A directed continuous-wave search from neutron stars in binary systems with the five-vector resampling technique

TL;DR

This paper introduces a five-vector resampling technique for directed continuous gravitational-wave searches from neutron stars in binary systems, applied to LIGO-Virgo-KAGRA data, setting upper limits on undetected signals.

Contribution

The paper presents a novel five-vector resampling algorithm enabling efficient searches for CW signals from binary neutron stars, specifically applied to Scorpius X-1 data.

Findings

No significant CW signals detected in the analyzed data.

Set 95% confidence upper limits on CW amplitude.

Evaluated the sensitivity of the search method.

Abstract

Continuous gravitational-wave signals (CWs), which are typically emitted by rapidly rotating neutron stars with non-axisymmetric deformations, represent particularly intriguing targets for the Advanced LIGO-Virgo-KAGRA detectors. These detectors operate within sensitivity bands that encompass more than half of the known pulsars in our galaxy existing in binary systems, which are the targeted sources of this paper. However, the detection of these faint signals is especially challenged by the Doppler modulation due to the source's orbital motion, typically described by five Keplerian parameters, which must be determined with high precision to effectively detect the signal. This modulation spreads the signal across multiple frequency bins, resulting in a notable reduction of signal-to-noise ratio and potentially hindering signal detection. To overcome this issue, a robust five-vector resampling data-analysis algorithm has been developed to conduct thorough directed/narrowband CW searches at an affordable computational cost. We employ this methodology for the first time to search for CWs from Scorpius X-1, using publicly available data from the third observing run of the Advanced LIGO-Virgo-KAGRA detectors. No statistically significant CW signals can be claimed. Hence, we proceeded setting 95% confidence-level upper limits in selected frequency bands and orbital parameter ranges, while also evaluating overall sensitivity.