Speaker
Description
The microphysical composition of neutron star cores remains an unresolved problem, with current multimessenger data being insufficient to identify the correct description of dense nuclear matter. Quarkyonic matter, where baryons coexist with quarks deep in the Fermi sea, provides a framework which naturally reconciles the issue of massive neutron stars with relatively small radii, made possible via a rapid rise of sound speed square ($c_{s}^2$) at core densities. Generating a large set of quarkyonic matter equations of state via Bayesian inference, all of which satisfy current astrophysical constraints from LIGO/Virgo and NICER, allowed to identify that presence of a quarkyonic phase in the stellar core causes the mass-radius curve's slope ($dR/dM$) to be generally positive. Coupling the $dR/dM$ evaluated at fixed mass with the $c_s^2$ at the star's center showed a distinct separation between neutron stars whose cores do (high sound speed with positive slope) or do not (low sound speed with negative slope) have a quarkyonic phase. These results define a concrete, testable signature of quarkyonic (or quarkyonic-like) phases that can be probed by next-generation X-ray, radio, and gravitational-wave observations capable of delivering precise radius measurements at multiple masses and improved inferences of the internal sound-speed profile.
