First-post-Newtonian generation of gravitational waves in Einstein-Cartan theory

TL;DR

This paper extends the calculation of gravitational waves to Einstein-Cartan theory at the first post-Newtonian order, incorporating quantum spin effects via torsion and analyzing their impact on waveforms.

Contribution

It introduces a novel framework for including intrinsic spin and torsion in gravitational wave generation at the first post-Newtonian level.

Findings

Derived source multipole moments with high accuracy.

Analyzed the physical meaning of non-radiative moments.

Estimated the magnitude of spin contributions in gravitational waves.

Abstract

In this paper we investigate the gravitational-wave generation problem at the first post-Newtonian order in the context of Einstein-Cartan theory by exploiting the Blanchet-Damour formalism. The quantum intrinsic spin carried by slowly moving, weakly stressed, weakly self-gravitating sources is described geometrically by means of the torsion tensor. We obtain the expression of the source multipole moments with the required accuracy. The analysis of the physical meaning of the lowest-order non-radiative moments and of the asymptotic gravitational waveform is also performed. Eventually, we draw our conclusions and estimate the order of magnitude of the spin contributions in the gravitational-wave signal.