Cosmic Ray (Stochastic) Acceleration from a Background Plasma

We give a short review of processes of stochastic acceleration in the Galaxy. We discuss: how to estimate correctly the number of accelerated particles, and at which condition the stochastic mechanism is able to generate power-law nonthermal spectra. We present an analysis of stochastic acceleration in the Galactic halo and discuss whether this mechanism can be responsible for production of high energy electrons there, which emit gamma-ray and microwave emission from the giant Fermi bubbles. Lastly, we discuss whether the effects of stochastic acceleration can explain the CR distribution in the Galactic disk (CR gradient).
Comment: A talk presented at the conference "Cosmic Ray Origin - beyond the standard models" (San-Vito, Italy, 2016), submitted to Nuclear and Particle Physics Proceedings