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.

Breve CV del Dr. Lorenzo Lovisari:

Lorenzo Lovisari si é laureato in astronomia all'Università di Bologna nel 2006. Ha fatto il dottorato all'Università di Innsbruck (Austria) e ottenuto il PhD nel 2010. Dal 2011 al 2015 ha svolto il suo primo postdoc all'Università di Bonn (Germania), mentre dal 2015 al 2020 é stato postdoc al CfA (U.S.A.). É rientrato in Italia per il terzo postdoc a INAF-OAS Bologna dal 2020 al 2023. Da marzo 2023 é ricercatore presso INAF-IASF Milano. Interesse scientifico: Studio delle proprietà chimiche e termodinamiche degli ammassi di galassie