RUI: Building a Robust Software Infrastructure for Parameterizing and Measuring the Neutron Star Equation of State

Kenyon College, Gambier OH

Investigators

Abstract

This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. Two years ago, the historic detection of colliding neutron stars sent physical and figurative waves through the scientific community. Shortly after, the LIGO-Virgo Collaboration made the first direct measurement of the neutron star equation of state from gravitational waves. Many more binary neutron star mergers will be seen as ground-based interferometers continue operating and increasing in sensitivity. This promises to provide even tighter constraints on the equation of state. A critical component of this process will be developing the software infrastructure for modeling and measuring the neutron star equation of state. The Kenyon College LIGO group will develop and incorporate a full suite of equation of state models available not only to the collaboration, but also available to the broader scientific community who rely on these results for followup analyses. This award intimately involves undergraduates in LIGO research and supports a no-barrier-to-entry astronomy research program that can recruit and bridge students into important LIGO research. This award focusses on four types of equation of state models that will be used for parameter estimation: 1) piecewise polytopic models, 2) spectral decompositions of the adiabatic index, 3) models with built-in sharp, first-order phase transitions, and 4) models with nuclear physics parameters. Polytropic and spectral decomposition models have already been incorporated into lalsuite, which is LIGO’s algorithm library. However, they still require important development to make them more robust, which are great projects for training young undergraduates for more substantial research. Models with phase transitions and nuclear physics parameters have not yet been incorporated into lalsuite and will require a lot of development to get working seamlessly with the collaboration’s flagship parameter estimation software. Both sets of projects, though varying in required development, are essential additions for interpreting the physics of neutron star interiors. These projects could potentially lead to conclusive evidence of a first-order phase transition in the neutron star equation of state. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.