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The protagonists of cosmic reionization remain elusive. Faint star-forminggalaxies are leading candidates because they are numerous and may havesignificant ionizing photon escape fractions ($f_{esc}$). Here we update thispicture via an empirical model that successfully predicts latest observations(e.g., the drop in star-formation density at z>8). We generate an ionizingspectrum for each galaxy in our model and constrain $f_{esc}$ using latestmeasurements of the reionization timeline (e.g., Ly$\alpha$ damping of quasarsand galaxies at z>7). Assuming a constant $f_{esc}$, we find $M_{UV}$<-13.5galaxies need $f_{esc}=0.21^{+0.06}_{-0.04}$ to complete reionization. Theinferred IGM neutral fraction is [0.9, 0.5, 0.1] at z=[8.2, 6.8, 6.2]$\pm$0.2,i.e., the bulk of reionization transpires in 300 Myrs. Inspired by the emergentsample of Lyman Continuum (LyC) leakers that overwhelmingly displayshigher-than-average star-formation surface density ($\Sigma$), we propose amodel relating $f_{esc}$ to $\Sigma$ and find$f_{esc}\propto\Sigma^{0.4\pm0.1}$. Since $\Sigma$ falls by ~2.5 dex betweenz=8 and z=0, our model explains the humble upper limits on $f_{esc}$ at lowerredshifts and its required evolution to ~0.2 at z>6. Within this model,strikingly, <5% of galaxies with $M_{UV}$<-18 (the `oligarchs') account for>80% of the reionization budget. In fact, faint sources ($M_{UV}$>-16) must berelegated to a limited role to ensure high neutral fractions at z=7-8. Shallowfaint-end slopes of the UV luminosity function ($\alpha$>-2) and/or $f_{esc}$distributions skewed toward bright galaxies produce the required late and rapidreionization. We predict LyC leakers like COLA1 (z=6.6, $f_{esc}$~30%,$M_{UV}$=-21.5) become increasingly common towards z~6 and that the drivers ofreionization do not lie hidden across the faint-end of the luminosity function,but are already known to us. (abridged)

Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright, Star-Forming Galaxies with High Escape Fractions