  We investigate empirical scaling relations between the thermal
Sunyaev-Zeldovich effect (SZE) and cluster mass in simulated clusters of
galaxies. The simulated clusters have been compiled from four different samples
that differ only in their assumed baryonic physics. We show that the strength
of the thermal SZE integrated over a significant fraction of the virialized
region of the clusters is relatively insensitive to the detailed heating and
cooling processes in the cores of clusters by demonstrating that the derived
scaling relations are nearly identical between the four cluster samples
considered. For our synthetic images, the central Comptonization parameter
shows significant boosting during transient merging events, but the integrated
SZE appears to be relatively insensitive to these events. Most importantly, the
integrated SZE closely tracks the underlying cluster mass. Observations through
the thermal SZE allow a strikingly accurate mass estimation from relatively
simple measurements that do not require either parametric modeling or geometric
deprojection and thus avoid assumptions regarding the physics of the ICM or the
symmetry of the cluster. This result offers significant promise for precision
cosmology using clusters of galaxies.
