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Free keywords:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc
Abstract:
We conduct searches for continuous gravitational waves from seven pulsars,
that have not been targeted in continuous wave searches of Advanced LIGO data
before. We target emission at exactly twice the rotation frequency of the
pulsars and in a small band around such frequency. The former search assumes
that the gravitational wave quadrupole is changing phase-locked with the
rotation of the pulsar. The search over a range of frequencies allows for
differential rotation between the component emitting the radio signal and the
component emitting the gravitational waves, for example the crust or
magnetosphere versus the core. Timing solutions derived from the Arecibo
327-MHz Drift-Scan Pulsar Survey (AO327) observations are used. No evidence of
a signal is found and upper limits are set on the gravitational wave amplitude.
For one of the pulsars we probe gravitational wave intrinsic amplitudes just a
factor of 3.8 higher than the spin-down limit, assuming a canonical moment of
inertia of $10^{38}$ kg m$^2$. Our tightest ellipticity is $1.7 \times
10^{-8}$, which is a value well within the range of what a neutron star crust
could support.
