Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Chair

Richard Lieu

Committee Member

Jack Fix

Committee Member

Max Bonamente

Committee Member

James Baird

Committee Member

Kenneth Howell

Committee Member

Leland Cseke


Dark energy (Astronomy), Cosmology., Expanding universe., Big bang theory., Astrophysics.


It is shown that at sufficiently large radii dark energy modifies the behavior of (a) bound orbits around a galaxy, and (b) virialized gas in a cluster of galaxies. In (a), there exists a maximum circular orbit beyond which periodic motion is no longer possible, and the evolution of orbits near critical binding is analytically calculable using an adiabatic invariant integral. The finding may have application to wide galaxy pairs. In (b), dark energy necessitates the use of the generalized Virial Theorem to describe gas at the outskirts of a cluster. As a result, gas at a radius of 4 Mpc or above will readily escape. A simple model indicates that this mechanism can lead to mass loss via an outflow.



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