Speaker
Description
Neutron stars serve as natural laboratories for exploring the physics of matter at nuclear densities. Accurate neutron star radius estimates can give us insight into such physics by constraining the equation of state of cold dense matter. As neutron star radii are too small to be directly measured, these estimates may come from comparing surface thermal flux observations to neutron star thermal flux models. These models depend on correctly modeling how fast rotation alters the stellar shape. There are several competing methods, known as shape functions, to model the stellar shape in the literature. This raises the question of which, if any, is the most accurate.
In this poster, I present the ongoing results of our investigation into the accuracy of shape functions. We introduce NS-SWORD (Neutron-Star Schwarzschild with Oblate Rotational Deformations), a computational model for solid angles and fluxes from distant neutron stars within the Oblate Schwarzschild approximation. Utilizing this code, we quantify how these functions differ from exact surfaces computed utilizing numerical relativity codes (RNS), how those differences propagate into differential and total solid-angle calculations relevant for flux modeling, and determine criteria for how accurate a shape function must be. We currently find that no single shape function is accurate across all compactness and spin regimes, but in our ongoing work, it appears possible to determine a single set of criteria for a more accurate shape function.
