TeV-PeV neutrinos over the atmospheric background: originating from two groups of sources?

In addition to the two ~1 PeV neutrinos, the IceCube Collaboration recently reported a detection of 26 neutrino candidates at energies from 30 TeV to 250 TeV, implying a confidence level of 4.3\sigma over the atmospheric background. We suggest that these TeV-PeV non-atmospheric neutrinos may originate from two groups of sources, motivated by the non-detection of neutrinos in the energy range 250 TeV- 1 PeV in current data. If intrinsic, the non-detection of 250 TeV-1 PeV neutrinos disfavors the single power-law spectrum model for the TeV-PeV non-atmospheric neutrinos at a confidence level of ~ 2\sigma. We then interpret the current neutrino data with a two-component spectrum model. One has a flat spectrum with a cutoff at the energy ~ 250 TeV and the other has a sharp peak at ~1 PeV. The former is likely via pp collision while the latter may be generated by the photomeson interaction.