A STUDY OF THE DARK CORE IN A520 WITH THE HUBBLE SPACE TELESCOPE: THE MYSTERY DEEPENS
- Department of Physics, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States)
- Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94131 (United States)
- Leiden Observatory, Leiden University, Leiden (Netherlands)
- Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada)
- Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)
- Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
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 10{sigma} significance. The {approx}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.
- OSTI ID:
- 22016259
- Journal Information:
- Astrophysical Journal, Vol. 747, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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