  We show that the recently reported cosmic gravitational wave background by
the NANOGrav 15-year collaboration may be the result of resonant particle
creation during inflation. For the appropriate amplitude and particle mass an
enhancement of the primordial scalar power spectrum could induce Secondary
Induced Gravitational Waves (SIGW) which will appear on a scale corresponding
to the frequency of the NANOGrav detection. Since the resonant creation will
have an effect comparable to that of a delta function increment as studied by
the NANOGrav 15-year collaboration, our study indicates that the low-frequency
Pulsar Timing Array (PTA) data could reveal the aspects of the physics during
inflation through the detection of a cosmic background of Gravitational Waves
(GW).
