Gravitational-wave bursts from soft gamma-ray repeaters: Can they be detected?

TL;DR

This paper proposes a model where soft gamma-ray repeaters and gravitational-wave bursts originate from super-Eddington accreting neutron stars, estimating their emission characteristics and assessing the detectability with upcoming gravitational-wave detectors.

Contribution

It introduces a novel scenario linking SGRs and GW bursts via supercritical accretion in neutron stars, with detailed estimates of emission parameters and detection prospects.

Findings

Estimated GW amplitude of 2.7 x 10^-23 at 966 Hz.

Predicted gamma-ray burst recurrence timescale of 11.3 years.

Detected signals are likely with future GW detectors.

Abstract

In this letter we suggest a scenario for simultaneous emission of gravitational-wave and $\gamma$-ray bursts (GRBs) from soft gamma-ray repeaters (SGRs). we argue that both of the radiations can be generated by a super-Eddington accreting neutron stars in X-ray binaries. In this model a supercritical accretion transient takes back onto the remnant star the disk leftover by the hydrodynamic instability phase of a low magnetized, rapidly rotating neutron star in a X-ray binary system. We estimate the rise timescale $\Delta t_c = 0.21 ms$, minimum mass accretion rate needed to trigger the $\gamma$-ray emission, $\dot{M}_\lambda = 4.5 \times 10^{28} g$, and its effective associated temperature $T_{eff} = 740 keV$, and the timescale for repeating a burst of $\gamma$-rays $\Delta \tau_R = 11.3 yr$. Altogether, we find the associated GW amplitude and frequency to be $h_c = 2.7 \times 10^{-23}/{(Hz)}^{1/2}$ and $f_{gw} = 966 Hz$, for a source distance $\sim 55 kpc$. Detectability of the pulses by t he forthcoming GW anntenas is discussed and found likely.