  Gravitational waves from compact binary coalescences provide a unique
laboratory to test properties of compact objects. As alternatives to the
ordinary black holes in general relativity, various exotic compact objects have
been proposed. Some of them have largely different values of the tidal
deformability and spin-induced quadrupole moment from those of black holes, and
their binaries could be distinguished from the binary black hole by using
gravitational waves emitted during their inspiral regime, excluding the highly
model-dependent merger and ringdown regimes. We reanalyze gravitational waves
from low-mass merger events in the GWTC-2, detected by the Advanced LIGO and
Advanced Virgo. Focusing on the influence of tidal deformability and
spin-induced quadrupole moment in the inspiral waveform, we provide
model-independent constraints on deviations from the standard binary black hole
case. We find that all events that we have analyzed are consistent with the
waveform of the binary black hole in general relativity. Bayesian model
selection shows that the hypothesis that the binary is composed of exotic
compact objects is disfavored by all events.
