Erlangen 2026 – wissenschaftliches Programm

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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie

GR 2: Gravitational Waves I

GR 2.4: Vortrag

Montag, 16. März 2026, 17:00–17:15, KH 01.016

Effective Gravitoelectric Lagrangian for Neutron Star Dynamical Tides — •Felix Lichtner — Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Potsdam, Germany

The tidal deformations of neutron stars in binary systems can have a significant impact on the emitted waveforms of gravitational waves. Studying these effects provides a direct window into the internal dynamics of neutron stars, in particular their still unknown equation of state. We characterize the tidal dynamics of a rotating neutron star in an external gravitational field by a systematic construction of a Lagrangian in the framework of effective field theory. This Lagrangian is constructed from the degrees of freedom describing the leading order gravitoelectric effects for neutron stars modeled as a perfect fluid, as is done e.g. in [Gupta, Steinhoff, Hinderer (2021)]. Integrating out the gravitational interactions to third post Newtonian order, we produce an effective description of the gravitoelectric binary dynamics. Further, we characterize the tidal spin via an analysis of the symmetries in the Lagrangian. Finally, we show that the equations of motion as well as the stress-energy tensor attained from the Lagrangian reproduce the Mathisson–Papapetrou–Dixon (MPD) equations of motion describing general extended objects in General Relativity.

Keywords: Dynamical tides; Neutron stars; Effective field theory