Memory remains undetected: Updates from the second LIGO/Virgo gravitational-wave transient catalog

Abstract

The LIGO and Virgo observatories have reported 39 new gravitational-wave detections during the first part of the third observation run, bringing the total to 50. Most of these new detections are consistent with binary black-hole coalescences, making them suitable targets to search for gravitational-wave memory, a nonlinear effect of general relativity. We extend a method developed in previous publications to analyze these events to determine a Bayes factor comparing the memory hypothesis to the no-memory hypothesis. Specifically, we calculate Bayes factors using two waveform models with higher-order modes that allow us to analyze events with extreme mass ratios and precessing spins, both of which have not been possible before. Depending on the waveform model, we find a combined $\mathrm{ln}{\mathrm{BF}}_{\mathrm{mem}}=0.024$ or $\mathrm{ln}{\mathrm{BF}}_{\mathrm{mem}}=0.049$ in favor of memory. This result is consistent with recent predictions that indicate $\mathcal{O}(2000)$ binary black-hole detections will be required to confidently establish the presence or absence of memory.