Hidden symmetry between rotational tidal Love numbers of spinning neutron stars

TL;DR

This paper uncovers a surprising hidden symmetry between rotational tidal Love numbers of spinning neutron stars, which influences gravitational wave signals and is independent of the star's internal composition.

Contribution

It provides numerical evidence for a previously unrecognized symmetry linking rotational tidal Love numbers of opposite parity in spinning neutron stars.

Findings

Identifies a hidden symmetry among rotational tidal Love numbers.

Shows the symmetry is independent of the neutron star's equation of state.

Supports the symmetry with numerical evidence.

Abstract

The coupling between the angular momentum of a compact object and an external tidal field gives rise to the "rotational" tidal Love numbers, which affect the tidal deformability of a spinning self-gravitating body and enter the gravitational waveform of a binary inspiral at high post-Newtonian order. We provide numerical evidence for a surprising "hidden" symmetry among the rotational tidal Love numbers with opposite parities, which are associated to perturbations belonging to separate sectors. This symmetry, whose existence had been suggested on the basis of a Lagrangian description of the tidal interaction in a binary system, holds independently of the equation of state of the star.