Revealing the character of orbits in a binary system consisting of a primary galaxy and a satellite companion

TL;DR

This study models the orbits within a binary galaxy system to analyze how the presence of a dense nucleus and galaxy interactions influence the regularity or chaos of stellar motions, supported by numerical simulations and observational comparisons.

Contribution

It introduces a 3D galactic gravitational model to examine orbital behavior in binary systems, highlighting the impact of dense nuclei and galaxy interactions on chaos and regularity.

Findings

Chaotic orbits increase with a dense, massive nucleus.

Low-energy stars exhibit chaos near the galactic center for small intergalactic distances.

Regular motion dominates at larger distances in active galaxies.

Abstract

In this article, we present a galactic gravitational model of three degrees of freedom (3D), in order to study and reveal the character of the orbits of the stars, in a binary stellar system composed of a primary quiet or active galaxy and a small satellite companion galaxy. Our main dynamical analysis will be focused on the behavior of the primary galaxy. We investigate in detail the regular or chaotic nature of motion, in two different cases: (i) the time-independent model in both 2D and 3D dynamical systems and (ii) the time-evolving 3D model. Our numerical calculations indicate that the percentage of the chaotic orbits increases when the primary galaxy has a dense and massive nucleus. The presence of the dense galactic core also increases the stellar velocities near the center of the galaxy. Moreover, for small values of the distance R between the two bodies, low-energy stars display chaotic motion, near the central region of the galaxy, while for larger values of the distance R, the motion in active galaxies is entirely regular for low-energy stars. Our simulations suggest that in galaxies with a satellite companion, the chaotic nature of motion is not only a result of the galactic interaction between the primary galaxy and its companion, but also a result caused by the presence of the dense nucleus in the core of the primary galaxy. Theoretical arguments are presented in order to support and interpret the numerically derived outcomes. Furthermore, we follow the 3D evolution of the primary galaxy, when mass is transported adiabatically from the disk to the nucleus. Our numerical results are in satisfactory agreement with observational data obtained from the M51-type binary stellar systems. A comparison between the present research and similar and earlier work is also made.