How can we measure neutron star radii?

Cole Miller

April 29, 2013

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Abstract: The matter in the cores of neutron stars is in an unknown state: various nuclear theories predict that neutrons, or quarks, or hyperons, or condensates might make up the majority of the composition. As we cannot access the required supranuclear cold matter in terrestrial laboratories, observations of neutron stars are the only way that we can constrain the properties of this exotic state. Masses of several stars have been measured, but radii, which arguably would provide the most important information, remain elusive. I will discuss various attempts to measure neutron star radii and the systematic errors that bedevil these attempts, and talk about future prospects including measurements using X-ray burst oscillation light curves and gravitational waves.