Although Galactic core-collapse supernovae (SNe) only happen a few times per century, every hour a vast number of explosions happen in the whole universe, emitting energy in the form of neutrinos, resulting in the diffuse supernova neutrino background (DSNB). The DSNB has not yet been detected, but Super-Kamiokande doped with gadolinium is expected to yield the first statistically significant observation within the next several years. Since the neutrinos produced at the core collapse undergo mixing during their propagation to Earth, the flavor content at detection is a test of oscillation physics. In this paper, we estimate the expected DSNB data at the DUNE, Hyper-K and JUNO experiments which when combined are sensitive to all different neutrino flavors. We determine how well the flavor content of the DSNB will be reconstructed in the future, for a Mikheyev-Smirnov-Wolfenstein (MSW) scenario as well as a neutrino decay scenario. A large fraction of the flavor space will be excluded, but the heavy-lepton neutrino flux remains a challenge.
Neutrinos from dense environments are connected to the longstanding open questions of how massive stars explode and what are the sites where $r$-process elements are made. Flavor evolution and neutrino properties can influence nucleosynthetic abundances. GW170817 has given indirect evidence for r-process elements in binary neutron star mergers. We discuss the impact of non-standard interactions in such sites. Nearby compact objects, strong gravitational fields are present. We discuss their influence upon neutrino decoherence in a wave packet treatment of neutrino propagation. We conclude by me…
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 unambiguo…
IceCube has measured a diffuse astrophysical flux of TeV-PeV neutrinos. The most plausible sources are unique high energy cosmic ray accelerators like hypernova remnants (HNRs) and remnants from gamma ray bursts in star-burst galaxies, which can produce primary cosmic rays with the required energies and abundance. In this case, however, ordinary supernova remnants (SNRs), which are far more abundant than HNRs, produce a comparable or larger neutrino flux in the ranges up to 100-150 TeV energies, implying a spectral break in the IceCube signal around these energies. The SNRs contribution in the…
We revisit the possibility that neutrinos undergo non-radiative decay. We investigate the potential to extract information on the neutrino lifetime-to-mass ratio from the diffuse supernova neutrino background. To this aim, we explicitly consider the current uncertainties on the core-collapse supernova rate and the fraction of failed supernovae. We present predictions in a full 3 neutrino framework in the absence and presence of neutrino non-radiative decay, for the Super-Kamiokande+Gd, the JUNO, the Hyper-Kamiokande, and the DUNE experiments, that should observe the diffuse supernova neutrino …
The diffuse supernova neutrino background (DSNB) is a powerful future tool to constrain core-collapse explosion mechanisms without observation of a nearby event, and the corresponding signal has been calculated for a variety of collapse models. For Supernova (SN) 1987A, a peculiar double neutrino burst was detected, but models for the double collapse have never been studied in the DSNB context. Here, we fill this gap and compare the DSNB signal expected in the Standard Collapse (SC) and the Double Collapse (DC) models in various future detectors, including Hyper-Kamiokande, JUNO, DUNE and the …
Sterile neutrinos with mass in the eV-scale and large mixings of order $θ_0\simeq 0.1$ 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 $ϕ$. 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, $M_ϕ$, and its coupling to s…
Unveiling Neutrino Nature with the Diffuse Supernova Background
Università del Salento（萨莱诺大学）；INFN-Istituto Nazionale di Fisica Nucleare, Sezione di Lecce（意大利国家核物理研究所莱切分部）；Niels Bohr International Academy and DARK, Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所及尼尔斯·玻尔国际学院与DARK）
While three flavors of "active" neutrinos are consistent with mixing angle results within error bars, there are anomalies may be hints of physics beyond the standard model that can accommodate a fourth mostly "sterile" neutrino species with an eV-scale mass and a mixing angle with active neutrinos of order $θ_0\simeq 0.1$. We describe a scenario with eV-scale sterile neutrinos that have self-interactions via a new gauge vector boson, a "secret" mediator $ϕ$. We show that their production in the early Universe via mixing with active neutrinos is consistent with Big Bang Nucleosynthesis and free…
I study the diffuse flux of electron antineutrinos from stellar collapses with direct black hole formation (failed supernovae). This flux is more energetic than that from successful supernovae, and therefore it might contribute substantially to the total diffuse flux above realistic detection thresholds. The total flux might be considerably higher than previously thought, and approach the sensitivity of SuperKamiokande. For more conservative values of the parameters, the flux from failed supernovae dominates for antineutrino energies above 30-45 MeV, with potential to give an observable spectr…
The cumulative emission of Axion-Like Particles (ALPs) from all past core-collapse supernovae (SNe) would lead to a diffuse flux with energies ${\mathcal O}(50)$ MeV. We use this to constrain ALPs featuring couplings to photons and to nucleons. ALPs coupled only to photons are produced in the SN core via the Primakoff process, and then converted into gamma rays in the Galactic magnetic field. We set a bound on $g_{aγ} \lesssim 5 \times 10^{-10}~{\rm GeV}^{-1}$ for $m_a \lesssim 10^{-11}~{\rm eV}$, using recent measurements of the diffuse gamma-ray flux observed by the Fermi-LAT telescope. Howe…
We investigate shock wave effects upon the diffuse supernova neutrino background using dynamic profiles taken from hydrodynamical simulations and calculating the neutrino evolution in three flavors with the S-matrix formalism. We show that the shock wave impact is significant and introduces modifications of the relic fluxes by about $20 \%$ and of the associated event rates at the level of $10-20 \%$. Such an effect is important since it is of the same order as the rate variation introduced when different oscillation scenarios (i.e. hierarchy or $θ_{13}$) are considered. In addition, due to th…
Fully understanding the average core-collapse supernova requires detecting the diffuse supernova neutrino background (DSNB) in all flavors. While the DSNB $\barν_e$ flux is near detection, and the DSNB $ν_e$ flux has a good upper limit and prospects for improvement, the DSNB $ν_x$ (each of $ν_μ, ν_τ, \barν_μ, \barν_τ$) flux has a poor limit and heretofore had no clear path for improved sensitivity. We show that a succession of xenon-based dark matter detectors -- XENON1T (completed), XENONnT/LUX-ZEPLIN (running), and DARWIN (proposed) -- can dramatically improve sensitivity to DSNB $ν_x$ the n…
The future detection and measurement of the diffuse neutrino supernova background will shed light on the rate of supernovae events in the Universe, the star formation rate and the neutrino spectrum from each supernova. Little has been said about what those measurements will tell us about the expansion history of the universe. The purpose of this article is to show that the detection of the diffuse supernova neutrino background will be a complementary tool for the study and possible discrimination of cosmological models. In particular, we study three different cosmological models: the $Λ$ Cold …
The detection of the diffuse supernova neutrino background (DSNB) will preciously contribute to gauge the properties of the core-collapse supernova population. We estimate the DSNB event rate in the next-generation neutrino detectors, Hyper-Kamiokande enriched with Gadolinium, JUNO, and DUNE. The determination of the supernova unknowns through the DSNB will be heavily driven by Hyper-Kamiokande, given its higher expected event rate, and complemented by DUNE that will help in reducing the parameters uncertainties. Meanwhile, JUNO will be sensitive to the DSNB signal over the largest energy rang…
The Diffuse Supernova Neutrino Background (DSNB) is the weak glow of MeV neutrinos and antineutrinos from distant core-collapse supernovae. The DSNB has not been detected yet, but the Super-Kamiokande (SK) 2003 upper limit on the electron antineutrino flux is close to predictions, now quite precise, based on astrophysical data. If SK is modified with dissolved gadolinium to reduce detector backgrounds and increase the energy range for analysis, then it should detect the DSNB at a rate of a few events per year, providing a new probe of supernova neutrino emission and the cosmic core-collapse ra…
I calculate the diffuse flux of electron antineutrinos from all supernovae using the information on the neutrino spectrum from SN987A and the information on the rate of supernovae from direct supernova observations. The interval of flux allowed at 99 % confidence level is 0.05 - 0.35 cm^-2 s ^-1 above the SuperKamiokande (SK) energy cut of 19.3 MeV. This result is at least a factor of 4 smaller than the current SK upper limit of 1.2 cm^-2 s ^-1, thus motivating the experimental efforts to lower the detection energy threshold or to upgrade to higher volumes. A Megaton water Cherenkov detector w…
In light of the latest IceCube data, we discuss the implications of the cosmic ray energy input from hypernovae and supernovae into the Universe, and their propagation in the hosting galaxy and galaxy clusters or groups. The magnetic confinement in these environments may lead to efficient $pp$ collisions, resulting in a diffuse neutrino spectrum extending from PeV down to 10 TeV energies, with a spectrum and flux level compatible with that recently reported by IceCube. If the diffuse 10 TeV neutrino background largely comes from such the CR reservoirs, the corresponding diffuse gamma-ray backg…
I review the physics of the Diffuse Supernova Neutrino flux (or Background, DSNB), in the context of future searches at the next generation of neutrino observatories. The theory of the DSNB is discussed in its fundamental elements, namely the cosmological rate of supernovae, neutrino production inside a core collapse supernova, redshift, and flavor oscillation effects. The current upper limits are also reviewed, and results are shown for the rates and energy distributions of the events expected at future liquid argon and liquid scintillator detectors of O(10) kt mass, and water Cherenkov detec…
The cumulative (anti)neutrino production from all core-collapse supernovae within our cosmic horizon gives rise to the diffuse supernova neutrino background (DSNB), which is on the verge of detectability. The observed flux depends on supernova physics, but also on the cosmic history of supernova explosions; currently, the cosmic supernova rate introduces a substantial (+/-40%) uncertainty, largely through its absolute normalization. However, a new class of wide-field, repeated-scan (synoptic) optical sky surveys is coming online, and will map the sky in the time domain with unprecedented depth…
The Dark Matter Diffused Supernova Neutrino Background
Arizona State University（亚利桑那州立大学）；Virginia Tech（弗吉尼亚理工大学）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构）；Massachusetts Institute of Technology（麻省理工学院）；Harvard University（哈佛大学）
Axion-like particles (ALPs) may be abundantly produced in core-collapse (CC) supernovae (SNe), hence the cumulative signal from all past SN events can create a diffuse flux peaked at energies of about 25~MeV. We improve upon the modeling of the ALPs flux by including a set of CC SN models with different progenitor masses, as well as the effects of failed CC SNe -- which yield the formation of black holes instead of explosions. Relying on the coupling strength of ALPs to photons and the related Primakoff process, the diffuse SN ALP flux is converted into gamma rays while traversing the magnetic…
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.
Non-standard neutrino interactions with a massive boson can produce the bosons in the core of core-collapse supernovae (SNe). After the emission of the bosons from the SN core, their subsequent decays into neutrinos can modify the SN neutrino flux. We show future observations of neutrinos from a next galactic SN in Super-Kamiokande (SK) and Hyper-Kamiokande (HK) can probe flavor-universal non-standard neutrino couplings to a light boson, improving the previous limit from the SN 1987A neutrino burst by several orders of magnitude. We also discuss sensitivity of the flavor-universal non-standard…
The advent of gadolinium-loaded Super-Kamiokande (SK-Gd) and of the soon-to-start JUNO liquid scintillator detector marks a substantial improvement in the global sensitivity for the Diffuse Supernova Neutrino Background (DSNB). The present article reviews the detector properties most relevant for the DSNB searches in both experiments and estimates the expected signal and background levels. Based on these inputs, we evaluate the sensitivity of both experiments individually and combined. Using a simplified statistical approach, we find that both SK-Gd and JUNO have the potential to reach $>$3$σ$…
The Hyper-Kamiokande (HyperK) experiment is expected to precisely measure the Diffuse Supernova Neutrino Background (DSNB). This requires that the backgrounds in the relevant energy range are well understood. One possible background that has not been considered thus far is the annihilation of low-mass dark matter (DM) to neutrinos. We conduct simulations of the DSNB signal and backgrounds in HyperK, and quantify the extent to which DM annihilation products can pollute the DSNB signal. We find that the presence of DM could affect the determination of the correct values of parameters of interest…
Star-forming and starburst galaxies are considered as one of the viable candidate sources of the high-energy cosmic neutrino background detected in IceCube. We revisit contributions of supernova remnants (SNRs) and hypernova remnants (HNRs) in such galaxies to the diffuse high-energy neutrino and gamma-ray backgrounds, in light of the latest Fermi data above 50GeV. We also take into account possible time dependent effects of the cosmic-ray (CR) acceleration during the SNR evolution. CRs accelerated by the SNR shocks can produce high-energy neutrinos up to $\sim100$ TeV energies, but CRs from H…
The diffuse cosmic supernova neutrino background (DSNB) is observational target of the gadolinium-loaded Super-Kamiokande (SK) detector and the forthcoming JUNO and Hyper-Kamiokande detectors. Current predictions are hampered by our still incomplete understanding of the supernova (SN) explosion mechanism and of the neutron star (NS) equation of state and maximum mass. In our comprehensive study we revisit this problem on grounds of the landscapes of successful and failed SN explosions obtained by Sukhbold et al. and Ertl et al. with parametrized one-dimensional neutrino engines for large sets …
Collective flavor oscillations driven by neutrino-neutrino self interaction inside core-collapse supernovae have now been shown to bring drastic changes in the resultant neutrino fluxes. This would in turn significantly affect the diffuse supernova neutrino background (DSNB), created by all core-collapse supernovae that have exploded in the past. In view of these collective effects, we re-analyze the potential of detecting the DSNB in currently running and planned large-scale detectors meant for detecting both electron neutrinos and antineutrinos. The next generation detectors should be able t…
An axion constraint from the diffuse supernova neutrino background indicated by Super-Kamiokande
Keio University（庆应义塾大学）；National Astronomical Observatory of Japan（日本国立天文台）；The Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）；Department of Astronomy, The University of Tokyo（东京大学天文学系）；Theory Center, IPNS, KEK（高能加速器研究机构理论中心）；Kavli IPMU (WPI), The University of Tokyo（东京大学加瓦利宇宙起源研究前沿中心）；National Institute of Technology (KOSEN), Numazu College（静冈县立沼津工业高等专门学校）
The XENON collaboration recently reported an excess of electron recoil events in the low energy region with a significance of around $3.3σ$. An explanation of this excess in terms of thermal dark matter seems challenging. We propose a scenario where dark matter in the Milky Way halo gets boosted as a result of scattering with the diffuse supernova neutrino background. This interaction can accelerate the dark-matter to semi-relativistic velocities, and this flux, in turn, can scatter with the electrons in the detector, thereby providing a much better fit to the data. We identify regions in the …
The relic neutrinos from old supernova explosions are among the most ancient neutrino fluxes within experimental reach. Thus, the diffuse supernova neutrino background (DSNB) could teach us if neutrino masses were different in the past (redshifts $z\lesssim 5$). Oscillations inside the supernova depend strongly on the neutrino mass-squared differences and the values of the mixing angles, rendering the DSNB energy spectrum sensitive to variations of these parameters. Considering a purely phenomenological parameterization of the neutrino masses as a function of redshift, we compute the expected …
We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5-10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10…
A large-scale neutrino observatory based on Water-based Liquid Scintillator (WbLS) will be excellently suited for a measurement of the Diffuse Supernova Neutrino Background (DSNB). The WbLS technique offers high signal efficiency and effective suppression of the otherwise overwhelming background from neutral-current interactions of atmospheric neutrinos. To illustrate this, we investigate the DSNB sensitivity for two configurations of the future Theia detector by developing the expected signal and background rejection efficiencies along a full analysis chain. Based on a statistical analysis of…
Collective flavor oscillations are known to bring multiple splits in the supernova (SN) neutrino and antineutrino spectra. These spectral splits depend not only on the mass hierarchy of the neutrinos but also on the initial relative flux composition. Observation of spectral splits in a future galactic supernova signal is expected to throw light on the mass hierarchy pattern of the neutrinos. However, since the Diffuse Supernova Neutrino Background (DSNB) comprises of a superposition of neutrino fluxes from all past supernovae, and since different supernovae are expected to have slightly differ…
In this article, we claim that axion-like particles (ALPs) with MeV masses can be produced with semi-relativistic velocities in core-collapse supernovae (SNe), generating a diffuse galactic flux. We show that these ALPs can be detected in neutrino water Cherenkov detectors via $a \, p \rightarrow p \, γ$ interactions. Using Super-Kamiokande data, we derive new constraints on the ALP parameter space, excluding a region spanning one order of magnitude in the ALP-proton coupling above cooling bounds for ALP masses in the range of $1-70$~MeV and ALP-proton couplings between $\sim 2\times10^{-5}-2\…
I address the question of what can be learned from the observation of the diffuse supernova neutrino flux in the precision phase, at next generation detectors of Megaton scale. An analytical study of the spectrum of the diffuse flux shows that, above realistic detection thresholds of 10 MeV or higher, the spectrum essentially reflects the exponential-times-polynomial structure of the original neutrino spectrum at the emission point. There is only a weak (tens of per cent) dependence on the power βdescribing the growth of the supernova rate with the redshift. Different original neutrino spectra…
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, $ϕ(E_ν> 19.3 {\rm MeV}) < 1.2$ 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 sensitivit…
We estimate the Diffuse Supernova Neutrino Background (DSNB) using the simulation results for neutron star-forming and black hole-forming stellar collapses from the Garching group. Scenarios with different distributions of black-hole forming collapses with the progenitor mass are discussed, and the uncertainty on the cosmological rate of collapses is included. The electron antineutrino component of the DSNB above 11 MeV of energy is found to be ~(1.4 - 3.7) cm^-2 s^-1; the contribution of black hole-forming collapses could dominate the flux above ~25 MeV. We calculate the potential of detectin…
The Universe is awash with tens-of-MeV neutrinos of all species coming from all past core-collapse supernovae. These have never been observed, but this state of affairs will change in the near future. In the less than ten years, the Super-Kamiokande experiment, loaded with gadolinium, is expected to collect dozens of events induced by the scattering of neutrinos from the diffuse supernova neutrino background (DSNB). Next-generation projects, including Hyper-Kamiokande and Theia, are expected to collect data samples with hundreds of DSNB events after a decade of running. Here, we study quantita…
We analyze the 1496 days of SuperKamiokande data to put limits on the nue, anti-nue, numu + nutau and anti-numu + anti-nutau components of the diffuse flux of supernova neutrinos, in different energy intervals and for different neutrino energy spectra. By considering the presence of only one component at a time, we find the following bounds at 90% C.L. and for neutrino energy E>19.3$ MeV: Phi_{nue}<73.3-154 cm^-2 s^-1, Phi_{anti-nue} <1.4-1.9 cm^-2 s^-1, Phi_{numu+nutau} <(1.0-1.4) 10^3 cm^-2 s^-1, and Phi_{anti-numu+ anti-nutau} <(1.3-1.8) 10^3 cm^-2 s^-1, where the intervals account for vary…
I derive an upper bound on the electron neutrino component of the diffuse supernova neutrino flux from the constraint on the antineutrino component at SuperKamiokande. The connection between antineutrino and neutrino channels is due to the similarity of the muon and tau neutrino and antineutrino fluxes produced in a supernova, and to the conversion of these species into electron neutrinos and antineutrinos inside the star. The limit on the electron neutrino flux is 5.5 cm^-2 s^-1 above 19.3 MeV of neutrino energy, and is stronger than the direct limit from Mont Blanc by three orders of magnitu…
The diffuse supernova neutrino background: an update with modern population synthesis and core-collapse simulations
Arizona State University（亚利桑那州立大学）；National Astronomical Observatory of Japan（日本国立天文台）；Shinshu University（信州大学）；The University of Tokyo（东京大学）；Institute of Science Tokyo（东京科学大学）；Virginia Tech（弗吉尼亚理工大学）；Fukuoka University（福冈大学）
