We study temperature dependence of the topological susceptibility with the Wilson fermion.
We have two major interest in this paper.
One is a comparison of gluonic and fermionic definition of the topological susceptibility.
Two definitions are related by the chiral Ward-Takahashi identity but their coincidence is
highly non-trivial for the Wilson fermion.
By applying the gradient flow both for the gauge and quark field we find a good agreement of
these two measurements.
The other is a verification of a prediction of the dilute instanton gas approximation at low temperature
region Tpc\simleT\simle1.5Tpc, for which
we confirm the prediction that the topological susceptibility decays with power
χt∝(T/Tpc)−8 for three flavors QCD.
