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#### Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data

##### Fulltext (public)

2109.09255.pdf

(Preprint), 5MB

##### Supplementary Material (public)

There is no public supplementary material available

##### Citation

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, Abbott, R., Abbott, T. D., Acernese, F., et al. (in preparation). Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data.

Cite as: http://hdl.handle.net/21.11116/0000-0009-3F51-6

##### Abstract

Results are presented of searches for continuous gravitational waves from 20
accreting millisecond X-ray pulsars with accurately measured spin frequencies
and orbital parameters, using data from the third observing run of the Advanced
LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov
model, where the transition probabilities allow the frequency to wander
according to an unbiased random walk, while the $\mathcal{J}$-statistic
maximum-likelihood matched filter tracks the binary orbital phase. Three narrow
sub-bands are searched for each target, centered on harmonics of the measured
spin frequency. The search yields 16 candidates, consistent with a false alarm
probability of 30% per sub-band and target searched. These candidates, along
with one candidate from an additional target-of-opportunity search done for SAX
J1808.4$-$3658, which was in outburst during one month of the observing run,
cannot be confidently associated with a known noise source. Additional
follow-up does not provide convincing evidence that any are a true
astrophysical signal. When all candidates are assumed non-astrophysical, upper
limits are set on the maximum wave strain detectable at 95% confidence,
$h_0^{95\%}$. The strictest constraint is $h_0^{95\%} = 4.7\times 10^{-26}$
from IGR J17062$-$6143. Constraints on the detectable wave strain from each
target lead to constraints on neutron star ellipticity and $r$-mode amplitude,
the strictest of which are $\epsilon^{95\%} = 3.1\times 10^{-7}$ and
$\alpha^{95\%} = 1.8\times 10^{-5}$ respectively. This analysis is the most
comprehensive and sensitive search of continuous gravitational waves from
accreting millisecond X-ray pulsars to date.