An 8 σ significance spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law and thus proves that the majority of the matter in the system is unseen.
Footnote * Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, under program 10200, with the 6.5 m Magellan telescopes located at Las Campanas Observatory, Chile, with the ESO telescopes at the Paranal Observatory under program IDs 72.A-0511, 60.A-9203, and 64.O-0332, and with the NASA Chandra X-Ray Observatory, operated by the Smithsonian Astrophysics Observatory under contract to NASA. Subject headings
dark matter; galaxies: clusters: individual (1E 0657–558); gravitational lensing
Dates
Issue 2 (2006 September 10)
Received 2006 June 6, accepted for publication 2006 August 3
Published 2006 August 30
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