2021/01/12 by F Vivanco, Hernandez-Vivanco, Francisco, P. D. Lasky +13
Physics and Astronomy · Earth and Planetary Sciences · #Pulsars and Gravitational Waves Research #Geophysics and Gravity Measurements
paper · pdf · doi:10.48550/arxiv.2101.04782
Neutron stars offer the opportunity to study the behaviour of matter at densities and temperatures inaccessible to terrestrial experiments. Gravitational-wave observations of binary neutron star coalescences can constrain the neutron-star equation of state before and after merger. After the neutron star binary merges, hyperons can form in the remnant, changing the behaviour of the neutron-star equation of state. In this study, we use finite-entropy equations of state to show that a post-merger remnant can spin up due to cooling. The magnitude of the spin-up depends on the neutron-star equation of state. If hyperons are present, the post-merger spin-up changes the peak gravitational-wave frequency by ∼ 540 Hz, when the entropy per baryon drops from s=2 kB to s=0 kB. If hyperons are not present, the post-merger spin-up changes by ∼ 360 Hz, providing a gravitational-wave signature for exotic matter. We expect the same qualitative behaviour whenever temperature dependent phase transitions are triggered.