A comprehensive framework for phase-coherent mapping of the gravitational-wave sky with pulsar timing arrays

TL;DR

This paper introduces a phase-coherent mapping technique for pulsar timing arrays that captures the full polarisation state of gravitational waves, enabling comprehensive sky analysis within a unified framework.

Contribution

It presents a novel, practical implementation that preserves amplitude, phase, and polarisation in sky maps, improving upon standard cross-correlation methods for gravitational-wave detection.

Findings

Robust recovery of source amplitudes and locations demonstrated in simulations

Framework effectively handles noise, polarisation leakage, and array sensitivity variations

Compatible with existing pulsar timing data analysis methods

Abstract

We present a practical implementation of a phase-coherent mapping technique for pulsar timing arrays that resolves the full complex polarisation state of the gravitational-wave sky as a function of direction and frequency. Unlike standard cross-correlation methods, this approach preserves the amplitude, phase, and polarisation of the signal in every sky pixel. The resulting maps constitute a compact, minimally processed summary of the data from which all subsequent analyses -- characterisation of a stochastic background, searches for anisotropy, and identification of individual sources -- can be derived within a single unified framework. Our implementation is fully compatible with established pulsar timing data analysis methods. We validate the framework through a series of realistic simulations with varying array configurations, noise properties, and signal types. We demonstrate robust recovery of source amplitudes and sky locations across different scenarios, and discuss the impact of polarisation leakage, noise, and direction-dependent array sensitivity on the recovery of astrophysical signals.