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UM 425: a New Gravitational Lens Candidate

Meylan, G. and Djorgovski, S. (1988) UM 425: a New Gravitational Lens Candidate. Messenger, 54 . pp. 39-42. ISSN 0722-6691.

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Since the first theoretical discussions more than 50 years ago on the phenomenon of light rays bent by intervening mass in the universe (Eddington 1920, Einstein 1936, Zwicky 1937 a, b), gravitational lensing has steadily grown to become one of the most active fields of research in extragalactic astronomy today. There are numerous theoretical investigations (Refsdal 1964, 1966, Turner et al. 1984, Blandford and Narayan 1986, Blandford and Kochanek 1987a, b), but the observations of good gravitationallens candidates are still rare. It is only during the last decade that a few quasar systems have been found in reasonable agreement with the gravitational lensing interpretation, viz., 0957 + 561 (Walsh et al. 1979), 1115 + 080 (Weymann et al. 1980), 2016 + 112 (Lawrence et al. 1983), 2237 + 030 (Huchra et al. 1985), 0142-100 (Surdej et al. 1987), and 1413+ 117 (Magain et al. 1988). In other possible cases, e.g., 2345+007 ryveedman et al. 1982), and 1635+267 (Djorgovski and Spinrad 1984), there has so far been no detection of lensing galaxies, and thus they should possibly be considered as genuine pairs of interacting quasars, similar to the probable binary quasar PKS 1145-071 (Djorgovski et al. 1987). Recently, so-called giant luminous arcs have been observed in a few clusters of galaxies. They are interpreted as segments of Einstein rings, created because of an almost perfect alignment of the lensing cluster potential well with the lensed background object (Soucail et al. 1988, Lynds and Petrosian 1988). Blandford and Kochanek (1987) provide the most comprehensive and updated review on these subjects.

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Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1988 ESO. Provided by the NASA Astrophysics Data System. It is a pleasure to thank the staff of all observatories involved, and especially H. Pedersen and J. Miranda at ESO, J. Bravo and M. Navarete at CTIO, W. Kunkel and P. Schecter at Las Campanas, and J. Carrasco at Palomar. Many thanks also to R. Perley for obtaining and reducing the VLA snapshots.
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ID Code:97685
Deposited By: Tony Diaz
Deposited On:07 Aug 2019 16:38
Last Modified:03 Oct 2019 21:34

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