  Gravitational wave echo signals have been proposed as evidence for the
modification of the spacetime structure near the classical event horizon. These
signals are expected to occur after the mergers of compact binaries as a
sequence of weak pulse-like signals. Some studies have shown evidence of the
echo signals from several binary black hole merger events. On the other hand,
the other studies have shown the low significance of such signals from various
events in the first, second and third observing runs (O1, O2 and O3). Our
previous study also shows the low significance of echo signals from events in
O1 and O2, though, we observe that more than half of the events have p-value
smaller than 0.1 when the simply modeled waveform is used for the analysis.
Since there are only nine events appropriate for this analysis in O1 and O2, it
is necessary to analyze more events to evaluate the significance statistically.
In this study, we search for echo signals from binary black hole events
observed during O3 operated by LIGO, Virgo and KAGRA collaborations. We perform
the template-based search by using two different models for echo signal
templates: simply modeled one and physically motivated one. Our results show
that the distributions of p-values for all events analyzed in this study are
consistent with the noise distribution. This means that no significant echo
signals are found for both models from O3 events.
