Proc. Neutrino Astrophysics - MPP Theory Group

Figure 3: Energy spectra of the supernova relic neutrino background (SRN) for various cosmological
models. All lines represent the differential number flux of electron antineutrinos
(¯νe’s). The thick lines show the SRN spectrum for a low-density, flat universe with Ω0 = 0.2,
λ0 = 0.8, and three different values of the Hubble constant; h = 0.5 (bottom line), h = 0.8
(middle line), and h = 1.0 (top line). The dashed line shows the SRN spectrum for a lowdensity,
open universe with Ω0 = 0.2, λ0 = 0.0, and h = 0.8, and the dot-dashed line for an
Einstein-de Sitter universe with Ω0 = 1.0, λ0 = 0.0, and h = 0.5. The S1 model is used to
represent the evolution of spiral galaxies, and the standard SFR model for elliptical galaxies.
The epoch of galaxy formation is set to be zF = 5. For an illustrative purpose of comparison,
two SRN spectra based on a model with a constant supernova rate are also shown by the
dotted lines. The supernova rates of the two curves are chosen as follows. In the case of the
upper curve, the time-integrated number of supernovae is the same with that of our standard
model (thick, middle line), and in the case of the lower curve, the present rate of supernovae
is the same with that of the standard model.
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