LIGO Document P2300182-v1

[Dissertation]: Searching for Gravitational Waves Associated with Flaring Galactic Magnetars

Document #:
LIGO-P2300182-v1
Document type:
P - Publications
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Abstract:
The third observing run of Advanced LIGO and Virgo (O3) took place from
April 1st, 2019 to September 30th, 2019, and from November 1st, 2019 to March
27th, 2020. The multi-messenger astronomy efforts during O3 included conducting
gravitational-wave follow-up searches to electromagnetic burst sources, specifically
Gamma-Ray Bursts, Fast Radio Bursts (FRBs), and magnetar x-ray bursts. The
overarching goal of the research described in this dissertation is to improve the
sensitivity of the LIGO burst searches in the third observing run, and to expand on
our data analysis methods for the next observing run.
Magnetars are highly magnetized neutron stars with intermittent x-ray
bursting behavior. We present a gravitational-wave follow-up search on the
magnetar bursts from O3. This is an expansion on a similar search that was done
in the second observing run (O2), and we present the differences in search methods
and their effects. We place the most stringent upper limits on gravitational wave
energy of any gravitational-wave search to date, and while these upper limits are
still not low enough to be astrophysically meaningful, they do provide a framework
for future searches. FRBs are short-duration, bright bursts of radio signal from far outside Milky
Way galaxy. We conduct the first-ever search for unmodeled gravitational-wave
transients coincident with FRBs detected by the Canadian Hydrogen Intensity
Mapping Experiment, the largest population of FRBs detected so far. We search
over both repeating and non-repeating FRBs. Although we find no evidence for a
signal, the study does lay the groundwork for future FRB searches from sources
within our detection radius.
A stacked search in which multiple triggers are analyzed simultaneously is
motivated by a number of very marginal triggers in the O3 magnetar search. We
develop a version of an existing LIGO burst pipeline that can perform a stacked
analysis. We describe the methods, and demonstrate a reduction in the root-sum-
squared strain that an unstacked event would need to have if it were to be detected
in a stacked analysis with a specific p-value. We also present sensitivity studies to
determine how to optimize our pipeline.
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