Institute of Astronomy

Revisiting relaxation in globular clusters

SpeakerTalk DateTalk Series
Chris Hamilton (DAMTP)15 June 2018Institute of Astronomy Galaxies Discussion Group

Abstract

The classical (Spitzer-Chandrasekhar) theory of cluster relaxation is
unsatisfactory because it involves the Coulomb logarithm and completely
neglects the cluster's self-gravity. A modern alternative is the
Balescu-Lenard (BL) equation, which has no such ill-defined parameter and
includes self-gravity. The BL equation has recently explained the secular
evolution of collisionless stellar discs. In this talk I will review the
classical theory and demonstrate its pitfalls, showing at each stage why the
BL equation does a better job. I will then present the first application of
the BL formalism to spherical systems. I will show how the BL flux through
action space differs from the corresponding classical flux, and discuss what
a complete theory of cluster relaxation might entail.

Presentation

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