# Search for transient gravitational wave signals associated with magnetar bursts during Advanced LIGO's second observing run

## TL;DR

This study searched for gravitational waves associated with magnetar bursts during Advanced LIGO's second run, setting upper limits on strain and energy, but found no evidence of such signals.

## Contribution

First search during Advanced LIGO's second run for gravitational waves from magnetar bursts, improving strain sensitivity by a factor of 10 over previous searches.

## Key findings

- No gravitational wave signals detected.
- Set upper bounds on strain and energy for magnetar bursts.
- Improved sensitivity compared to previous LIGO runs.

## Abstract

We present the results of a search for short and intermediate-duration gravitational-wave signals from four magnetar bursts in Advanced LIGO's second observing run. We find no evidence of a signal and set upper bounds on the root sum squared of the total dimensionless strain ($h_{\text{rss}}$) from incoming intermediate-duration gravitational waves ranging from $1.1 \times 10^{-22}$ at 150 Hz to $4.4 \times 10^{-22}$ at 1550 Hz at 50% detection efficiency. From the known distance to the magnetar SGR 1806-20 (8.7 kpc) we can place upper bounds on the isotropic gravitational wave energy of $3.4 \times 10^{44} \text{erg}$ at 150 Hz assuming optimal orientation. This represents an improvement of about a factor of 10 in strain sensitivity from the previous search for such signals, conducted during initial LIGO's sixth science run. The short duration search yielded upper limits of $2.1 \times 10^{44} \,\text{erg}$ for short white noise bursts, and $2.3\times 10^{47}\,\text{erg}$ for $100 \, \text{ms}$ long ringdowns at 1500 Hz, both at 50% detection efficiency.