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Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
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.