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Free keywords:
General Relativity and Quantum Cosmology, gr-qc, Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
A novel hierarchical semicoherent technique is presented for all-sky surveys
for continuous gravitational-wave sources, such as rapidly spinning
non-axisymmetric neutron stars. Analyzing year-long detector data sets over
realistic ranges of parameter space using fully-coherent matched-filtering is
computationally prohibitive. Thus more efficient, so-called hierarchical
techniques are essential. Traditionally, the standard hierarchical approach
consists of dividing the data into non-overlapping segments of which each is
coherently analyzed and subsequently the matched-filter outputs from all
segments are combined incoherently. The present work proposes to break the data
into subsegments being shorter than the desired maximum coherence time span
(size of the coherence window). Then matched-filter outputs from the different
subsegments are efficiently combined by "sliding" the coherence window in time:
Subsegments whose time-stamps are closer than coherence window size are
combined coherently, otherwise incoherently. Compared to the standard scheme at
the same coherence time baseline, data sets longer by about 50% - 100% would
have to be analyzed to achieve the same search sensitivity as with the sliding
coherence window approach. Numerical simulations attest the analytically
estimated improvement.
