TIME-DEPENDENT STOCHASTIC ACCELERATION MODEL FOR FERMI BUBBLES

Fermi gamma-ray "bubbles" from stochastic acceleration of electrons.

Gamma-ray data from Fermi Large Area Telescope reveal a bilobular structure extending up to ∼50° above and below the Galactic Center. It has been argued that the gamma rays arise from hadronic interactions of high-energy cosmic rays which are advected out by a strong wind, or from inverse-Compton scattering of relativistic electrons accelerated at plasma shocks present in the bubbles. We explor...

Fermi Acceleration in a periodically Driven Fermi-Ulam Model

A consistent approach for the treatment of Fermi acceleration in time-dependent billiards.

The standard description of Fermi acceleration, developing in a class of time-dependent billiards, is given in terms of a diffusion process taking place in momentum space. Within this framework, the evolution of the probability density function (PDF) of the magnitude of particle velocities as a function of the number of collisions n is determined by the Fokker-Planck equation (FPE). In the lite...

Fermi Acceleration

Fermi acceleration is a mechanism, first suggested by Enrico Fermi in 1949, to explain heating of particles in cosmic rays. Fermi studied charged particles being reflected by the moving interstellar magnetic field and either gaining or losing energy, depending on whether the ”magnetic mirror” is approaching or receding. In a typical environment, Fermi argued, the probability of a head-on collis...

Stochastic Electron Acceleration in the TeV SNR RX J1713.7-3946 III: Time-Dependent Acceleration

We discuss the generic characteristics of stochastic particle acceleration by fully developed turbulence in collisionless plasmas and show that resonant interactions of particles with high-speed waves dominate the acceleration process. To produce the relativistic electrons inferred from the broadband spectrum of a few well-observed shell-type TeV supernova remnants (STTSNRs) in the leptonic sce...