Gravitational waves from protoneutron stars and nuclear equation of state

Abstract

We examine the frequencies of the gravitational waves radiating from the protoneutron star produced via the core‐collapse supernova. In a way similar to the cold neutron star, we find that the frequencies of the w1 and f mode gravitational waves can be, respectively, expressed well as a function of the stellar compactness and the stellar average density at each time step after core bounce. Thus, via the simultaneous detection of both the f and w1 mode gravitational waves, one can determine the protoneutron star mass and radius at each time step. Unlike the cold neutron star, the protoneutron star mass and radius are changing with time because of the mass accretion and cooling, which enables us to identify the equation of state for the high‐density region in principle via only one event of supernova.