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We use a semi-analytic model to explore the potential impact of a brief andviolent period of radio-loud accretion onto black-holes (The Radio Scream)during the Cosmic Dawn on the HI hyperfine 21 cm signal. We find that radioemission from super-massive black hole seeds can impact the global 21 cm signalat the level of tens to hundreds of percent provided that they were as radioloud as $z\approx1$ black holes and obscured by gas with column depths of$N_\text{H}\gtrsim 10^{23}$ cm$^{-2}$. We determine plausible sets ofparameters that reproduce some of the striking features of the EDGES absorptionfeature including its depth, timing, and side steepness while producingradio/X-ray backgrounds and source counts that are consistent with publishedlimits. Scenarios yielding a dramatic 21 cm signature also predict largepopulations of $\sim \mu$Jy point sources that will be detectable in futuredeep surveys from the Square Kilometer Array (SKA). Thus, 21 cm measurements,complemented by deep point source surveys, have the potential to constrainoptimistic scenarios where super-massive black-hole progenitors wereradio-loud.

The Radio Scream from Black Holes at Cosmic Dawn: A Semi-Analytic Model for the Impact of Radio Loud Black-Holes on the 21 cm Global Signal