Are PTA measurements sensitive to gravitational wave non-Gaussianities?

TL;DR

This paper demonstrates that current PTA data analysis methods cannot reliably detect non-Gaussian features in gravitational wave backgrounds without strong assumptions, even in idealized conditions.

Contribution

It shows that statistical tests on PTA data are insensitive to non-Gaussianities without specific model assumptions, challenging their use as discriminators.

Findings

PTA data analysis cannot distinguish Gaussian from non-Gaussian GWBs in idealized setups.

Sensitivity to non-Gaussian features is lost after data decorrelation.

Model-agnostic tests are insufficient for detecting non-Gaussianities in PTA data.

Abstract

Observing non-Gaussianity in the timing residuals of Pulsar Timing Arrays (PTAs) has recently attracted attention as a potential discriminator between astrophysical and cosmological origins of the observed Gravitational Wave (GW) signal. In this work, we show that even in an idealized signal-dominated setup, after decorrelating data to avoid spurious detections, statistical tests applied to PTA data cannot distinguish between Gaussian and non-Gaussian GWBs in a model-agnostic way. In particular, without making strong assumptions on the GW spectrum or the properties of the population, the sensitivity to any distinctive non-Gaussian feature is washed out.