Resonant scattering of light in a near-black-hole metric
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We show that low-energy photon scattering from a body with radius R slightly larger than its Schwarzschild radius r s resembles black-hole absorption. This absorption occurs via capture resulting in one of the many long-lived, densely packed resonances that populate the continuum. The lifetimes and density of these meta-stable states tend to infinity in the limit r s →R. We determine the energy-averaged cross section for particle capture into these resonances and show that it is equal to the absorption cross section for a Schwarzschild black hole. Thus a non-singular static metric may trap photons for arbitrarily long times, making it appear completely ‘black’ before the actual formation of a black hole.
KeywordsAbsorption Cross Section Resonance Width Exterior Region Coulomb Phase Shift Small Energy Interval
We thank G.F. Gribakin for useful discussions. This work is supported by the Australian Research Council.