The NANOGrav 15-year Data Set: Search for Gravitational Wave Memory

TL;DR

This study searches for nonlinear gravitational wave memory in 15 years of pulsar timing data, finds no significant signals, and sets upper limits on potential memory event strains, highlighting noise challenges.

Contribution

First comprehensive search for gravitational wave memory in 15-year NANOGrav data, establishing upper limits and analyzing noise effects.

Findings

No significant gravitational wave memory signals detected.

Upper limits vary by sky location and epoch.

Increase in common red noise affects constraint strength.

Abstract

We present the results of a search for nonlinear gravitational wave memory in the NANOGrav 15-year data set. We find no significant evidence for memory signals in the dataset, with a maximum Bayes factor of 3.1 in favor of a model including memory. We therefore place upper limits on the strain of potential gravitational wave memory events as a function of sky location and observing epoch. We find upper limits that are not always more constraining than previous NANOGrav results. We show that it is likely due to the increase in common red noise between the 12.5-year and 15-year NANOGrav datasets.