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Astrophysics, Gravitation and Cosmology Seminar - Matt Kunz (Princeton)

Event Type
Department of Physics
Via Zoom
wifi event
Jan 20, 2021   12:00 pm  
Matt Kunz (Princeton)
Brandy Shier
Originating Calendar
Physics - Astrophysics, Gravitation, and Cosmology Seminar

Cosmic Magnetism and Plasma Microphysics
(or, I get by with help from my little friends)

The Universe is magnetized. While magnetic-field strengths of just ~10^{-18} G are required to achieve this both in our Galaxy and in clusters of galaxies, observations of Faraday rotation, Zeeman splitting, and synchrotron emission all make the case of ubiquitous ~μG fields. That these systems are not content with hosting weaker fields is surprising, at least until one realizes that the energy density of a ~μG field is comparable to that of the observed turbulent motions. It is then natural to attribute the amplification and sustenance of (at least the random component of) the interstellar and intracluster magnetic fields to the fluctuation (or “turbulent”) dynamo. In this talk, we will explore the various ways in which plasma microphysics makes magnetic-field amplification in weakly collisional plasmas by macroscale turbulent motions both possible and efficient, with application to the intracluster medium of galaxy clusters. The predictions of this work are consistent with (i) deep Chandra X-ray observations of turbulence in the Coma cluster that suggest an anomalously low viscosity, (ii) recent LOFAR observations of diffuse radio emission in massive clusters when the Universe was only half of its present age, and (iii) plasma kinetics measured directly by in situ spacecraft in the solar wind. This research is part of an ongoing program of kinetic calculations aimed at elucidating from first principles the physics of waves, turbulence, heating, and transport in magnetized, weakly collisional astrophysical plasmas.

Zoom link will be sent to the astro@physics.illinois.edu mailing list. There will be an informal meet-and-greet with the speaker at 11:30am Central.

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