[28.13] A High Redshift Cluster on the Way to UM425

AAS 205th Meeting, 9-13 January 2005
Session 28 Lensing: Micro, MACHO, Strong, Weak and Wide
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

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[28.13] A High Redshift Cluster on the Way to UM425

P.J. Green (SAO), L. Infante (PUC), S. Lopez (U.Chile), T.L. Aldcroft (SAO), J.N. Winn (CfA)

UM425 is a wide (6.5arcsec) quasar pair with suspiciously similar spectra, both at z=1.47 and showing broad absorption lines. While no good lens candidate had previously been found, our 110ksec Chandra observation (Aldcroft & Green 2003) revealed weak diffuse emission near the quasar pair, and HST images showed a nearby excess of faint galaxies, suggesting a cluster or group of galaxies. We present VLT spectroscopy which identifies the cluster as very likely being along the sightline, to UM425. We discuss plausible lens models for the system.

We gratefully acknowledge support from NASA grant NAS8-03060 (CXC) and from CONICYT's FONDAP, Center for Astrophysics.

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