Parameter-space metric for all-sky semicoherent searches for gravitational-wave pulsars

TL;DR

This paper introduces an approximation for the semicoherent parameter-space metric in all-sky gravitational-wave pulsar searches, revealing that these searches need significantly more templates than earlier estimates suggested.

Contribution

The paper presents a new approximation for the semicoherent metric, improving the understanding of template bank requirements in gravitational-wave pulsar searches.

Findings

Semicoherent searches require orders of magnitude more templates than previously estimated.

The new metric approximation aligns with previous coherent metric work and improves search efficiency.

Results impact the design and computational planning of all-sky pulsar searches.

Abstract

The sensitivity of all-sky searches for gravitational-wave pulsars is primarily limited by the finite availability of computing resources. Semicoherent searches are a widely-used method of maximizing sensitivity to gravitational-wave pulsars at fixed computing cost: the data from a gravitational-wave detector are partitioned into a number of segments, each segment is coherently analyzed, and the analysis results from each segment are summed together. The generation of template banks for the coherent analysis of each segment, and for the summation, requires knowledge of the metrics associated with the coherent and semicoherent parameter spaces respectively. We present a useful approximation to the semicoherent parameter-space metric, analogous to that presented in Wette and Prix [Phys. Rev. D 88, 123005 (2013)] for the coherent metric. The new semicoherent metric is compared to previous work in Pletsch [Phys. Rev. D 82, 042002 (2010)], and Brady and Creighton [Phys. Rev. D 61, 082001 (2000)]. We find that semicoherent all-sky searches require orders of magnitude more templates than previously predicted.