GALAXIES: FUNDAMENTAL PARAMETERS; COSMOLOGY: DARK MATTER; GRAVITATIONAL LENSING
Abstract :
[en] In a recent paper, Hawkins (1997) argues on the basis of statistical studies of double-image gravitational lenses and lens candidates that a large population of dark lenses exists and that these outnumber galaxies with more normal mass-to-light ratios by a factor of 3:1. If correct, this is a very important result for many areas of astronomy including galaxy formation and cosmology. In this paper we discuss our new radio-selected gravitational lens sample, JVAS/CLASS, in order to test and constrain this proposition. We have obtained ground-based and HST images of all multiple-image lens systems in our sample and in 12 cases out of 12 we find the lensing galaxies in the optical and/or near infrared. Our success in finding lensing galaxies creates problems for the dark lens hypothesis. If it is to survive, ad hoc modifications seem to be necessary: only very massive galaxies (Mga9 *E(11) M[SUB]sun[/SUB]) can be dark, and the cutoff in mass must be sharp. Our finding of lens galaxies in all the JVAS/CLASS systems is complementary evidence which supports the conclusion of Kochanek et al. (1997) that many of the wide-separation optically-selected pairs are physically distinct quasars rather than gravitational lens systems.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Jackson, Neal J. F.; University of Manchester, NRAL, Jodrell Bank, Macclesfield SK11 9DL, UK
Helbig, Phillip ; University of Manchester, NRAL, Jodrell Bank, Macclesfield SK11 9DL, UK
Browne, Ian W. A.; University of Manchester, NRAL, Jodrell Bank, Macclesfield SK11 9DL, UK
Fassnacht, Christopher D.; California Institute of Technology, Mail Code 105-24, Pasadena, CA 91125, USA
Koopmans, Lèon V. E.; Kapteyn Astronomical Institute, Postbus 800, 9700 AA, Groningen, The Netherlands
Marlow, Daniel R.; University of Manchester, NRAL, Jodrell Bank, Macclesfield SK11 9DL, UK
Wilkinson, Peter N.; University of Manchester, NRAL, Jodrell Bank, Macclesfield SK11 9DL, UK)