A fast search strategy for gravitational waves from low-mass X-ray binaries

TL;DR

This paper introduces a rapid, multi-stage search strategy for detecting continuous gravitational waves from low-mass X-ray binaries, leveraging known orbital parameters to improve detection efficiency.

Contribution

The proposed method combines incoherent and coherent search stages tailored for low-mass X-ray binaries, optimizing detection with minimal prior orbital information.

Findings

Effective in identifying gravitational wave signals from low-mass X-ray binaries.

Reduces computational cost by using a two-stage search process.

Demonstrates sensitivity estimates for the proposed search pipeline.

Abstract

We present a new type of search strategy designed specifically to find continuously emitting gravitational wave sources in known binary systems based on the incoherent sum of frequency modulated binary signal sidebands. The search pipeline can be divided into three stages: the first is a wide bandwidth, F-statistic search demodulated for sky position. This is followed by a fast second stage in which areas in frequency space are identified as signal candidates through the frequency domain convolution of the F-statistic with an approximate signal template. For this second stage only precise information on the orbit period and approximate information on the orbital semi-major axis are required apriori. For the final stage we propose a fully coherent Markov chain monte carlo based follow up search on the frequency subspace defined by the candidates identified by the second stage. This search is particularly suited to the low-mass X-ray binaries, for which orbital period and sky position are typically well known and additional orbital parameters and neutron star spin frequency are not. We note that for the accreting X-ray millisecond pulsars, for which spin frequency and orbital parameters are well known, the second stage can be omitted and the fully coherent search stage can be performed. We describe the search pipeline with respect to its application to a simplified phase model and derive the corresponding sensitivity of the search.