Searches for continuous gravitational waves from unknown sources attempt to detect long-lasting gravitational radiation by identifying Doppler-modulated signatures in the data. Semicoherent methods allow for wide parameter space surveys, identifying interesting regions to be followed up using more sensitive (and computationally expensive) tools. Thus, it is required to properly understand the parameter space structure under study, as failing to do so could significantly affect the effectiveness of said strategies. We introduce a new measure for distances in parameter space suited for semicoherent continuous wave searches. This novel approach, based on comparing time-frequency tracks, can be applied to any kind of quasimonochromatic continuous wave signals and adapts itself to the underlying structure of the parameter space under study. In a first application to the post-processing stage of an all-sky search for continuous waves from neutron stars in binary systems, we demonstrate a search sensitivity improvement by solely replacing previous ad hoc distance measures in the candidate clustering procedure by the new proposal.
This work was supported by European Union FEDER funds, the Ministry of Science, Innovation and Universities and the Spanish Agencia Estatal de Investigación Grants No. PID2019–106416 GB-I00/AEI/10.13039/501100011033, No. FPA2016-76821-P, No. RED2018-102661-T, No. RED2018-102573-E, No. FPA2017-90687-REDC, Comunitat Autonoma de les Illes Balears through the Direcció General de Política Universitaria i Recerca with funds from the Tourist Stay Tax Law ITS 2017-006 (PRD2018/24), Generalitat Valenciana (No. PROMETEO/2019/071), EU COST Actions No. CA18108, No. CA17137, No. CA16214, and No. CA16104. R. T. is supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (Ref. FPU 18/00694). D. K. is supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (Ref. BEAGAL 18/00148) and cofinanced by the Universitat de les Illes Balears. The authors thankfully acknowledge the computer resources at CTE-Power and the technical support provided by Barcelona Supercomputing Center—Centro Nacional de Supercomputación through Grant No. AECT-2019-3-0011 from the Red Española de Supercomputación (RES).