It is often assumed that, after the collapse of the main halo progenitor, the galaxy cluster gas settles in hydrostatic equilibrium into a spherically symmetric potential well. Under this assumption, all thermodynamic properties (e.g., temperature, density, and pressure) depend only on the distance from the center and are therefore homogeneous within a narrow radial shell. However, turbulent motions due to a large variety of other astrophysical ICM processes (e.g., sloshing, AGN feedback, thermal instabilities) can significantly alter the hydrostatic equilibrium at different scales. Thus, the complex physics of galaxy clusters may result in a high level of temperature and density substructures (i.e., fluctuations) which are tied to the dynamical history of the clusters. The presence of substructures may induce biases in the determination of cluster properties, such as global gas temperature or total mass (and therefore impact the scaling relations of galaxy clusters).

We used the spatially resolved 2D temperature and density distributions of 28 clusters to evaluate and characterize the level of gas inhomogeneities and the related dynamical state of the ICM. I will show how, by comparing the scatter of temperature and density profiles to hydrodynamic simulations, we constrained the average Mach number regime of the sample. Moreover, I will show how these results can provide an estimate of the ratio between turbulent and thermal energy, and therefore provide an independent estimate of the hydrostatic mass bias.

Brief CV of Dr. Lorenzo Lovisari:

Lorenzo Lovisari graduated in astronomy at the University of Bologna in 2006. He did his doctorate at the University of Innsbruck (Austria) where he got his PhD in 2010. From 2011 to 2015, he carried out his first postdoc at the University of Bonn (Germany), while from 2015 to 2020 he was a postdoc at the CfA (USA). He came back in Italy for his third postdoc at INAF-OAS Bologna from 2020 to 2023. Since March 2023 he is a researcher at INAF-IASF Milano. Scientific interest: Study of the chemical and thermodynamic properties of galaxy clusters