Properties of scalar wave emission in a scalar-tensor theory with kinetic screening

TL;DR

This paper investigates scalar wave emissions from neutron stars in a scalar-tensor gravity theory with kinetic screening, revealing that monopole emissions are suppressed by screening while quadrupole emissions depend on the screening radius relative to the wave wavelength.

Contribution

It provides a numerical analysis of scalar wave emissions, highlighting the conditions under which screening suppresses monopole and quadrupole modes in scalar-tensor theories.

Findings

Monopole emission is always suppressed by screening.

Quadrupole suppression depends on screening radius and wave wavelength.

Further studies needed on neutron star binaries for comprehensive understanding.

Abstract

We study numerically the scalar wave emission by a non-spherical oscillation of neutron stars in a scalar-tensor theory of gravity with kinetic screening, considering both the monopole and quadrupole mode emission. In agreement with previous results in the literature, we find that the monopole is always suppressed by the screening effect, regardless of the size of the screening radius, $r_{\rm sc}$. For the quadrupole mode, however, our analysis shows that the suppression only occurs for screening radius larger than the wavelength of scalar waves, $\lambda_{\rm wave}$, but not for $r_{\rm sc} < \lambda_{\rm wave}$. This demonstrates that to fully understand the nature of this theory, it is necessary to study other more complex systems, such as neutron star binaries, considering a wide range of $r_{\rm sc}$ values.