Published online by Cambridge University Press: 25 May 2016
We present the first clear evidence that the gravothermal oscillation takes place in N-body systems. We performed direct N-body simulations of systems of point-mass particles with particle numbers from 2,048 to 32,768. In the simulation with 32,768 particles, the central density shows an oscillation with an amplitude of ∼ 103, which is similar to what was observed in more approximate models such as a conducting gas sphere and one-dimensional Fokker-Planck calculations. The amplitude is smaller for a smaller number of particles. The number of particles in the core at the maximum contraction is ∼ 10 for all runs, while the number of particles at the maximum expansion is about 0.01N. For 16,384- and 32,768-body runs, the temperature inversion during the expansion phase is clearly visible.