Gravitational Lensing by a Compound Population of Halos: Standard Models

Based on observed rotation curves and theoretical simulations, there are reasons for believing that at least three different types of dark matter halos exist in the Universe classified by their masses M and the inner slope of mass density -\: Population A (galaxies): 10^10 h^-1 M_\ 10^13 h^-1 M_\, \ = 1. 3; and Population C (dwarf halos): M < 10^10 h^-1 M_\, \ = 1. 3. In this paper we calculate the lensing probability produced by such a compound population of dark halos, for both image separation and time delay, assuming that the mass function of halos is given by the Press-Schechter function and the Universe is described by an LCDM, OCDM, or SCDM model, all normalized to the abundance of rich clusters. We compare the predictions of the different cosmological models with observational data and show that, both LCDM and OCDM models are marginally consistent with the current available observational data, but the SCDM model is ruled out. The fit of the compound model to the observed relation between splitting angle and time delay is excellent but the fit to the number vs splitting angle relation is only adequate using the small number of sources in the objective JVAS/CLASS survey. A larger survey of the same type would have great power in discriminating among cosmological models. Furthermore, population C in an LCDM model has a unique signature in the time domain, which makes it distinguishable from variants of CDM scenarios, such as warm dark matter, repulsive dark matter, or collisional dark matter.