Type Ib Supernova Master OT J120451.50+265946.6: Radio-emitting Shock with Inhomogeneities Crossing through a Dense Shell

We present radio observations of Type Ib supernova (SN) Master OT J120451.50+265946.6. Our low-frequency Giant Metrewave Radio Telescope (GMRT) data, taken when the SN was in the optically thick phase for observed frequencies, reveal inhomogeneities in the structure of the radio-emitting region. The high-frequency Karl G. Jansky Very Large Array data indicate that the shock is crossing through a dense shell between ∼47 and ∼87 days. The data ≥100 days onward are reasonably well fit with the inhomogeneous synchrotron self-absorption model. Our model predicts that the inhomogeneities should smooth out at late times. Low-frequency GMRT observations at late epochs will test this prediction. Our findings suggest the importance of obtaining well-sampled wide-band radio data in order to understand the intricate nature of the radio emission from young supernovae.