Scalar Gravitational Wave Signals from Core Collapse in Massive Scalar-Tensor Gravity with Triple-Scalar Interactions

TL;DR

This paper investigates scalar gravitational wave signals from core collapse in massive scalar-tensor gravity theories with triple-scalar interactions, highlighting how these interactions influence wave amplitudes and their potential detectability with future detectors.

Contribution

It introduces the effects of triple-scalar self-interactions on scalarization and gravitational wave signals in massive scalar-tensor theories, and assesses their detectability with upcoming observatories.

Findings

Self-coupling suppresses scalarization amplitude.

Self-interacting effects are negligible during propagation.

Future detectors can potentially observe these signals at high SNR.

Abstract

The spontaneous scalarization during the stellar core collapse in the massive scalar-tensor theories of gravity introduces extra polarizations (on top of the plus and cross modes) in gravitational waves, whose amplitudes are determined by several model parameters. Observations of such scalarization-induced gravitational waveforms therefore offer valuable probes into these theories of gravity. Considering a triple-scalar interactions in such theories, we find that the self-coupling effects suppress the magnitude of the scalarization and thus reduce the amplitude of the associated gravitational wave signals. In addition, the self-interacting effects in the gravitational waveform are shown to be negligible due to the dispersion throughout the astrophysically distant propagation. As a consequence, the gravitational waves observed on the Earth feature the characteristic inverse-chirp pattern. Although not with the on-going ground-based detectors, we illustrate that the scalarization-induced gravitational waves may be detectable at a signal-to-noise ratio level of ${\cal O}(100)$ with future detectors, such as Einstein Telescope and Cosmic Explorer.