Friends-of-Friends Groups and Clusters in the 2SLAQ Catalogue
  We present a catalogue of galaxy groups and clusters selected using a
friends-of-friends algorithm with a dynamic linking length from the 2dF-SDSS
and QSO (2SLAQ) luminous red galaxy survey. The linking parameters for the code
are chosen through an analysis of simulated 2SLAQ haloes. The resulting
catalogue includes 313 clusters containing 1,152 galaxies. The galaxy groups
and clusters have an average velocity dispersion of sigma_v = 467.97 km/s and
an average size of R_clt = 0.78 Mpc/h. Galaxies from regions of one square
degree and centred on the galaxy clusters were downloaded from the Sloan
Digital Sky Survey Data Release 6 (SDSS DR6). Investigating the photometric
redshifts and cluster red-sequence of these galaxies shows that the galaxy
clusters detected with the FoF algorithm are reliable out to z~0.6. We estimate
masses for the clusters using their velocity dispersions. These mass estimates
are shown to be consistent with 2SLAQ mock halo masses. Further analysis of the
simulation haloes shows that clipping out low richness groups with large radii
improves the purity of catalogue from 52% to 88%, while retaining a
completeness of 94%. Finally, we test the two-point correlation function of our
cluster catalogue. We find a best-fitting power law model with parameters r0 =
24\pm4 Mpc/h and gamma = -2.1\pm 0.2, which are in agreement with other low
redshift cluster samples and consistent with a {\Lambda}CDM universe.
