Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. III. Late-time Jet Energetics and a Deviation from Equipartition

Understand

We present continued radio and X-ray observations of the relativistic tidal disruption event Swift J164449.3+573451 extending to $\delta t \approx 2000$ d after discovery.

• The radio data were obtained with the VLA as part of a long-term program to monitor the energy and dynamical evolution of the relativistic jet and to characterize the parsec-scale environment around a previously dormant supermassive black hole.
• We combine these data with $\textit{Chandra}$ X-ray observations and demonstrate that the X-ray emission following the sharp decline at $\delta t \approx 500$ d is due to the forward shock.
• Using the X-ray data, in conjunction with optical/NIR data, we constrain the synchrotron cooling frequency and the microphysical properties of the outflow for the first time.