A new case of gravitational lensing
Abstract
Even before the discovery of the first gravitational lens system1 in 1979 (see ref. 2 for a recent review of the other published candidates), it was recognized that a statistical evaluation of the occurrence of gravitational lensing within a well-defined sample of quasars is important to understand better the quasar luminosity function and possibly the QSO phenomenon itself3, to test cosmological models4,5 and to probe the luminous and dark matter distribution on various scales in the Universe4-6. A year ago, we began a systematic search from the European Southern Observatory (ESO) at La Silla, Chile, for gravitational lens systems in a selected sample of highly luminous quasars; Mv<-29.0. These objects are promising candidates for gravitationally lensed QSO images with arc-second and sub-arc-second separations (J.S. et al., manuscript in preparation and refs 7 and 8). Since December 1986, we have identified four possible cases. Here we give a brief description of our first identified gravitational lens system UM673 = Q0142-100 =PHL37039-11. It consists of two images, A (mR = 16.9) and B (mR = 19.1), separated by 2.2arcs at a redshift zq = 2.719. The lensing galaxy (mR~ 19, ZL~0.49) has also been found. It lies very near the line connecting the two QSO images, ~0.8 arc s from the fainter one. Application of gravitational optometry to this system leads to a value M0~2.4×1011Msolar for the mass of the lensing galaxy and to δt~7 weeks for the most likely travel-time difference between the two light paths to the QSO (assuming H0= 75 km s-1 Mpc-1,q0 = 0).
- Publication:
-
Nature
- Pub Date:
- October 1987
- DOI:
- 10.1038/329695a0
- Bibcode:
- 1987Natur.329..695S
- Keywords:
-
- Gravitational Lenses;
- Quasars;
- Galaxies;
- Spectrum Analysis;
- Astrophysics