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The tidal disruption event AT2019dsg was observed from radio to X-rays andwas possibly accompanied by a high-energy neutrino. Previous interpretationshave focused on continued injection by a central engine as the source of energyfor radio emission. We show that continuous energy injection is unnecessary;the radio data can be explained by a single ejection of plasma that suppliesall the energy needed. To support this assertion, we analyze the synchrotronself-absorbed spectra in terms of the equipartition model. Similar to previousanalyses, we find that the energy in the radio-emitting region increasesapproximately $\propto t^{0.7}$ and the lengthscale of this region grows$\propto t$ at a rate $\simeq0.06c$. This event resembles the earliest stage ofa supernova remnant: because the ejected mass is much greater than the shockedexternal mass, its velocity remains unchanged, while the energy in shocked gasgrows with time. The radio-emitting material gains energy from the outflow, notcontinuing energy injection by the central object. Although energy injectionfrom an accreting BH cannot be completely excluded, the energy injection rateis very different from the fallback luminosity, and maintaining constantoutflow velocity requires fine-tuning demanding further physical explanation.If the neutrino association is real, the energy injection needed is muchgreater than for the radio emission, suggesting that the detected neutrino didnot arise from the radio-emitting region.

What powers the radio emission in TDE AT2019dsg: a long-lived jet or the disruption itself?