Galaxy orbits for galaxy clusters in the sloan digital sky survey and two degree field galaxy redshift survey

We present the results of a study for galaxy orbits in galaxy clusters using a spectroscopic sample of galaxies in SDSS and 2dFGRS. We have determined the member galaxies of Abell clusters covered by these surveys using the galaxies' redshift and positional data. We have selected 10 clusters using three criteria: the number of member galaxies is greater than or equal to 40, the spatial coverage is complete, and the X-ray mass profile is available in the literature. We derive the radial profile of the galaxy number density and velocity dispersion using all, early-type, and late-type galaxies for each cluster. We have investigated the galaxy orbits for our sample clusters with constant and variable velocity anisotropies over the clustercentric distance using the Jeans equation. Using all member galaxies, the galaxy orbits are found to be isotropic within the uncertainty for most of the sample clusters, although it is difficult to conclude strongly for some clusters due to the large errors and the variation as a function of the clustercentric distance in the calculated velocity anisotropies. We investigated the orbital difference between early-type and late-type galaxies for four sample clusters and found no significant difference between them.