Global parameter-space correlations of coherent searches for continuous gravitational waves

TL;DR

This paper investigates the global correlations in the parameter space of coherent searches for continuous gravitational waves, revealing that Earth's orbital velocity primarily determines the correlation circles, with detector motion affecting amplitude.

Contribution

It provides an analytical understanding of the global parameter-space correlations for short to intermediate observation times, focusing on the case without spindowns.

Findings

Correlation circles are mainly determined by Earth's orbital velocity.

Detector spin-motion influences the amplitude along these circles.

Global correlation structures can be analytically characterized for specific observation durations.

Abstract

The space of phase-parameters (sky-position, frequency, spindowns) of a coherent matched-filtering search for continuous gravitational waves from isolated neutron stars shows strong global correlations (``circles in the sky''). In the local limit this can be analysed in terms of a parameter-space metric, but the global properties are less well studied. In this work we report on our recent progress in understanding these global correlations analytically for short to intermediate (less than a month, say) observation times and neglecting spindowns. The location of these correlation-circles in parameter-space is found to be determined mostly by the orbital velocity of the earth, while the spin-motion of the detector and the antenna-patterns only contribute significantly to the amplitude of the detection statistic along these circles.