Effects of annihilation with low-energy neutrinos on high-energy neutrinos from binary neutron star mergers and rare core-collapse supernovae

We explore the possibility that high-energy (HE) neutrinos produced from choked jets can be annihilated with low-energy neutrinos emitted from the accretion disk around a black hole in binary neutron star mergers and rare core-collapse supernovae. For HE neutrinos produced close to the stellar center ($\lesssim {10}^9–{10}^{12}\mathrm{cm}$), we find that the emerging all-flavor spectrum for neutrinos of $E\gtrsim 0.1–1\mathrm{PeV}$ could be modified by a factor $E^{-n}$ with $n\gtrsim 0.4–0.5$ under realistic conditions. Flavor evolution of low-energy neutrinos does not affect this result but can change the emerging flavor composition of HE neutrinos. As a consequence, the above annihilation effect may need to be considered for HE neutrinos produced from choked jets at small radii. We briefly discuss the annihilation effects for different HE neutrino production models and point out that such effects could be tested through precise measurements of the diffuse neutrino spectrum and flavor composition.

Figure 1

Sketch of interaction between HE ${\nu }_{\alpha }$ and LE ${\overline{\nu }}_{\beta }$.

Figure 2

The fit of $⟨P_{{\nu }_{\mu }}(E)⟩$ to Eq. (8) (solid lines), with $*$ representing the numerically calculated $⟨P_{{\nu }_{\mu }}⟩$ from Eq. (7) at specific values of $E$ for the NO scenario of LE neutrino flavor evolution. For cases A, B, and C, $g_{\mathrm{\Gamma }}({\theta }_0)$ is used, and $(T_{\nu ,\mathrm{MeV}},R_{\mathrm{sh},9},{\mathrm{\Gamma }}_{\mathrm{sh}})=(3,10,5)$, (6,10,5), and (8,3,3), respectively. For cases D, E, and F, $g_{\theta }({\theta }_0)$ is used, and $(T_{\nu ,\mathrm{MeV}},R_{\mathrm{sh},9},{\theta }_{\mathrm{sh}})=(6,100,10°)$, $(6,100,20°)$, and $(6,100,30°)$, respectively.

Figure 3

Fitting parameters $E_0$ and $n$ as functions of $\eta$ for $⟨P_{{\nu }_{\mu }}(E)⟩$ in the NO scenario of LE neutrino flavor evolution. Left panel: the three trends for $E_0$ and $n$ are for ${\mathrm{\Gamma }}_{\mathrm{sh}}=10$ (blue), 5 (green), and 3 (red), respectively. Right panel: the three trends are for ${\theta }_{\mathrm{sh}}=10°$ (red), 20° (green), and 30° (blue), respectively. The dashed line corresponds to $E_0=0.1\mathrm{PeV}$.

Figure 4

Left panel: (a) effects of $\nu \overline{\nu }$ annihilation on $\varphi /{\varphi }^{(0)}$ for $(T_{\nu ,\mathrm{MeV}},R_{\mathrm{sh},9},{\mathrm{\Gamma }}_{\mathrm{sh}})=(3,10,5)$, (6,10,5), and (8,3,3) corresponding to cases A, B, and C, respectively. (b) Effects of $\nu \overline{\nu }$ annihilation on $R_{\mu /e}$ for case B. (c) Same as (b) but for case C. Right panel: (d) effects of $\nu \overline{\nu }$ annihilation on $\varphi /{\varphi }^{(0)}$ for $(T_{\nu ,\mathrm{MeV}},R_{\mathrm{sh},9},{\theta }_{\mathrm{sh}})=(6,100,10°)$, $(6,100,20°)$, and $(6,100,30°)$ corresponding to cases D, E, and F, respectively. (e) Effects of $\nu \overline{\nu }$ annihilation on $R_{\mu /e}$ for case E. (f) Same as (e) but for case F. In each case, the curves from top to bottom are for LE neutrino flavor evolution scenarios NE, NO, IO, and EE, respectively.