The Shining High-Energy Universe as a Plasma Astrophysicist's Playground

Event Dates: 

Wednesday, October 14, 2015 - 4:00pm

CTQM Seminar Type: 

  • Related Seminar Series

Speaker Name(s): 

Dmitri Uzdensky

Speaker Affiliation(s): 

University of Colorado, Boulder

Abstract, Event Details: 

Most of the visible, shining Universe (the regular, non-dark matter) is made of plasma, a hot ionized gas that can carry electric currents and thus generate and interact with electromagnetic fields.  Cosmic plasmas are complex, turbulent, almost always immersed in magnetic fields and often collisionless, with nonthermal particle distributions. Many of the most spectacular phenomena in our magnetized plasma Universe involve rapid and bright high-energy bursts and flares, often exhibiting nonthermal spectra. These violent events are believed to be powered by just a few basic kinetic plasma processes: turbulence, shocks, and magnetic reconnection (rapid rearrangement of magnetic field topology, leading to a violent release of magnetic energy).  Studying them is the realm of Plasma Astrophysics.  Often, the intense radiation produced by these energy dissipation processes exerts an strong backreaction on them, controlling their energetics and dynamics and hence their observational signals.  However, radiative effects (e.g., radiative cooling, radiation pressure, photon-drag resistivity, pair creation) have so far been largely ignored in traditional theoretical studies.  My research program aims at building a coherent theoretical framework for the new frontier — Radiative Plasma Astrophysics — and at exploring its astrophysical applications.  Most of my research so far has focused on radiative effects on magnetic reconnection. I will give an overview of my group’s research in this area, including the development of new computational tools capable of investigating radiative kinetic plasma processes, and I will illustrate our work with several important astrophysical applications.