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Sensitive surveys of the Cosmic Microwave Background will detect thousands ofgalaxy clusters via the Sunyaev-Zel'dovich (SZ) effect. Two SZ observables, thecentral or maximum and integrated Comptonization parameters y_max and Y, relatein a simple way to the total cluster mass, which allow the construction of massfunctions (MFs) that can be used to estimate cosmological parameters such asOmega_M, sigma_8, and the dark energy parameter w. However, clusters form fromthe mergers of smaller structures, events that can disrupt the equilibrium ofintracluster gas upon which SZ-M relations rely. From a set ofN-body/hydrodynamical simulations of binary cluster mergers, we calculate theevolution of Y and y_max over the course of merger events and find that bothparameters are transiently "boosted," primarily during the first core passage.We then use a semi-analytic technique developed by Randall et al. (2002) toestimate the effect of merger boosts on the distribution functions YF and yF ofY and y_max, respectively, via cluster merger histories determined fromextended Press-Schechter (PS) merger trees. We find that boosts do not inducean overall systematic effect on YFs, and the values of Omega_M, sigma_8, and wwere returned to within 2% of values expected from the nonboosted YFs. Theboosted yFs are significantly biased, however, causing Omega_M to beunderestimated by 15-45%, sigma_8 to be overestimated by 10-25%, and w to bepushed to more negative values by 25-45%. We confirm that the integrated SZeffect, Y, is far more robust to mergers than y_max, as previously reported byMotl et al. (2005) and similarly found for the X-ray equivalent Y_X, and weconclude that Y is the superior choice for constraining cosmologicalparameters.

The Impact of Galaxy Cluster Mergers on Cosmological Parameter Estimation from Surveys of the Sunyaev-Zel'dovich Effect