Search for gravitational-wave transients associated with magnetar bursts during the third Advanced LIGO and Advanced Virgo observing run

TL;DR

This paper reports on searches for gravitational waves associated with magnetar flares during LIGO and Virgo's third observing run, aiming to detect signals from excited neutron star modes and oscillations.

Contribution

It introduces minimally modeled, coherent search methods for gravitational waves linked to magnetar flares, including both short and long-duration signals, and discusses their sensitivity and implications.

Findings

No gravitational wave detections were made.

The search methods set upper limits on gravitational wave amplitudes.

Results inform models of magnetar flare mechanisms.

Abstract

Magnetars are neutron stars with exceptionally strong dipole magnetic fields which are observed to display a range of x-ray flaring behavior, but the flaring mechanism is not well understood. The third observing run of Advanced LIGO and Virgo extended from April 1, 2019 to March 27, 2020, and contained x-ray flares from known magnetar SGR 1935+2154, as well as the newly-discovered magnetar, Swift J1818-1607. We search for gravitational waves coincident with these magnetar flares with minimally modeled, coherent searches which specifically target both short-duration gravitational waves produced by excited f-modes in the magnetar's core, as well as long-duration gravitational waves motivated by the Quasi-Periodic Oscillations observed in the tails of giant flares. In this paper, we report on the methods and sensitivity estimates of these searches, and the astrophysical implications.