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(gzipped) PostScript## Cosmology with galaxy clusters## III. Gravitationally lensed arc statistics as a cosmological probe
We calculate the expected number of gravitationally lensed optical, radio and sub-mm lensed sources on the whole sky due to foreground galaxy clusters for different cosmological models. We improve previous calculations of lensed arc statistics by including redshift information for background sources and accounting for the redshift evolution of the foreground lensing clusters. The background sources are described based on the redshift and optical magnitude or flux distribution for sources in the Hubble Deep Field (HDF). Using the HDF luminosity function, we also account for the magnification bias in magnitude-limited observational programs to find lensed optical arcs. The foreground lensing clusters are modeled as singular isothermal spheres, and their number density and redshift distribution is calculated based on the Press-Schechter theory with normalizations based on the local cluster temperature function. Based on the results from optical arc surveys, we find that the
observed number of arcs can easily be explained in a flat universe
() with low values for cosmological
mass density of the universe ().
However, given the large systematic and statistical uncertainties
involved with both the observed and predicted number of lensed arcs,
more reliable estimates of the cosmological parameters are not
currently possible. We comment on the possibility of obtaining a much
tighter constraint based on statistics from large area optical
surveys. At radio wavelengths (1.4 GHz), we predict
1500 lensed radio sources with flux
densities greater than 10
© European Southern Observatory (ESO) 1999 Online publication: December 16, 1998 |