12:00–1:00 pm ERC 501
Host: Vikram Dwarkadas
Anastasia Sokolenko "TeV halos and magnetic turbulences"
Neutron stars are amazing systems that host many interesting phenomena, both in terms of astrophysics and fundamental physics. Many of these phenomena are not yet understood. A recent example is given by the observation of macroscopic (~20 pc) areas around pulsars which are sources of diffuse TeV emission (the so-called TeV halos). The existence of these halos means that high-energy cosmic rays produced near the neutron star are very efficiently kept close to the neutron star, implying a diffusion coefficient ~ 2 orders of magnitude lower than in the interstellar medium. I will briefly describe several models that could explain these phenomena and pay special attention to one model that is based on MHD effects that might take place near a neutron star.
Emily Lichko "Differentiating between particle heating and energization processes in space and astrophysical plasmas"
Understanding the physics of particle heating and energization processes in space and astrophysical plasmas, including magnetic reconnection, instabilities, energy transfer through the turbulent cascade, and particle heating at shocks, is important to understand the evolution of larger-scale systems. In realistic simulations it can be difficult to disentangle competing kinetic-scale energy dissipation processes or to resolve processes that occur locally in both time and space. In this talk, I will review a recent technique developed to resolve the local rate of energy transfer between the fields and particles, called the field-particle correlation (Klein & Howes APJL 2016). I'll also detail an updated version of the field-particle correlation that we have developed that allows us to separate out the frequency at which the plasma is being energized, a critical component of differentiating between instabilities. To illustrate this method I'll use a classic resonant wave-particle instability, Landau damping.
