Post-Newtonian Limits and Gravitational Radiation from the Superstring Effective Action

TL;DR

This paper explores the post-Newtonian gravitational effects and radiation predictions from superstring effective actions, highlighting additional monopole and dipole radiation components beyond standard quadrupole emission.

Contribution

It develops post-Newtonian field equations for superstring effective actions with axion-matter couplings and analyzes gravitational radiation, revealing new monopole and dipole contributions.

Findings

Derived post-Newtonian solutions for spinning masses and cosmic strings.

Identified monopole and dipole radiation components in superstring gravity.

Suggested potential observational tests in binary systems.

Abstract

We consider the gravitational sector of the superstring effective action with axion-matter couplings. The field equations are developed in the post-Newtonian scheme and approximate solutions for a spinning point mass and a cosmic string are presented. Furthermore, assuming vanishing axion mass and vanishing potential for the dilaton, we consider the gravitational radiation in the leading $O(\alpha'^0)$ order. We find that the total luminosity of a radiative source has monopole and dipole components besides the standard quadrupole one. These components may possibly be checked in binary systems.