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Published December 1997 | Published + Submitted
Journal Article Open

The External Shear Acting on Gravitational Lens B1422+231

Abstract

In a number of multiply imaged quasar systems, a significant contribution to the lensing potential is provided by groups and clusters of galaxies associated with the primary lens. As part of an ongoing effort to gather observational data on these systems, we present spectroscopy and near-infrared and optical photometry of galaxies in the field of the quadruple lens system B1422+231. The spectra show that the primary lens and five nearby galaxies belong to a compact group at ζ=0.338. The median projected radius of this group is 35h^(-1) kpc and its velocity dispersion is ˜550 km s^(-1). A straightforward application of the virial theorem yields a group mass of 1.4X10^(13)h^(-1) M⊙, which provides sufficient external shear to produce the observed image configuration. This data rules out a class of models and improves the system's prospects for a measurement of the Hubble constant.

Additional Information

© 1997 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1997 June 17; revised 1997 September 7; accepted 1997 September 10. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California. We are grateful to the W. M. Keck Foundation for the vision to fund the construction of the W. M. Keck Observatory. We thank Charles Lawrence, Keith Matthews, Gerry Neugebauer, and Tom Soifer for making their unpublished near-infrared data available. We benefited from helpful conversations with Sangeeta Malhotra and Michael Fahre. Financial support was provided by NSF Grants No. AST-92-23370 and No. AST 95-29170, and by NASA Grant No. NAG-5-3834. This research made use of NASA's Astrophysics Data System Abstract Service.

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Published - 1997AJ____114_2276K.pdf

Submitted - 9706169.pdf

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August 19, 2023
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