Modeling of Gravitationally Lensed Images in Cluster Abell 2218

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Session 30 -- Clusters of Galaxies
Display presentation, Tuesday, 9:30-6:30, Pauley Room

[30.12] Modeling of Gravitationally Lensed Images in Cluster Abell 2218

V.Petrosian,D.W.Saraniti (Stanford University)

Abell 2218, with redshift $z=0.17$, is one of the first clusters in which gravitationally lensed arcs have been found (Lynds and Petrosian, 1986). A2218 contains several arcs, and although none are as large as some of the more studied arcs (A370, CL2244-02), they are interesting none the less. One arc in the cluster is redder than the typical galaxy which is unusual since most lensed arcs have a bluer color. The redshift of this arc is 0.704 (Petrosian and Lynds, 1992). There is an almost perfectly circular blue ring surrounding one galaxy. There are several other blue arclets including two, called the twin arcs, that are on either side of two close galaxies. We model the system with a simple mass distribution consisting of the visible galaxies and a diffuse dark matter component. We are able to model the red arc and the twin arcs, but find that the ring is most likely not a gravitationally lensed image. We also examine the X-ray distribution of the cluster and find that the dark matter component for the lensing models is more compact than the X-ray's and their centers are approximately $1'$ apart. This work is supported by NASA grant NAGW 2290 and a National Science Foundation Graduate Fellowship.

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