Strong lensing optical depths in a LCDM universe II: the influence of the stellar mass in galaxies

Understand

We investigate how strong gravitational lensing in the concordance LCDM cosmology is affected by the stellar mass in galaxies.

• We extend our previous studies, based on ray-tracing through the Millennium Simulation, by including the stellar components predicted by galaxy formation models.
• We find that the inclusion of these components greatly enhances the probability for strong lensing compared to a `dark matter only' universe.
• The identification of the `lenses' associated with strong-lensing events reveals that the stellar mass of galaxies (i) significantly enhances the strong-lensing cross-sections of group and cluster halos, and (ii) gives rise to strong lensing in smaller halos, which would not produce noticeable effects in the absence of the stars.