Turbulence and Preferential Heating in Astrophysical Plasmas: Insights from the Earth's Magnetosheath

Astrophysical plasmas are typically collisionless, meaning they can deviate significantly from local thermodynamic equilibrium. This allows different particle species, such as protons and electrons, to sustain distinct temperatures. Observations suggest that turbulence plays a crucial role in transferring energy from large, energy-containing scales to small kinetic scales, where it is ultimately converted into plasma internal energy (heating). However, a key open question remains: how does turbulence partition energy between protons and electrons? Does it favor one species, or does it distribute energy evenly? This question is central to several major open problems, including the heating of the solar corona and the luminosity of accretion disks around black holes. Over the past two decades, significant theoretical and numerical efforts have been made to predict the proton-to-electron heating ratio. However, direct, extensive in-situ measurements remain scarce. Using data from NASA's Magnetospheric Multiscale (MMS) mission in the Earth's magnetosheath, we analyze how turbulence drives plasma heating through the pressure-strain interaction. We identify the scales at which heating becomes effective and explore how energy is partitioned between protons and electrons as a function of the plasma parameters. Our findings deepen our understanding of the interplay between turbulence and plasma heating, with implications for interpreting remote-sensing observations of astrophysical plasmas.