2008ApJ...679L..81Q

In a galaxy cluster, galaxies are mostly collisionless particles in recent epochs. They resemble collisionless cold dark matter particles in some way. Therefore, the spatial distributions of dark matter and cluster galaxies might be expected to possess similar features in the gravitational potential of a cluster. Here we use the galaxy distribution in cluster Cl 0024+17 to probe for the ringlike dark matter structure recently discovered by means of strong and weak lensing observations. The galaxies are taken from the catalog of Czoske et al., which contains 650 objects with measured redshifts, of which ∼300 galaxies have redshifts in the range 0.37<z<0.41 (and are therefore probable cluster members). We find that, at about the 3 σ level, the ringlike structure seen in the dark matter measurement is not observed in the projected two-dimensional galaxy distribution.