Diffuse ultrahigh-energy gamma-ray emission from TeV halos

The LHAASO Collaboration has recently reported a measurement of the diffuse gamma-ray emission from the Galactic Plane at energies between 10 TeV and 1 PeV. While this emission is brighter than that expected from cosmic-ray interactions in the interstellar medium alone, we show that the intensity, spectrum, and morphology of this excess are in good agreement with that predicted from the ``TeV halos'' which surround the Milky Way's pulsar population. These results support the conclusion that TeV halos dominate the ultrahigh-energy sky, and that these objects convert ~5% of their total spindown power into very high and ultrahigh-energy photons.