Assessing the turbulent pressure in galaxy clusters

The amount of turbulent pressure support from residual gas motions at the periphery of galaxy clusters is not well known. In this work, we tested different choices for the filtering of laminar and bulk gas motions from simulated datasets, and we produced new analysis of turbulence in galaxy clusters with a large catalog of cluster simulations. In particular, we have explored the application of different filtering scales for the velocity field, exploring the range from 60 to 600 kiloparsec, in order to disentangle laminar from turbulent motions. We also apply a tailored shocks finding algorithm to minimise their contribution to the estimated turbulent budget. We study the ratio of non-thermal pressure versus total pressure and its radial behavior, finding that it is well described by a simple polynomial formula. The typical non-thermal pressure support we measured in the center of cluster is 3%, while this reaches 10% in the outskirts. We have also compared our results with recent numerical and observational literature. In particular, we found that the different definition of turbulent velocity generates very different amount of turbulent support. As we also discussed in a related paper, the fitting procedure which we used is more statistically significant than the ones presented in literature. Our results allow us to compare with recent observations, and assess which turbulent spatial scale best reproduces the observed trends. We also studied the relations between non-thermal support and cluster’s mass or dynamical state. In particular, our tests have shown that there are not any strong correlations between these quantities. We conclude that our no complete mass selection of the sample affect the study of any possible correlation. Some of the key results of this Thesis are already part of a work which is submitted and will be further documented in a dedicated scientific paper.