7 papers
The Lens-Redshift Test Revisited
Phillip Helbig
Kochanek (1992) suggested that the redshifts of gravitational lens galaxies rule out a large cosmological constant. This result was questioned by Helbig & Kayser (1996), who pointe…
The Current Status of CLASS
Phillip Helbig
I give a brief overview of the current status of some aspects of the Cosmic Lens All-Sky Survey (CLASS): description of the survey, current list of lens systems, cosmological param…
CLASS B0827+525: `Dark lens' or binary radio-loud quasar?
L. V. E. Koopmans, A. G. de Bruyn, C. D. Fassnacht +12
We present radio, optical, near-infrared and spectroscopic observations of the source B0827+525. We consider this source as the best candidate from the Cosmic Lens All-Sky Survey (…
Gravitational lensing statistics with extragalactic surveys. IV. Joint constraints from gravitational lensing statistics and CMB anisotropies
J. F. Macias-Perez, P. Helbig, R. Quast +2
We present constraints on the cosmological constant lambda_0 and the density parameter Omega_0 from joint constraints from the analyses of gravitational lensing statistics of the J…
Lensing galaxies: light or dark?
N. Jackson, P. Helbig, I. W. A. Browne +4
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…
Evolution in the Lyman-alpha forest
Thomas Liebscher, Rainer Kayser, Phillip Helbig
We reanalyse the spectra used by D.-E. Liebscher (no relation) et al with the same goal -- determining the cosmological parameters -- and basically the same assumptions but with a…