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General Relativity and Quantum Cosmology, gr-qc, Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
We report results of a wideband search for periodic gravitational waves from
isolated neutron stars within the Orion spur towards both the inner and outer
regions of our Galaxy. As gravitational waves interact very weakly with matter,
the search is unimpeded by dust and concentrations of stars. One search disk
(A) is $6.87^\circ$ in diameter and centered on
$20^\textrm{h}10^\textrm{m}54.71^\textrm{s}+33^\circ33'25.29"$, and the other
(B) is $7.45^\circ$ in diameter and centered on
$8^\textrm{h}35^\textrm{m}20.61^\textrm{s}-46^\circ49'25.151"$. We explored the
frequency range of 50-1500 Hz and frequency derivative from $0$ to $-5\times
10^{-9}$ Hz/s. A multi-stage, loosely coherent search program allowed probing
more deeply than before in these two regions, while increasing coherence length
with every stage.
Rigorous followup parameters have winnowed initial coincidence set to only 70
candidates, to be examined manually. None of those 70 candidates proved to be
consistent with an isolated gravitational wave emitter, and 95% confidence
level upper limits were placed on continuous-wave strain amplitudes. Near $169$
Hz we achieve our lowest 95% CL upper limit on worst-case linearly polarized
strain amplitude $h_0$ of $6.3\times 10^{-25}$, while at the high end of our
frequency range we achieve a worst-case upper limit of $3.4\times 10^{-24}$ for
all polarizations and sky locations.