Abstract

Astronomical observations of neutron stars inform our understanding of matter at the highest densities. Already, we have used the gravitational-wave data of GW170817 - the first signal from merging neutron stars – to constrain the equation of state of dense matter in neutron stars. The heavy neutron-star merger GW190425 indicated that the gravitational-wave population may include heavier stars not previously observed in galactic double neutron star binaries. For distant sources, the distribution of masses in neutron-star mergers will be a key observable in the coming years of gravitational-wave astronomy. In this talk, I will discuss methods being used to explore matter and mass properties for LIGO /Virgo neutron stars. I will discuss how these results fit with other neutron-star observations, outline prospects of learning about matter in the current Advanced-detector era, and extrapolate to the potential of next-generation gravitational-wave observatories to map the phase diagram of dense neutron-rich matter and the endpoints of stellar evolution.