Gravothermal expansion in an N-body system

This paper describes the numerical evolution of an N-body system with a slight ``temperature inversion''; i. e. the maximum velocity dispersion occurs not at the centre but further out. Fluid models predict that the core of such a system expands on a time-scale of thousands of central relaxation times, and here this behaviour is qualitatively confirmed for an N-body system of over 3000 bodies. With certain qualifications, this demonstrates the existence in N-body systems of one of the fundamental mechanisms which, in fluid models, drive the gravothermal oscillations discovered by Bettwieser & Sugimoto.