FTheory: Measuring the Neutron-Star Equation of State from Gravitational Wave Observations
Gravitational-wave observations of compact binaries containing neutron stars can be used to measure the unknown equation of state (EOS) of neutron-star matter. The dominant observable comes from tidal interactions which cause an accumulating phase shift during the inspiral. Although this effect can only be observed in loud single events, I will describe a method for stacking measurements of tidal interactions from multiple inspiral events. We use Markov chain Monte Carlo simulations to estimate the parameters of a parameterized EOS that can reproduce theoretical EOS models. We find that, for realistic event rates, combining a year of gravitational-wave data allows us to measure the EOS above nuclear density to better than a factor of two, and the neutron-star radius to +/-1km. Unfortunately, uncertainties in post-Newtonian waveform models lead to systematic errors in the EOS measurement that are as large as the statistical errors. I will discuss methods to speedup more accurate, but computationally expensive, models such as the effective one body model so that they can be used in parameter estimation to measure the EOS with minimal systematic errors.