Keck spectroscopy of Cosmic Lens All-Sky Survey gravitational lenses
Abstract
We present the optical spectra of four newly discovered gravitational lenses from the Cosmic Lens All-Sky Survey (CLASS). These observations were carried out using the Low-Resolution Imaging Spectrograph on the W. M. Keck-I Telescope as part of a programme to study galaxy-scale gravitational lenses. From our spectra, we found the redshift of the background source in CLASS B0128+437 (zs= 3.1240 +/- 0.0042) and the lensing galaxy redshifts in CLASS B0445+123 (z1= 0.5583 +/- 0.0003) and CLASS B0850+054 (zl= 0.5883 +/- 0.0006). Intriguingly, we also discovered that CLASS B0631+519 may have two lensing galaxies (zl,1= 0.0896 +/- 0.0001, zl,2= 0.6196 +/- 0.0004). We also found a single unidentified emission line from the lensing galaxy in CLASS B0128+437 and the lensed source in CLASS B0850+054. We find the lensing galaxies in CLASS B0445+123 and CLASS B0631+519 (l, 2) to be early-type galaxies with Einstein radii of 2.8-3.0 h-1 kpc. The deflector in CLASS B0850+054 is a late-type galaxy with an Einstein radius of 1.6 h-1 kpc.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2004
- DOI:
- 10.1111/j.1365-2966.2004.07630.x
- arXiv:
- arXiv:astro-ph/0402116
- Bibcode:
- 2004MNRAS.350..167M
- Keywords:
-
- gravitational lensing;
- quasars: individual: CLASS B0128+437;
- quasars: individual: CLASS B0445+123;
- quasars: individual: CLASS B0631+519;
- quasars: individual: CLASS B0850+054;
- Astrophysics
- E-Print:
- 9 pages, 5 figures, accepted for publication in MNRAS