Neutron Star Dynamics in the Era of Gravitational Wave Astronomy

• Applicant: Professor Dr. Kostas Kokkotas, Ph.D.
• Subject Area: Astrophysics and Astronomy ; Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413873357

Neutron stars are the densest objects in the present Universe. These unique and irreproducible laboratories allow us to study physics in some of its most extreme regimes. The multifaceted nature of neutron stars involves a delicate interplay among astrophysics, gravitational physics, and nuclear physics as it was demonstrated by the recent discovery of merging neutron stars. In a few dozens papers published simultaneously across several journals, this spectacular event linked to a vast range of already observed phenomena and provided fresh insights on everything from fundamental nuclear physics to the large-scale evolution of the universe.This event together with the preceding discoveries of black-hole mergers turned gravitational physics into an observational science. Many more discoveries are expected to come in the next five years within the operation of Advanced LIGO, Virgo, KAGRA, and INDIGO and in the decades to follow with the operation of next generation detectors.Gravitational Waves by tight binary neutron star systems, supernovae explosions, non-axisymmetric or unstable spinning neutron stars will provide us with a unique opportunity to make major breakthroughs in not only gravitational physics, but also in particle and high-energy astrophysics.In this project we are planning to expand gravitational wave asteroseismology to fast rotating neutron stars by taking into account for the first time the contribution of a dynamical spacetime. The results will be mainly used to model and study gravitational wave signals from merging neutron stars and gravitational collapse. We expect to deliver information about the sequence of events, the details of nuclear equation of state and to provide constraints in the amplification of magnetic fields. The universal relations among the various associated observables (frequencies and damping/growth of oscillations, moment of inertia, compactness) can be used to link the observations in electromagnetic and gravitational wave spectrum with the structure of the associated objects and the sequence of events that take place during the very short but extremely dynamical period of their life.

• DFG Programme: Research Grants