Radialization of Satellite Orbits in Galaxy Mergers

We consider the orbital evolution of satellites in galaxy mergers, focusing on the evolution of eccentricity. Using a large suite of N -body simulations, we study the phenomenon of satellite orbital radialization—a profound increase in the eccentricity of its orbit as it decays under dynamical frict...

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Bibliographic Details
Published in:The Astrophysical journal 2022-02, Vol.926 (2), p.203
Main Authors: Vasiliev, Eugene, Belokurov, Vasily, Evans, N. Wyn
Format: Article
Language:English
Subjects:
Angular momentum
Astrophysics
Dynamical friction
Dynamical systems
Evolution
Friction
Galactic evolution
Galaxies
Galaxy mergers
Galaxy mergers & collisions
Many body problem
Orbit decay
Physical factors
Satellite orbits
Satellites
Simulation
Stars & galaxies
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Summary:We consider the orbital evolution of satellites in galaxy mergers, focusing on the evolution of eccentricity. Using a large suite of N -body simulations, we study the phenomenon of satellite orbital radialization—a profound increase in the eccentricity of its orbit as it decays under dynamical friction. While radialization is detected in a variety of different setups, it is most efficient in cases of high satellite mass, not very steep host density profiles, and high initial eccentricity. To understand the origin of this phenomenon, we run additional simulations with various physical factors selectively turned off: satellite mass loss, reflex motion and distortion of the host, etc. We find that all these factors are important for radialization because it does not occur for point-mass satellites or when the host potential is replaced with an unperturbed initial profile. The analysis of forces and torques acting on both galaxies confirms the major role of self-gravity of both host and satellite in the reduction of orbital angular momentum. The classical Chandrasekhar dynamical friction formula, which accounts only for the forces between the host and the satellite, but not for internal distortions of both galaxies, does not match the evolution of eccentricity observed in N -body simulations.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ac4fbc