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 .