Open AccessKeck spectroscopy of Cosmic Lens All‐Sky Survey gravitational lenses
Author(s) -
McKean J. P.,
Koopmans L. V. E.,
Browne I. W. A.,
Fassnacht C. D.,
Blandford R. D.,
Lubin L. M.,
Readhead A. C. S.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07630.x
Subject(s) - physics , astrophysics , galaxy , gravitational lens , astronomy , einstein radius , strong gravitational lensing , redshift , sky , weak gravitational lensing , spectrograph , spectral line
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 ( z s = 3.1240 ± 0.0042) and the lensing galaxy redshifts in CLASS B0445+123 ( z 1 = 0.5583 ± 0.0003) and CLASS B0850+054 ( z l = 0.5883 ± 0.0006) . Intriguingly, we also discovered that CLASS B0631+519 may have two lensing galaxies ( z l,1 = 0.0896 ± 0.0001, z l,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.