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We report here radio follow-up observations of the optical Tidal DisruptionEvent (TDE) AT 2019azh. Previously reported X-ray observations of this TDEshowed variability at early times and a dramatic increase in luminosity, by afactor of $\sim 10$, about 8 months after optical discovery. The X-ray emissionis mainly dominated by intermediate hard--soft X-rays and is exceptionally softaround the X-ray peak, which is $L_X \sim 10^{43} \rm \, erg \, s^{-1}$. Thehigh cadence $15.5$ GHz observations reported here show an early rise in radioemission followed by an approximately constant light curve, and a late-timeflare. This flare starts roughly at the time of the observed X-ray peakluminosity and reaches its peak about $110$ days after the peak in the X-ray,and a year after optical discovery. The radio flare peaks at $\nu L_{\nu} \sim10^{38} \rm \, erg \, s^{-1}$, a factor of two higher than the emissionpreceding the flare. In light of the late-time radio and X-ray flares, and theX-ray spectral evolution, we speculate a possible transition in the accretionstate of this TDE, similar to the observed behavior in black hole X-raybinaries. We compare the radio properties of AT 2019azh to other known TDEs,and focus on the similarities to the late time radio flare of the TDEASASSN-15oi.

A Late-Time Radio Flare following a Possible Transition in Accretion State in the Tidal Disruption Event AT 2019azh