THE MASS-L-x RELATION FOR MODERATE LUMINOSITY X-RAY CLUSTERS

We present measurements of the masses of a sample of 25 moderate X-ray luminosity clusters of galaxies from the 160 square degree ROSAT survey. The masses were obtained from a weak-lensing analysis of deep F814W images obtained using the Advanced Camera for Surveys. We present an accurate empirical correction for the effect of charge transfer (in)efficiency on the shapes of faint galaxies. A significant lensing signal is detected around most of the clusters. The lensing mass correlates tightly with the cluster richness. We measured the intrinsic scatter in the scaling relation between M-2500 and L-X to be sigma(log LX)vertical bar M = 0.23(-0.04)(+0.10). The best-fit power-law slope and normalization are found to be alpha = 0.68 +/- 0.07 and M-X = (1.2 +/- 0.12) x h(70)(-1)10(14) M-circle dot (for L-X = 2 x 10(44)h(70)(-2) erg s(-1)). These results agree well with a number of recent studies, but the normalization is lower compared to the study of Rykoff et al. One explanation for this difference may be the fact that (sub) structures projected along the line of sight boost both the galaxy counts and the lensing mass. Such superpositions lead to an increased mass at a given L-X when clusters are binned by richness.