On The Dynamics of Massive Eccentric Nuclear Disks

Wernke, Heather Nicole

Graduate Thesis Or Dissertation

On The Dynamics of Massive Eccentric Nuclear Disks Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/cf95jc78t

Abstract

The Andromeda Galaxy (M31) hosts an elongated nucleus that resolves into two distinct brightness peaks. The double nucleus is explained by an eccentric nuclear disk which consists of stars moving on apsidally-aligned orbits around a supermassive black hole. The same secular gravitational torques that dynamically stabilize these disks can produce tidal disruption events (TDEs) at very high rates. I use N-body simulations to show that this is true in both Newtonian gravity and with general relativistic precession. Additionally, I show that orbital elements between successive TDEs from eccentric nuclear disks are correlated.

The double nucleus in M31 may seem like an unusual feature, but many early-type galaxies in the local universe have asymmetric nuclei indicating the possible presence of eccentric nuclear disks. I create photometric (surface density) and kinematic (line-of-sight velocity) maps of eccentric nuclear disks using N-body simulations. By observing my simulations along many different lines of sight, I am able to classify them as double nuclei, offset nuclei, and centered nuclei. Observations of any of the photometric or kinematic signatures discussed here could be evidence for the potential of a galaxy hosting an eccentric nuclear disk.

Finally, I show that eccentric nuclear disks are not unique to galactic centers. Orbits cluster together in the scattered disk in the outer Solar System. The secular torques between orbits in the axisymmetric near-Keplerian disk cause a dynamical instability. After the inclination instability saturates, an eccentric nuclear disk forms. I present photometric and kinematic maps of the disk as the instability occurs and as the apsidal clustering persists afterwards. The observed clustering could explain the strange orbits of minor planets in the outer Solar System and is also expected to be found in exoplanetary systems.

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