from far-UV photons [@Blagorodnova2018; @Leloudas2019]; low-ionisation iron emission appearing shortly after maximum light [@Wevers2019b]; and recently the direct detection of double-peaked Balmer lines that match predicted disk profiles [@Short2020; @Hung2020]. Thus a critical question is to understand the nature and origin of the implied reprocessing layer. It has already been established that this cannot be simply the unbound debris stream, as the apparent cross-section is too low to intercept a significant fraction of the TDE flux [@Guillochon2014].

Inhibiting progress is the messy geometry of the debris. Colliding streams, inflowing and outflowing gas, and a viewing-angle dependence on both the broad-band [@Dai2018] and spectroscopic [@Nicholl2019] properties all contribute to a messy knot that must be untangled. One important clue comes from radio observations: although only a small (but growing) sample of TDEs have been detected in the radio [see recent review by @Alexander2020], in such cases we can measure the properties (energy, velocity, and density) of an outflow directly. In some TDEs this emission is from a relativistic jet [@Zauderer2011; @Bloom2011; @Burrows2011; @Cenko2012; @Mattila2018], which does not appear to be a common feature of TDEs, but other radio TDEs have launched sub-relativistic outflows [@vanvelzen2016; @Alexander2016; @Alexander2017].

A number of radio-quiet TDEs 