From the Heliosphere, to Galaxy Clusters, Gamma Ray Bubbles, Pulsars and Black Holes: Unexpected Plasmas, Relevant and Laboratory Based Theories (speaker: Bruno Coppi, MIT)
The in situ exploration of the Heliosphere has revealed the existence of unexpected kinds of plasmas and magnetic field configurations around the most distant planets (e.g. Uranus and Neptune) for which reliable theories can be formulated and be of help to envision the environments of a variety of recently discovered exo-planets. On larger scales, radically different kinds of plasmas have been found: in particular plasmas with “temperatures in the tens of keV are observed to be the main visible component of Galaxy Clusters, while g-ray emitting plasma structures (“bubbles”) have been seen to emerge from the disk of Our Galaxy with dimensions of the same order as those characterizing the Galaxy. Although the theory of the plasmas that can surround pulsars has a long history, the fact that the plasmas on the surface of pulsars can have inhomogeneous features (such as hot spots) and dynamics has gained attention recently. Given the very high magnetic fields involved, the role of the electron thermal conductivity anisotropy is shown to be an important factor in these.
There are important issues to be resolved in order to envision the plasmas that can surround black holes. These involve the structures that can form, such as rings and tridimensional spirals, the kind of transport of angular momentum that is needed to allow plasma accretion on the black hole, etc. In fact, laboratory experiments on high-energy plasmas have cast new light on basic processes that include the nature of angular momentum transport not described by a diffusion equation, magnetic reconnection events and associated production of high-energy particles, self-organization processes, etc.
Talk Host: Brendan Griffen