FrankenStat I: a New Approach to Pulsar Timing Array Data Combination

TL;DR

FrankenStat is a novel, efficient method for combining pulsar timing array data that maintains sensitivity and accuracy while significantly reducing computation time, aiding gravitational wave background detection.

Contribution

It introduces FrankenStat, a new approach extending PTA data combination techniques beyond detection statistics to a full, efficient, and accurate data integration method.

Findings

Demonstrated efficacy on simulated data

Achieves sensitivity comparable to traditional methods

Completes data combination in minutes

Abstract

In 2023, after more than two decades of searching, pulsar timing array (PTA) collaborations around the world announced evidence for a stochastic gravitational wave background. It was quickly followed by work from the International Pulsar Timing Array (IPTA), demonstrating that the results of regional collaborations were consistent with each other. The combination of these datasets is still ongoing and represents a significant investment of time and expertise. In that IPTA comparison, authors of this letter combined the separate datasets in the standard PTA optimal detection statistic for cross-correlations incoherently, that is, the data was combined without fitting a merged timing model across all PTA datasets, treating datasets of the same pulsar as independent, and neglecting the "same pulsar, different datasets" cross-correlations. This work refines that method by extending its core ideas beyond detection statistics and into a full, general data-combination method. We have demonstrated its efficacy and extreme efficiency on simulated data. This new method, \textit{FrankenStat}, is very similar in sensitivity and parameter-constraining power to traditional data combination methods while completing the full data combination in just a few minutes.