Physical Properties of Spiral Structures in Gravitationally Interacting Disk Galaxies

다국어 초록 (Multilingual Abstract)

We explore gravitational interactions of a galactic disk with Toomre parameter Q ? 2 embedded in rigid halo/bulge with a point mass companion moving in a prescribed parabolic orbit. Tidal structures that form include bridge and tail in outer disks and spiral density waves in inner disks, which are all transient. In the near side to the perturber, strong tidal force locks the epicycle phases of particles and carving them into a sharp bridge almost corotating with the companion. A tail develops in the opposite side as the strongly-perturbed, near-side particles overtake the mildly- perturbed, far-side particles. In the inner disk, on the other hands, two-armed logarithmic spiral density waves emerge due to the kinematic alignment of perturbed particle orbits. The spiral waves attain the peak amplitudes rapidly and then decay and wind up in a time scale of 1 Gyr. The pattern speeds of the arms in all the models vary with both radius and time and converge to Ω - 1/2к, at late time, suggesting that the self-gravity is unimportant in the formation and maintenance of the arms. We present the parametric dependences of various properties of tidal features on the tidal strength, and discuss our findings in application to tidal spiral arms in grand-design spiral galaxies. We also conduct fully self-consistent three-dimensional simulation with 10 million particles. The preliminary result from the three-dimensional simulations agrees quantitatively with the two-dimensional restricted models.

목차 (Table of Contents)

• ABSTRACT
• INTRODUCTION
• NUMERICAL SIMULATIONS
• RESULTS
• REFERENCES