Searching for gravitational wave memory bursts with the Parkes Pulsar Timing Array

TL;DR

This paper develops a search algorithm for gravitational wave memory bursts using pulsar timing data, applies it to six years of observations, finds no events, and sets upper bounds on event rates.

Contribution

It introduces a novel algorithm for detecting gravitational wave memory bursts in pulsar timing data and applies it to real data, establishing new upper limits.

Findings

No gravitational wave memory events detected

Set upper bounds on event rates

Non-detection aligns with black hole coalescence models

Abstract

Anisotropic bursts of gravitational radiation produced by events such as super-massive black hole mergers leave permanent imprints on space. Such gravitational wave "memory" (GWM) signals are, in principle, detectable through pulsar timing as sudden changes in the apparent pulse frequency of a pulsar. If an array of pulsars is monitored as a GWM signal passes over the Earth, the pulsars would simultaneously appear to change pulse frequency by an amount that varies with their sky position in a quadrupolar fashion. Here we describe a search algorithm for such events and apply the algorithm to approximately six years of data from the Parkes Pulsar Timing Array. We find no GWM events and set an upper bound on the rate for events which could have been detected. We show, using simple models of black hole coalescence rates, that this non-detection is not unexpected.