IAU Symposium Abstract S186-061P

The Interaction between Spherical Collisionless Systems

Y. Kan-ya1, S. Inagaki2
1 Kyoto Univ. < kanya@tap.scphys.kyoto-u.ac.jp >
2 Kyoto Univ. < inagaki@kusastro.kyoto-u.ac.jp >

We study the detailed process in the interaction between two dark halos of galaxies, by treating the dark halos as collisionless systems. We investigate the energy transport process of the orbital kinetic energy of two identical spherical collisionless systems into the internal energy of each system. We concentrate on the weak interaction which corresponds to the situation that the distance between each system is far. We formulate the problem by second-order perturbative approach. We solve the change of the energy of the collisionless particles in each system due to the fluctuation of the gravitational field, and add up the change in each system. We show that the contribution to the growth of the internal energy mainly comes from the resonance between the temporal fluctuation of the gravitational field and the quasi-periodic motion of collisionless particles in each system.