The presence of non-thermal motions in clusters of galaxies plays a relevant role in the determination of their total mass. Indeed, cosmological simulations reveal that cluster masses derived from the assumption of hydrostatic equilibrium can underestimate the real values significantly.
Among the coherent (i.e. non-turbulent) motions of the baryonic cluster components, rotation in particular can be assessed trough a variety of indicators, through observations of the diffuse hot gas and the component galaxies.
We propose in this project the study of the main multi-wavelength observables that can reveal the rotation of baryonic matter within clusters, applied on hydrodynamical cosmological simulations.
We use the high-resolution clusters of the MUSIC dataset to produce the mock data for the study of three observables: (i) the temperature maps of the kinematic component of the Sunyaev-Zel'dovich effect
(ii) X-ray emission spectra from heavy elements in the intracluster gas (iii) spectroscopy-derived velocities of the component galaxies in the optical band.
We will make a feasibility study to address these techniques for the detection of a rotation of real clusters, in order to establish whether it could be observed with the most advanced high-resolution instruments, by applying these analysis techniques to a suitable sample of targets.
The innovativity of this project can be assessed through different aspects: we focus on a challenging observational target that has been poorly explored up to now, especially at millimetric wavelengths;
we produce for the first time the temperature maps of the kinematic Sunyaev-Zel'dovich effect of high-resolution hydrodynamical simulations of galaxy clusters; we combine for the first time three different and independent observational approaches to the same data to make a feasibility study of future observations.
With a quantitative indication of the amount of coherent rotation in clusters it would be possible to quantify a consistent fraction of the dynamical mass, which contributes to the total mass estimate together with the mass derived from the assumption of hydrostatic equilibrium. Having an accurate measurement of cluster masses is fundamental not only for astrophysical purposes, but also to use clusters as probes for cosmology.