Centrality dependence of direct photons in Au plus Au collisions at √SNN=200 GeV -: art. no. 041902

We calculate the spectra of high-energy photons emitted in relativistic Au + Au collisions for various centralities and compare to data recently collected at the Relativistic Heavy Ion Collider by the PHENIX Collaboration. Our results for photons from primary hard scatterings and photons from interactions of jets with the medium are consistent with the measurements of neutral pion and direct photon production in p + p collisions and give a good description of direct photon spectra measured in Au + Au collisions. The contribution of photons from jet-to-photon conversion in the medium can be as large as the photon yield from hard scatterings in the momentum range p(T) approximate to 2-6 GeV/c. We show that this novel mechanism is not ruled out by any existing data.