Search for gravitational-wave bursts from soft gamma repeaters

Area of Science:

• Astrophysics
• Gravitational Wave Astronomy
• High-Energy Astrophysics

Background:

• Soft gamma-ray repeaters (SGRs) are neutron stars emitting powerful bursts of gamma rays.
• Neutron star f modes are theoretically predicted to be efficient sources of gravitational waves (GWs).
• Previous searches have not been sensitive to these specific GW emission modes from SGRs.

Purpose of the Study:

• To conduct the first search for short-duration gravitational waves (GWs) associated with SGR bursts.
• To test the hypothesis that SGR bursts emit detectable GWs, particularly from neutron star f modes.
• To establish new upper limits on the energy emitted as GWs during SGR events.

Main Methods:

• Utilized data from the Laser Interferometer Gravitational-Wave Observatory (LIGO).
• Searched for transient GW signals coincident with a catalog of SGR bursts, including a giant flare from SGR 1806-20 and 190 lesser events.
• Applied analysis techniques sensitive to neutron star f-mode GW emission.

Main Results:

• No statistically significant evidence for GWs was found associated with any of the observed SGR bursts.
• The study established the most stringent upper limits to date on transient GW amplitudes.
• Model-dependent upper limits on isotropic GW emission energies (at 10 kpc) ranged from 3x10^45 to 9x10^52 erg.

Conclusions:

• The absence of detected GWs places constraints on SGR burst models.
• The achieved sensitivity demonstrates the capability of current GW detectors to probe astrophysical phenomena.
• Upper limits are consistent with theoretical predictions for some SGR emission scenarios.