Radiative penguin Bs decays at Belle

We report searches for the radiative penguin decays Bs0 → φγ and Bs0 → γγ based on a 23.6 fb-1 data sample collected with the Belle detector at the KEKB e+e- energy-asymmetric collider operating at the γ(5S) resonance. We obtain the first observation of a radiative penguin decay of the Bs0 meson in the Bs0 → φγ mode and we measure ss(Bs0-+ φγ) = (57-15+18 (stat) -17+12 (syst)) x 10-6. No significant Bs0 → γγ signal is observed and we set an upper limit at 90% confidence level of ss(Bs0 → γγ) < 8.6 x 10-6. These results are preliminary