A novel hierarchical search technique is presented for all-sky surveys forcontinuous gravitational-wave sources, such as rapidly spinning nonaxisymmetricneutron stars. Analyzing yearlong detector data sets over realistic ranges ofparameter space using fully coherent matched-filtering is computationallyprohibitive. Thus more efficient, so-called hierarchical techniques areessential. Traditionally, the standard hierarchical approach consists ofdividing the data into nonoverlapping segments of which each is coherentlyanalyzed and subsequently the matched-filter outputs from all segments arecombined incoherently. The present work proposes to break the data intosubsegments shorter than the desired maximum coherence time span (size of thecoherence window). Then matched-filter outputs from the different subsegmentsare efficiently combined by sliding the coherence window in time: Subsegmentswhose timestamps are closer than coherence window size are combined coherently,otherwise incoherently. Compared to the standard scheme at the same coherencetime baseline, data sets longer by about 50-100% would have to be analyzed toachieve the same search sensitivity as with the sliding coherence windowapproach. Numerical simulations attest to the analytically estimatedimprovement.
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