The Dark Matter Diffused Supernova Neutrino Background

TL;DR

This work investigates dark matter–neutrino interactions at MeV energies by introducing the Dark Matter Diffused Supernova Neutrino Background (DMDSNB), a time-delayed, galactically sourced neutrino flux produced when SN neutrinos scatter off Milky Way dark matter. The authors build a modeling framework combining the Milky Way DM density (using an NFW profile), the Galactic SN rate, and SN neutrino spectra to predict the DMDSNB, and then constrain the cross section per mass $\sigma_{\mathrm{DM}-\nu}/m_{\mathrm{DM}}$ using SN1987A data and Super-Kamiokande DSNB limits. They derive the strongest MeV-energy bound to date: $\sigma_{\mathrm{DM}-\nu}/m_{\mathrm{DM}} \lesssim 2.4\times 10^{-24}\ \mathrm{cm^{2}\,GeV^{-1}}$ for $m_{\mathrm{DM}} \gtrsim 1$ GeV, with the DMDSNB flux remaining nearly constant in time for these masses; SN1987A attenuation and time-delayed bounds remain weaker by factors of $\sim$10–$a$ few thousand. The study also discusses how the DMDSNB could be distinguished from the ordinary DSNB via spectral and temporal differences and highlights the potential for stronger bounds as DSNB measurements improve, as well as possible extensions such as DM spikes near the Galactic center. Overall, this work provides a novel astrophysical probe of dark matter–neutrino interactions and a pathway to tighter constraints with future diffuse neutrino measurements.

Abstract

We consider neutrinos scattering off Milky Way dark matter and the impact of this scattering on supernovae neutrinos. This can take the form of attenuation on the initial flux of neutrinos and a time-delayed flux of scattered neutrinos. Considering dark matter masses above 100 MeV and past Milky Way supernovae, we find this time-delayed flux is nearly constant in time. We call this flux the Dark Matter Diffused Supernova Neutrino Background (DMDSNB), and use Super-K limits on the Diffuse Supernova Neutrino Background (DSNB) flux to set limits on the dark matter-neutrino scattering cross section. We find $σ_{\rm DM-ν}/m_{\rm DM} \lesssim 2.4 \times 10^{-24} \mathrm{cm^2}$/GeV for $m_{\rm DM} \gtrsim 1$ GeV, which is the strongest bound to date on dark matter-neutrino scatterings at MeV energies, and stronger than bounds set from SN1987A neutrino attenuation by an order of magnitude. We end by discussing how the DMDSNB could be distinguished from the DSNB.

Figures (8)

• Figure 1: Characteristic neutrino delay time as a function of dark matter mass for supernova positions SN 1987A, (-1,0,0) kpc, and (8.5,0,0) kpc (note that the last point is $-\overrightarrow{r_{\oplus}}$). We have fixed the scattering cross section $\sigma_{\mathrm{DM}-\nu}/m_{\mathrm{DM}}$ to $10^{-26} \, \mathrm{cm^2} \, \mathrm{GeV^{-1}}$ which makes the optical depth between the supernovae and Earth is much less than 1. Furthermore, scattering is taken to be isotropic in the COM frame. We note that the value saturates at $m_{\mathrm{DM}} \sim 1$ GeV, at a value of $\mathcal{O}(10^{4})$ years (or $\mathcal{O}(1)$ kpc). This saturation value seems to have a slight dependence on the supernova location.
• Figure 2: Left: Excluded value of $\sigma_{\mathrm{DM}-\nu}$ as a function of $m_{\mathrm{DM}}$ from SN 1987A attenuation, SN 1987A time-delayed neutrinos at Super-K, and the DMDSNB at Super-K. Note that for dark matter masses below 100 MeV, the DMDSNB exclusions are dotted, as we do not expect the fluxes to be constant in time (see App. \ref{['sec:Stochastic']}). Right: The same exclusions expressed as a $\sigma_{\mathrm{DM}-\nu}/m_{\mathrm{DM}}$ ratio.
• Figure 3: Left: Summary of bounds on dark matter-neutrino scatterings across neutrino energy. The bounds derived in this work from SN1987A and from the Dark Matter Diffused Supernova Neutrino Background (DMDSNB) are shown as blue and green triangles, respectively. Furthermore, we show in green lines the strength of our limits at different neutrino energies, for different phenomenological dependences of the cross section with neutrino energy. Our constraints are compared to cosmological hints and bounds (in orange and red) Crumrine:2024sdnHooper:2021rjc, and to bounds from high-energy neutrinos (in brown and black) Arguelles:2017atbGonzaloTXSAtten. Right: Summary of bounds on the dark matter-neutrino scattering cross section from supernovae. Our bounds on attenuation effects from SN1987A (blue), time delays (red), and the DMDSNB (green) are compared with previous bounds on attenuation effects in SN1987A (light blue) where they did not use an NFW profile nor did they consider the dark matter enhancement in the LMC Mangano:2006mp, and with bounds from the impact of dark matter-neutrino scatterings on dwarf spheroidals Heston:2024ljf.
• Figure 4: Flux vs observed neutrino energy for different scenarios. Left: The blue line considers only the DSNB contribution calculated using Eq. \ref{['eq-DSNB-Calc']}. The red (green) lines show the combined flux from the DSNB and DMDSNB with dark matter of $m_{\mathrm{DM}} =$1 GeV and $\sigma_{\mathrm{DM}-\nu} = 10^{-25} \,(10^{-24})\, \mathrm{cm^2}$. We see that especially at higher energies, the expected fluxes of cases with and without the DMDSNB differ. The grey shaded region indicates the range of theory predictions (see SKRunIVDSNB and references therein). Right: The neutrino flux solely from the DMDSNB for dark matter of different masses. We fix the ratio $\sigma_{\mathrm{DM}-\nu}/m_{\mathrm{DM}} = 10^{-25}$ cm$^2$ GeV$^{-1}$.
• Figure 5: Differential flux of the DMDSNB as observed from Earth. The point of $x=y=0^{\circ}$ is directed towards the galactic center. The x-y asymmetry is from the supernova distribution extending further in the radial direction than the horizontal, and the strong focus towards the central point due to the high dark matter density near the galactic center.