Earth rotation and time-domain reconstruction of polarization states for continuous gravitational waves from a known pulsar

TL;DR

This paper investigates how Earth's rotation affects the detection of continuous gravitational waves from known pulsars, enabling polarization state reconstruction and constraining extra polarization modes in a general metric theory.

Contribution

It introduces a method to reconstruct polarization waveforms in the time domain from a single detector and discusses constraints on extra polarization modes.

Findings

Unique waveform reconstruction for each polarization state.

Constraints on propagation speeds of additional polarization modes.

Effects of Earth's rotation and pulsar spin variations analyzed.

Abstract

We consider effects of the Earth rotation on antenna patterns of a ground-based gravitational wave (GW) detector in a general metric theory that allows at most six polarization states (two spin-0, two spin-1 and two spin-2) in a four-dimensional spacetime. By defining the cyclically averaged antenna matrix for continuous GWs from a known pulsar, we show that waveforms for each polarization state can be uniquely reconstructed in time domain from a given set of the strain outputs at a single detector. Constraining the propagation speed of extra polarization modes, if they coexist with the transverse-traceless modes, is also discussed. We examine also possible effects due to the length-of-day modulation as well as a secular change in the pulsar spin period.