The Energy Ceiling of Hawking Radiation Implied by a Finite Remnant Temperature

The ceiling temperature of 1.417e+12 kelvin gives a characteristic energy of 1.221e-01 giga-electronvolts and a spectral peak at 3.443e-01 giga-electronvolts, corresponding to a wavelength of 3.601e-15 metres. The endpoint therefore sits in the high-energy gamma-ray band, some nineteen orders of magnitude below the Planck energy. Instruments built for that band exist and have surveyed the sky, so an endpoint of this kind is, unusually for quantum-gravity phenomenology, an observationally addressable statement. Addressable is not the same as easy: the endpoint appears only in the final stage of a hole that is expiring now, and predicted burst rates are a separate, population-dependent question. Computed from stated assumptions, not measured.