Upper limits on the diffuse supernovaneutrino flux from theSuperKamiokande data

We analyze the 1496 days of SuperKamiokande data to put limits on the ν_e, ν_μ+ν_τ and components of the diffuse flux of supernova neutrinos, in different energy intervals and for different neutrino energy spectra. By considering the presence of only one component at a time, we find the following bounds at 90% CL and for neutrino energy E>19.3MeV: Φ_νe<73.3-154cm^-2s ^-1, Φ_νμ+ν_τ<(1.0-1.4) × 10³cm^-2s^-1 and , where the intervals account for varying the neutrino spectrum. In the interval E = 22.9-36.9MeV, we find Φ_νe<39-54cm^-2s^-1, which improves on the existing limit from SNO in the same energy window. Our results for ν_μ+ν_τ and improve by about four orders of magnitude the previous best constraints from LSD.