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The discovery of two giant arcs in the rich cluster A2219 with the Keck telescope

Smail, Ian and Hogg, David W. and Blandford, Roger and Cohen, Judith G. and Edge, Alastair C. and Djorgovski, S. George (1995) The discovery of two giant arcs in the rich cluster A2219 with the Keck telescope. Monthly Notices of the Royal Astronomical Society, 277 (1). pp. 1-10. ISSN 0035-8711. doi:10.1093/mnras/277.1.1.

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We report the discovery with the Keck telescope of two new multiply imaged arcs in the luminous X-ray cluster A2219 (z = 0.225). The brighter arc in the field is red and we use spectroscopic and photometric information to identify it as a z ~ 1 moderately star-forming system. The brightness of this arc suggests that it is formed from two merging images of the background source, and we identify possible candidates for the third image of this source. The second giant arc in this cluster is blue and, while fainter than the red arc, it has a similarly large angular extent (32 arcsec). This arc comprises three images of a single nucleated source - the relative parities of the three images are discernible in our best-resolution images. The presence of several bright multiply imaged arcs in a single cluster allows detailed modelling of the cluster mass distribution, especially when redshift information is available. We present a lensing model of the cluster, which explains the properties of the various arcs, and we contrast this model with the optical and X-ray information available on the cluster. We uncover significant differences between the distributions of mass and X-ray gas in the cluster. We suggest that such discrepancies may indicate an on-going merger event in the cluster core, possibly associated with a group around the second brightest cluster member. The preponderance of similar merger signatures in a large fraction of the moderate-redshift clusters would indicate their dynamical immaturity.

Item Type:Article
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URLURL TypeDescription Paper
Smail, Ian0000-0003-3037-257X
Hogg, David W.0000-0003-2866-9403
Blandford, Roger0000-0002-1854-5506
Cohen, Judith G.0000-0002-8039-4673
Djorgovski, S. George0000-0002-0603-3087
Additional Information:© 1995 Royal Astronomical Society. Provided by the NASA Astrophysics Data System. Accepted 1995 May 11. Received 1995 April 27; in original form 1995 January 31. This paper is based on observations obtained at both the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California, and the Hale Telescope of the Palomar Observatory. We thank Bev Oke for leading the construction of the LRIS spectrograph. Jim McCarthy and Jim Westphal are thanked for their work in providing an. efficient U imaging capability on the Hale 5-m and Jim Schombert for providing his U filter. We acknowledge helpful discussions with Richard Ellis, Jean-Paul Kneib, Jordi Miralda-Escude and especially Ann Zabludoff. Support via a NATO Advanced Fellowship (IRS), NSF Graduate Fellowship (DWH), NSF grant AST92-23370 (RDB) and partial support from a NSF PYI award AST-9157412 (SGD) is gratefully acknowledged. Finally, it is a pleasure to thank the W. M. Keck Foundation and its President, Howard B. Keck, for a generous grant that made the W. M. Keck Observatory possible.
Funding AgencyGrant Number
North Atlantic Treaty Organization (NATO)UNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: clusters: individual: A2219, galaxies: evolution, galaxies: formation, galaxies: photometry, cosmology: observations, gravitational lensing
Issue or Number:1
Record Number:CaltechAUTHORS:20170409-080326932
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Official Citation:Ian Smail, David W. Hogg, Roger Blandford, Judith G. Cohen, Alastair C. Edge, S. George Djorgovski; The discovery of two giant arcs in the rich cluster A2219 with the Keck telescope, Monthly Notices of the Royal Astronomical Society, Volume 277, Issue 1, 1 November 1995, Pages 1–10,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76448
Deposited By: 1Science Import
Deposited On:04 Apr 2018 17:29
Last Modified:15 Nov 2021 17:00

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