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

Understand

Sensitive surveys of the Cosmic Microwave Background will detect thousands of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect.

• Two SZ observables, the central or maximum and integrated Comptonization parameters y_max and Y, relate in a simple way to the total cluster mass, which allow the construction of mass functions (MFs) that can be used to estimate cosmological parameters such as Omega_M, sigma_8, and the dark energy parameter w.
• However, clusters form from the mergers of smaller structures, events that can disrupt the equilibrium of intracluster gas upon which SZ-M relations rely.
• From a set of N-body/hydrodynamical simulations of binary cluster mergers, we calculate the evolution of Y and y_max over the course of merger events and find that both parameters are transiently "boosted," primarily during the first core passage.