Measuring the electron antineutrino component of the cosmic diffuse supernova
neutrino background (DSNB) is the next ambitious goal for low-energy neutrino
astronomy. The largest flux is expected in the lowest accessible energy bin.
However, for E < 15 MeV a possible signal can be mimicked by a solar electron
antineutrino flux that originates from the usual 8B neutrinos by spin-flavor
oscillations. We show that such an interpretation is possible within the
allowed range of neutrino electromagnetic transition moments and solar
turbulent field strengths and distributions. Therefore, an unambiguous
detection of the DSNB requires a significant number of events at E > 15 MeV.Comment: 4 pages, 1 figur