Binary neutron star mergeres: simulations with arbitrarily spinning stars

The starting point of any general relativistic numerical simulation is a solution
of the Hamiltonian and momentum constraints that (ideally) represents an astrophysically realistic scenario. This dissertation presents a new method to produce initial data sets for binary neutron stars with arbitrary spins and orbital eccentricities. The method only provides approximate solutions to the constraints. However, it was
shown that the corresponding constraint violations subside after a few orbits, becoming
comparable to those found in evolutions of standard conformally flat, helically
symmetric binary initial data. This dissertation presents the first spinning neutron
star binary simulations in circular orbits with a orbital eccentricity less then 0.01. The
initial data sets corresponding to binaries with spins aligned, zero and anti-aligned
with the orbital angular momentum were evolved in time. These simulations show
the orbital “hang-up” effect previously seen in binary black holes. Additionally, they
show orbital eccentricities that can be up to one order of magnitude smaller than
those found in helically symmetric initial sets evolutions.