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

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 $\Delta t_c=0.21ms$, 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 $T_{eff}=740keV$, and the timescale for repeating a burst of $\gamma$-rays $\Delta {\tau }_R=11.3yr$. Altogether, we find the associated GW amplitude and frequency to be $h_c=2.7\times 10^{-23}/{(Hz)}^{1/2}$ and $f_{gw}=966Hz$, for a source distance $\sim 55kpc$. Detectability of the pulses by t he forthcoming GW anntenas is discussed and found likely.

5 pages, [prl]{revtex}, 1 PS figure included. To appear in Physical Review Letters