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Register a new userDips in the Diffuse Supernova Neutrino Background
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Added by
Sergio Palomares-Ruiz
Publication date
2014
fields
Physics
and research's language is
English
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Scalar (fermion) dark matter with mass in the MeV range coupled to ordinary neutrinos and another fermion (scalar) is motivated by scenarios that establish a link between radiatively generated neutrino masses and the dark matter relic density. With such a coupling, cosmic supernova neutrinos, on their way to us, could resonantly interact with the background dark matter particles, giving rise to a dip in their redshift-integrated spectra. Current and future neutrino detectors, such as Super-Kamiokande, LENA and Hyper-Kamiokande, could be able to detect this distortion.
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The Diffuse Supernova Neutrino Background (DSNB) in the MeV regime represents the cumulative cosmic neutrino emission, predominantly due to core collapse supernovae. We estimate the DSNB flux for different Star Formation Rate Density (SFRD) models. We find that the DSNB flux estimated using the SFRD derived from Fermi-LAT Collaboration et al. (2018) is significantly higher ($approx$ 32$%$) relative to the flux estimated using the SFRD from Madau & Fragos (2017). This depicts the sensitivity between the DSNB flux and the SFRD estimates which shows that future detection of the DSNB can be used as a valuable tool to constrain the SFRD.
LENA (Low Energy Neutrino Astronomy) has been proposed as a next generation 50 kt liquid scintillator detector. Its large target mass allows to search for the Diffuse Supernova Neutrino Background (DSNB), which was generated by the cumulative emissions of all core-collapse supernovae throughout the universe. Indistinguishable background from reactor and atmospheric electron antineutrinos limits the detection window to the energy range between 9.5 MeV and 25 MeV. Depending on the mean supernova neutrino energy, about 5 to 10 events per year are expected in this energy window. The background from neutral current reactions of atmospheric neutrinos surpasses the DSNB by more than one order magnitude, but can be suppressed by pulse shape discrimination. Assuming that the residual background is known with 5% uncertainty, the DSNB can be detected with 2 sigma significance after 10 years of data taking. In case that no hint for a signal is seen, current standard DSNB models would be ruled out with more than 90% C.L.
Supernovae are rare nearby, but they are not rare in the Universe, and all past core-collapse supernovae contributed to the Diffuse Supernova Neutrino Background (DSNB), for which the near-term detection prospects are very good. The Super-Kamiokande limit on the DSNB electron {it antineutrino} flux, $phi(E_ u > 19.3 {rm MeV}) < 1.2$ cm$^{-2}$ s$^{-1}$, is just above the range of recent theoretical predictions based on the measured star formation rate history. We show that the Sudbury Neutrino Observatory should be able to test the corresponding DSNB electron {it neutrino} flux with a sensitivity as low as $phi(22.5 < E_ u < 32.5 {rm MeV}) simeq 6 $ cm$^{-2}$ s$^{-1}$, improving the existing Mont Blanc limit by about three orders of magnitude. While conventional supernova models predict comparable electron neutrino and antineutrino fluxes, it is often considered that the first (and forward-directed) SN 1987A event in the Kamiokande-II detector should be attributed to electron-neutrino scattering with an electron, which would require a substantially enhanced electron neutrino flux. We show that with the required enhancements in either the burst or thermal phase $ u_e$ fluxes, the DSNB electron neutrino flux would generally be detectable in the Sudbury Neutrino Observatory. A direct experimental test could then resolve one of the enduring mysteries of SN 1987A: whether the first Kamiokande-II event reveals a serious misunderstanding of supernova physics, or was simply an unlikely statistical fluctuation. Thus the electron neutrino sensitivity of the Sudbury Neutrino Observatory is an important complement to the electron antineutrino sensitivity of Super-Kamiokande in the quest to understand the DSNB.
Sterile neutrinos with mass in the eV-scale and large mixings of order $theta_0simeq 0.1$ could explain some anomalies found in short-baseline neutrino oscillation data. Here, we revisit a neutrino portal scenario in which eV-scale sterile neutrinos have self-interactions via a new gauge vector boson $phi$. Their production in the early Universe via mixing with active neutrinos can be suppressed by the induced effective potential in the sterile sector. We study how different cosmological observations can constrain this model, in terms of the mass of the new gauge boson, $M_phi$, and its coupling to sterile neutrinos, $g_s$. Then, we explore how to probe part of the allowed parameter space of this particular model with future observations of the diffuse supernova neutrino background by the Hyper-Kamiokande and DUNE detectors. For $M_phi sim 5-10$~keV and $g_s sim 10^{-4}-10^{-2}$, as allowed by cosmological constraints, we find that interactions of diffuse supernova neutrinos with relic sterile neutrinos on their way to the Earth would result in significant dips in the neutrino spectrum which would produce unique features in the event spectra observed in these detectors.
Binary interactions, especially mass transfer and mergers, can strongly influence the evolution of massive stars and change their final properties and the occurrence of supernovae. Here, we investigate how binary interactions affect predictions of the diffuse flux of neutrinos. By performing stellar population syntheses including prescriptions for binary interactions, we show that the resulting detection rates of the diffuse supernova neutrino background is enhanced by 15%-20% compared to estimates without binary considerations. A source of significant uncertainty arises due to the presently sparse knowledge of the evolution of rapidly rotating carbon-oxygen cores, especially those created as a result of mergers near the white dwarf to core collapse boundary. The enhancement effect may be as small as a few percent if the effects of rotation in postmerger systems are neglected, or as large as 75% if trends are extrapolated. Our estimates serve to highlight that binary effects can be important.
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