  The merger of a super-massive binary black hole (SBBH) is one of the most
extreme events in the universe with a huge amount of energy released by
gravitational radiation. Although the characteristic gravitational wave (GW)
frequency around the merger event is far higher than the nHz regime optimal for
pulsar timing arrays (PTAs), nonlinear GW memory might be a critical smoking
gun of the merger event detectable with PTAs. In this paper, basic aspects of
this interesting observation are discussed for SBBHs, and the detection numbers
of their memory and inspiral GWs are estimated for ongoing and planned PTAs. We
find that the expected detection number would be smaller than unity for the
two-types of signals even with the Square Kilometer Array. We also provide
various scaling relations that would be useful to study detection probabilities
of GWs from individual SBBHs with PTAs.
