Schedule Mar 18, 2011
The Impact of Mergers in the Y - M Scaling Law in the MareNostrum Universe
Federico Sembolini (UAM)

The Sunyaev-Zel'dovich effect (SZE) is a powerful mass finder and the M - Y scaling law, based on the self similarity of cluster of galaxies, is the useful converter when observations of the Compton parameter Y are available. The presence of inhomogeneities in the IntraCluster gas (ICg), breaking the assumed spherical symmetry, isothermality and hydrostatic equilibrium, results in a scatter along the scaling law. The case of col- lision between two clusters, when gas and dark matter undergo different displacement, is a clear example of extreme situation of missing this symmetry. MareNostrum Universe (MNU), one of the biggest smoothed particle hydrodynamics (SPH) simulations, has been used for selecting a sample of mergers and relaxed clusters spanning a total mass in the range of 10^13 < M/M_SUN < 10^15

The objects of the selected datasets were resimulated with higher resolution and adding non-adiabatic physics (cooling and star formation), performing an analysis of baryonic fraction and thermal Sunyaev-Zel'dovich effect in the two classes in the redshift range 0 < z < 1. We found that the morphology of the cluster affects the baryonic fraction and the integrated Y (introducing a dependence from the position of the observer), leading to possible uncertainties in the scaling relations.

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