2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194414We investigate the quantum particle creation during the circularly symmetric collapse of a 2+1 dust cloud, for the cases when the cosmological constant is either zero or negative. We derive the Ford-Parker formula for the 2+1 case, which can be used to compute the radiated quantum flux in the geometric optics approximation. It is shown that no particles are created when the collapse ends in a naked singularity, unlike the 3+1 case. When the collapse ends in a BTZ black hole, we recover the expected Hawking radiation.15 pages, additional material added in Introduction and Discussion, conclusions unchanged, to appear in Physical Review DGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext