Illumination of a Planet by a Black Hole Moon as a Technological Signature

I show that Hawking radiation from a mini black hole with a mass of ∼10¹¹ g in a low orbit around an otherwise frozen rogue planet, can supply the energy needs of a civilization on the surface of the planet. Maintaining this furnace for more than a few years requires a modest accretion rate of ∼2 kg s^‑1. The associated technosignature is detectable as a gamma-ray source occulted by a warm planet every 1–2 hr, with no stellar-mass companion.