The frequency with which background galaxies appear as long arcs as a result of gravitational lensing by foreground clusters of galaxies has recently been found to be a very sensitive probe of cosmological models by Bartelmann et al .
( 1998 ) .
They have found that such arcs would be expected far less frequently than observed ( by an order of magnitude ) in the currently favored model for the universe , with a large cosmological constant \Omega _ { \Lambda } \sim 0.7 .
Here we analyze whether including the effect of cluster galaxies on the likelihood of clusters to generate long-arc images of background galaxies can change the statistics .
Taking into account a variety of constraints on the properties of cluster galaxies , we find that there are not enough sufficiently massive galaxies in a cluster for them to significantly enhance the cross section of clusters to generate long arcs .
We find that cluster galaxies typically enhance the cross section by only \lesssim 15 \% .