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A Study of the Dark Core in A520 with the Hubble Space Telescope: The Mystery Deepens

Jee, M. J. and Mahdavi, A. and Hoekstra, H. and Babul, A. and Dalcanton, J. J. and Carroll, P. and Capak, P. (2012) A Study of the Dark Core in A520 with the Hubble Space Telescope: The Mystery Deepens. Astrophysical Journal, 747 (2). p. 96. ISSN 0004-637X. doi:10.1088/0004-637X/747/2/96.

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We present a Hubble Space Telescope/Wide Field Planetary Camera 2 weak-lensing study of A520, where a previous analysis of ground-based data suggested the presence of a dark mass concentration. We map the complex mass structure in much greater detail, leveraging more than a factor of three increase in the number density of source galaxies available for lensing analysis. The "dark core" that is coincident with the X-ray gas peak, but not with any stellar luminosity peak, is now detected with more than 10σ significance. The ~1.5 Mpc filamentary structure elongated in the NE-SW direction is also clearly visible. Taken at face value, the comparison among the centroids of dark matter, intracluster medium, and galaxy luminosity is at odds with what has been observed in other merging clusters with a similar geometric configuration. To date, the most remarkable counterexample might be the Bullet Cluster, which shows a distinct bow-shock feature as in A520, but no significant weak-lensing mass concentration around the X-ray gas. With the most up-to-date data, we consider several possible explanations that might lead to the detection of this peculiar feature in A520. However, we conclude that none of these scenarios can be singled out yet as the definite explanation for this puzzle.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mahdavi, A.0000-0002-8111-3343
Babul, A.0000-0003-1746-9529
Carroll, P.0000-0002-3191-5401
Capak, P.0000-0003-3578-6843
Additional Information:© 2012 American Astronomical Society. Received 2011 September 16; accepted 2011 December 27; published 2012 February 21. H. Hoekstra acknowledges support from the Netherlands Organisation for Scientific Research (NWO) through a VIDI grant. H. Hoekstra is also supported by a Marie Curie International Reintegration Grant. A. Babul acknowledges support from an NSERC Discovery grant. J. Dalcanton and A. Mahdavi acknowledge the support by NASA through program GO-11221. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under program 11221.
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Marie Curie International Reintegration GrantUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:cosmology: observations; dark matter; galaxies: clusters: individual (A520); galaxies: high-redshift; gravitational lensing: weak; X-rays: galaxies: clusters
Issue or Number:2
Record Number:CaltechAUTHORS:20120514-102651392
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Official Citation:A Study of the Dark Core in A520 with the Hubble Space Telescope: The Mystery Deepens M. J. Jee et al. 2012 ApJ 747 96
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31449
Deposited On:15 May 2012 15:09
Last Modified:09 Nov 2021 19:53

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