We demonstrate a multipole expansion method to calculate collective neutrino oscillations in supernovae using the neutrino bulb model. We show that it is much more efficient to solve multi-angle neutrino oscillations in multipole basis than in angle basis. The multipole expansion method also provides interesting insights into multi-angle calculations that were accomplished previously in angle basis.
Recent theoretical work indicates that the neutrino radiation in core-collapse supernovae may be susceptible to flavor instabilities that set in far behind the shock, grow extremely rapidly, and have the potential to profoundly affect supernova dynamics and composition. Here we analyze the nonlinear collective oscillations that are prefigured by these instabilities. We demonstrate that a zero-crossing in $n_{ν_e} - n_{\barν_e}$ as a function of propagation angle is not sufficient to generate instability. Our analysis accounts for this fact and allows us to formulate complementary criteria. Usi…
In this paper, we explore the effects of neutrino flavor oscillations on supernova nucleosynthesis and on the neutrino signals. Our study is based on detailed information about the neutrino spectra and their time evolution from a spherically-symmetric supernova model for an 18 M progenitor. We find that collective neutrino oscillations are not only sensitive to the detailed neutrino energy and angular distributions at emission, but also to the time evolution of both the neutrino spectra and the electron density profile. We apply the results of neutrino oscillations to study the impact on super…
Fast flavor conversions of supernova neutrinos, possible near the neutrinosphere, depends on an interesting interplay of collisions and neutrino oscillations. Contrary to naive expectations, the rate of self-induced neutrino oscillations, due to neutrino-neutrino forward scattering, comfortably exceeds the rate of collisions even deep inside the supernova core. Consistently accounting for collisions and oscillations, we present the first calculations to show that collisions can create the conditions for fast flavor conversions of neutrinos, but oscillations can continue without significant dam…
We study the effect of Majorana transition magnetic moments on the flavor evolution of neutrinos and antineutrinos inside the core of Type-II supernova explosions. We find non-trivial collective oscillation effects relating neutrinos and antineutrinos of different flavors, even if one restricts the discussion to Majorana transition electromagnetic moment values that are not much larger than those expected from standard model interactions and nonzero neutrino Majorana masses. This appears to be, to the best of our knowledge, the only potentially observable phenomenon sensitive to such small val…
We investigate the collective neutrino oscillations under the three flavor multi-angle approximation in a spherically symmetric simulation of failed supernovae. A failed supernova emits high neutrino fluxes in a short time, while intense accretion proceeds with high electron density enough to experience re-collapse into a black hole. Our results show that matter-induced effects completely dominate over neutrino self-interaction effects and multi-angle matter suppression occurs at all time snapshots we studied. These facts suggest us that only MSW resonances affect the neutrino flavor conversio…
We give a very brief overview of collective effects in neutrino oscillations in core collapse supernovae where refractive effects of neutrinos on themselves can considerably modify flavor oscillations, with possible repercussions for future supernova neutrino detection. We discuss synchronized and bipolar oscillations, the role of energy and angular neutrino modes, as well as three-flavor effects. We close with a short summary and some open questions.
It has been realized that the shock wave effects play an important role in neutrino oscillations during the supernova explosion. In recent years, with the development of simulations about supernova explosion, we have a better understanding about the density profiles and the shock waves in supernovae than before. It has been shown that the appearance of shock waves not only varies with time, but is also affected by the mass of the supernova. When the mass of the supernova happens to be in a certain range (e.g. it equals 10.8 times the mass of the sun), there might be a reverse shock wave, anoth…
Axionlike-particles (ALPs) are one promising type of dark matter candidate particle that may generate detectable effects on $γ$-ray spectra other than the canonical weakly interacting massive particles. In this work we search for such oscillation effects in the spectra of supernova remnants caused by the photon-ALP conversion, using the Fermi Large Area Telescope data. Three bright supernova remnants, IC443, W44, and W51C, are analyzed. The inclusion of photon-ALP oscillations yields an improved fit to the $γ$-ray spectrum of IC443, which gives a statistical significance of $4.2σ$ in favor of …
The observation of the $\barν_e$ energy spectrum from a supernova burst can provide constraints on neutrino oscillations. We derive formulas for adiabatic oscillations of supernova antineutrinos for a variety of 3- and 4-neutrino mixing schemes and mass hierarchies which are consistent with the LSND evidence for $\barν_μ\to \barν_e$ oscillations. Finally, we explore the constraints on these models and LSND given by the supernova SN1987A $\barν_e$'s observed by the Kamiokande-2 and IMB-3 detectors.
Mounting evidence indicates that neutrinos likely undergo fast flavor conversion (FFC) in at least some core-collapse supernovae. Outcomes of FFC, however, remain highly uncertain. Here we study the cascade of flavor-field power from large angular scales in momentum space down to small ones, showing that FFC enhances this process and thereby hastens relaxation. Cascade also poses a computational challenge, which is present even if the flavor field is stable: When power reaches the smallest angular scale of the calculation, error from truncating the angular-moment expansion propagates back to l…
By using Laplace transformation we developed an approximate solution to describe neutrino oscillation probabilities in arbitrary density matter. We show that this approximation solution is valid when matter potential V satisfy $V< Δm^2/2E$ and $\int VL<1$, where $L$ is the length of the neutrino oscillation . Thus, the formula is useful for propagation of the solar or supernova neutrinos with terrestrial matter effect.
We discuss some possible influence of neutrino oscillations on physics of supernova mainly focusing on the observations of $\barν_e$, and present some analysis of SN1987A data in the light of three neutrino mixing scheme.
The conversion between photons and axionlike particles (ALPs) in the Milky Way magnetic field could result in the detectable oscillation phenomena in $γ$-ray spectra of Galactic sources. In this work, the GeV (Fermi-LAT) and TeV (MAGIC/VERITAS/H.E.S.S.) data of three bright supernova remnants (SNRs, ie. IC443, W51C and W49B) have been adopted together to search such the oscillation effect. Different from our previous analysis of the sole Fermi-LAT data of IC443, we do not find any reliable signal for the photon-ALP oscillation in the joint broadband spectrum of each SNR. The reason for the inc…
Observing a high-statistics neutrino signal from a galactic supernova (SN) would allow one to test the standard delayed explosion scenario and may allow one to distinguish between the normal and inverted neutrino mass ordering due to the effects of flavor oscillations in the SN envelope. One may even observe a signature of SN shock-wave propagation in the detailed time-evolution of the neutrino spectra. A clear identification of flavor oscillation effects in a water Cherenkov detector probably requires a megatonne-class experiment.
We summarize our current understanding of the neutrino flavor conversions inside a core collapse supernova, clarifying the important role played by the "collective effects" in determining flavor conversion probabilities. The potentially observable $ν_e$ and $\barν_e$ spectra may help us identify the neutrino mixing scenario, distinguish between primary flux models, and learn more about the supernova explosion.
The level-crossing probability, local and global adiabaticity conditions are discussed for 2-flavour neutrino oscillations in matter with arbitrary mixing angle $θ$. Different approximations for the survival probability of supernova neutrinos are compared. Results of a combined likelihood analysis of the observed SN1987A neutrino signal and of the latest solar neutrino data including the recent SNO CC measurement are presented.
We extend the multi-angle computational framework and investigate the time evolution of the neutrino halo on collective neutrino oscillation in the core collapse of an iron core progenitor. We find that in the case of the $9.6\, \rm M_\odot$ progenitor adopted in this work, there are windows of time when the effects of neutrino halo and collective neutrino oscillation are not simultaneously large. Inside the shock, the impact of the inward-scattered halo neutrino cannot in general be neglected compared to the outward-propagating neutrino flux. However, during early epochs, collective neutrino …
In order to investigate the impact of collective neutrino oscillations (CNO) on the neutrino signal from a nearby supernova, we perform 3-flavor neutrino oscillation simulations employing the multiangle effect. The background hydrodynamic model is based on the neutrino hydrodynamic simulation of a 8.8 \Msun progenitor star. We find that CNO commences after some 100 ms post bounce. Before this, CNO is suppressed by matter-induced decoherence. In the inverted mass hierarchy, the spectrum of $\barν_e$ becomes softer after the onset of CNO. To evaluate the detectability of this modification, we de…
A liquid Argon TPC (ICARUS-like) has the ability to detect clean neutrino bursts from type-II supernova collapses. In this paper, we consider for the first time the four possible detectable channels, namely, the elastic scattering on electrons from all neutrino species, $ν_e$ charged current absorption on $Ar$ with production of excited $K$, $\barν_e$ charged current absorption on $Ar$ with production of excited $Cl$ and neutral current interactions on $Ar$ from all neutrino flavors. We compute the total rates and energy spectra of supernova neutrino events including the effects of the three--…
Rapid progress has been made during recent years in the understanding of the flavour oscillations that occur as neutrinos traverse through supernova. The previous paradigm has given way and it is now clear that the neutrino signals we shall receive from future Galactic supernovae will allow us both to peer inside these extraordinary cosmic events and to probe some of the fundamental properties of these elusive particles. In this review we aim to distill the progress that has been made focusing upon the effects of the dynamic density profile and the emergence of collective flavour oscillations …
A dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial) spherical symmetry about the center of the supernova and the (directional) axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this paper we analyze the neutrino…
We study the effects of neutrino oscillation on supernova neutrino in the case of the inverted mass hierarchy ($m_{3} \ll m_{1} < m_{2}$) as well as the normal mass hierarchy ($m_{1} < m_{2} \ll m_{3}$). Numerical analysis using a realistic supernova and presupernova model allows us to discuss quantitatively a possibility to probe neutrino oscillation parameters. We show that information about the mass hierarchy can be obtained if $θ_{13}$ is rather large ($\sin^{2}{2 θ_{13}} > 10^{-3}$) and that $θ_{13}$ can be well probed by SuperKamiokande if the neutrino mass hierarchy is the inverted case…
In this paper we construct the interaction potential between the dense supernova core and neutrinos due to the exchange of light radions in the Randall-Sundrum scenario. We then show that the radion exchange potential affects the neutrino oscillation phenomenology inside the supernova significantly if the radion mass is less than around 1 GeV. In order that the Bethe-Wilson mechanism for heating the envelope and r-process neucleosynthesis be operative, the radion mass must be greater than 1 GeV. Bounds on the radion mass of the same order of magnitude can also be derived from TASSO and CLEO da…
We investigate collective flavor oscillations of supernova neutrinos at late stages of the explosion. We first show that the frequently used single-angle (averaged coupling) approximation predicts oscillations close to, or perhaps even inside, the neutrinosphere, potentially invalidating the basic neutrino transport paradigm. Fortunately, we also find that the single-angle approximation breaks down in this regime; in the full multiangle calculation, the oscillations start safely outside the transport region. The new suppression effect is traced to the interplay between the dispersion in the ne…
We study two-flavor collective neutrino oscillations in the dense-neutrino region above the neutrino sphere in a supernova (SN). The angular dependence of the neutrino-neutrino interaction potential causes "multi-angle" effects that can lead either to complete kinematical decoherence in flavor space or only to small differences between different trajectories. This nonlinear system switches abruptly between "self-maintained coherence" and "self-induced decoherence" among the angular modes, depending on the strength of the deleptonization flux. For a realistic SN the quasi single-angle behavior …
Recently, Csaki, Kaloper and Terning (CKT) suggested that axion-photon oscillation in the intergalactic medium can explain the observed dimming of distant type Ia supernovae. This mechanism works only if the initial axion flux is much smaller than the initial photon flux. We study several mechanisms for such initial axion production. The direct axion production in the supernovae, the photon-axion oscillation in the magnetic field of supernovae and in the magnetic field of their host galaxies are addressed. We find it likely that the initial axion flux is very small and therefore does not pose …
We revisit our previous results on the matter suppression of self-induced neutrino flavor conversions during a supernova (SN) accretion phase, performing a linearized stability analysis of the neutrino equations of motion, in the presence of realistic SN density profiles. In our previous numerical study, we used a simplified model based on an isotropic neutrino emission with a single typical energy. Here, we take into account realistic neutrino energy and angle distributions. We find that multi-energy effects have a sub-leading impact in the flavor stability of the SN neutrino fluxes with resp…
We investigate effects of non-zero Dirac and Majorana CP violating phases on neutrino-antineutrino oscillations in a magnetic field of astrophysical environments. It is shown that in the presence of strong magnetic fields and dense matter, non-zero CP phases can induce new resonances in the oscillations channels $ν_e \leftrightarrow \barν_e$, $ν_e \leftrightarrow \barν_μ$ and $ν_e \leftrightarrow \barν_τ$. We also consider all other possible oscillation channels with $ν_μ$ and $ν_τ$ in the initial state. The resonances can potentially lead to significant phenomena in neutrino oscillations acce…
The effects of three-flavor neutrino oscillation on the supernova neutrino spectrum are studied. We calculate the expected event rate and energy spectra, and their time evolution at the Superkamiokande (SK) and the Sudbury Neutrino Observatory (SNO), by using a realistic neutrino burst model based on numerical simulations of supernova explosions. We also employ a realistic density profile based on a presupernova model for the calculation of neutrino conversion probability in supernova envelopes. These realistic models and numerical calculations allow us to quantitatively estimate the effects o…
If the lepton numbers are associated with global symmetries spontaneously broken at a scale below 1 TeV, neutrino oscillations in supernovae produce classic Majoron fields that perturb the neutrino propagation itself and may change the oscillation patterns in the periods of largest $ν$ fluxes. The impact of the Majoron fields on the same transitions as $ν_{e}\to ν_{X}$ that presumably occur in the Sun is studied in the case of the non-adiabatic MSW solution. It is shown how the back reaction of the Majoron fields may improve the adiabaticity of these oscillations in a supernova environment whi…
Neutrinos and antineutrinos of all three flavours are emitted during the post bounce phase of a core collapse supernova with $\numu/\nutau (\anumu/\anutau)$ having average energies more than that of $\nue(\anue)$. They can be detected by the new earth bound detector like SNO and Super-Kamiokande which are sensitive to neutrinos of all three flavours. In this letter we consider the effect of flavour oscillations on the neutrino flux and their expected number of events at the detector. We do a three-generation analysis and for the mass and mixing schemes we first consider the threefold maximal m…
Several extensions of the standard electroweak model allow new four-fermion interactions (nu_a nu_b * ff) with strength eps_ab*G_F, where (a,b) are flavor indices. We revisit their effects on flavor oscillations of massive (anti)neutrinos in supernovae, in order to achieve, in the region above the protoneutron star, an analytical treatment valid for generic values of the neutrino mixing angles (omega,phi,psi)=(theta_12,theta_13,theta_23). Assuming that eps_ab<<1, we find that the leading effects on the flavor transitions occurring at high (H) and low (L) density along the supernova matter prof…
In this review, the effect of flavor oscillations on the neutrinos released during supernova explosion after core collapse is described. In some scenarios there are large enhancement of the number of events compared to the no oscillation case. Various other features associated with supernova neutrinos are also discussed.
We study electron-neutrino and electron-antineutrino signals from a supernova with strong magnetic field detected by a 100 kton liquid Ar detector. The change of neutrino flavors by resonant spin-flavor conversions, matter effects, and neutrino self-interactions are taken into account. Different neutrino signals, characterized by neutronization burst event and the total event numbers of electron-neutrinos and electron-antineutrinos, are expected with different neutrino oscillation parameters and neutrino magnetic moment. Observations of supernova neutrino signals by a 100 kton liquid Ar detect…
Supernova neutrinos have several exceptional features which can lead to interesting physical consequences. At the production point their wave packets have an extremely small size $σ_x \sim 10^{-11}$ cm; hence the energy uncertainty can be as large as the energy itself, $σ_E \sim E$, and the coherence length is short. On the way to the Earth the wave packets of mass eigenstates spread to macroscopic sizes and separate. Inside the Earth the mass eigenstates split into eigenstates in matter and oscillate again. The coherence length in the Earth is comparable with the radius of the Earth. We explo…
In a 1996 JRO Fellowship Research Proposal (Los Alamos), the author suggested that neutrino oscillations may provide a powerful indirect energy transport mechanism to supernovae explosions. The principal aim of this addendum is to present the relevant unedited text of Section 1 of that proposal. We then briefly remind, (a) of an early suggestion of Mazurek on vacuum neutrino oscillations and their relevance to supernovae explosion, and (b) Wolfenstein's result on suppression of the effect by matter effects. We conclude that whether or not neutrino oscillations play a significant role in supern…
We demonstrate the non-negligible effect of transition magnetic moments on three-flavor collective oscillations of Majorana neutrinos in the core of type-II supernovae, within the single-angle approximation. We argue that data from a galactic supernova in conjunction with terrestrial experiments can potentially give us clues about the non-zero nature of neutrino transition magnetic moments if these are Majorana fermions, even if their values are as small as those predicted by the Standard Model augmented by nonzero neutrino Majorana masses.
Neutral currents induced matter oscillations of electroweak-active (anti-)neutrinos to sterile neutrinos can explain the observed motion of pulsars. In contrast to a recently proposed explanation of the pulsar birth velocities based on the electron to tau (muon) neutrino oscillations [hep-ph/9606428], the heaviest neutrino (either active or sterile) would have to have mass of order several keV.
Core collapse supernovae are a huge source of all flavor neutrinos. The flavor composition, energy spectrum and time structure of the neutrino burst from a galactic supernova can provide information about the explosion mechanism and the mechanisms of proto neutron star cooling. Such data can also give information about the intrinsic properties of the neutrino such as flavor oscillations. One important question is to understand to which extend can the supernova and the neutrino physics be decoupled in the observation of a single supernova. In this paper we discuss the possibility to probe the n…
Neutrinos emitted during stellar core collapse leading to a supernova are primarily of the electron neutrino type at source which may undergo oscillation between flavor eigenstates during propagation to an earth-bound detector. Although the number of neutrinos emitted during the pre-bounce collapse phase is much smaller than that emitted in the post-bounce phase (in which all flavors of neutrinos are emitted), a nearby supernova event may nevertheless register a substantial number of detections from the pre-bounce phase at SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). The ca…
Light element synthesis in supernovae through neutrino-nucleus interactions, i.e., the nu-process, is affected by neutrino oscillations in the supernova environment. There is a resonance of 13-mixing in the O/C layer, which increases the rates of charged-current nu-process reactions in the outer He-rich layer. The yields of 7Li and 11B increase by about a factor of 1.9 and 1.3, respectively, for a normal mass hierarchy and an adiabatic 13-mixing resonance, compared to those without neutrino oscillations. In the case of an inverted mass hierarchy and a non-adiabatic 13-mixing resonance, the inc…
Supernova neutrinos, which arrive at Earth earlier than light, allow for the earliest determination of the direction of the supernova. The topic of this paper is to study how accurately we can determine the supernova direction. We simulate supernova neutrino events at the SuperKamiokande detector, using a realistic supernova model and several realistic neutrino oscillation models. With the results of our simulation, we can restrict the supernova direction to be within a circle of radius $9^\circ$. In several neutrino oscillation models, this accuracy is increased to $8^\circ$. We also discuss …
We point out that solar neutrino oscillations with large mixing angle as evidenced in current solar neutrino data have a strong impact on strategies for diagnosing collapse-driven supernova (SN) through neutrino observations. Such oscillations induce a significant deformation of the energy spectra of neutrinos, thereby allowing us to obtain otherwise inaccessible features of SN neutrino spectra. We demonstrate that one can determine temperatures and luminosities of non-electron flavor neutrinos by observing bar{nu}_{e} from galactic SN in massive water Cherenkov detectors by the charged curren…
I shall review some of the recent results concerning the astrophysics of a core collapse supernova (SN) and neutrino oscillations. Neutrinos play an important role in the SN explosion, and they also carry most of the energy of the collapse. The energy spectra of neutrinos and antineutrinos arriving at the Earth incorporate information on the primary neutrino fluxes as well as the neutrino mixing scenario. The analysis of neutrino propagation through the matter of the supernova and the Earth, combined with the observation of a neutrino burst from a galactic SN, enables us to put limits on the m…
Fast-pairwise collective neutrino oscillation represents a key uncertainty in the theory of core-collapse supernova (CCSN). Despite the potentially significant impact on CCSN dynamics, it is usually neglected in numerical models of CCSN because of the formidable technical difficulties of self-consistently incorporating this physics. In this paper, we investigate the prospects for the occurrence of fast flavor conversion by diagnosing electron neutrino lepton number (ELN) crossing in more than a dozen state-of-the-art three-dimensional CCSN models. ELN crossings is a necessary condition for tri…
We review the rich phenomena associated with neutrino flavor transformation in the presence of neutrino self-coupling. Our exposition centers on three collective neutrino oscillation scenarios: a simple bipolar neutrino system that initially consists of mono-energetic electron neutrinos and antineutrinos; a homogeneous and isotropic neutrino gas with multiple neutrino/antineutrino species and continuous energy spectra; and a generic neutrino gas in an anisotropic environment. We use each of these scenarios to illustrate key facets of collective neutrino oscillations. We discuss the implication…
We investigate the initial progenitor mass dependence of the early-phase neutrino signal from supernovae taking neutrino oscillations into account. The early-phase analysis has advantages in that it is not affected by the time evolution of the density structure of the star due to shock propagation or whether the remnant is a neutron star or a black hole. The initial mass affects the evolution of the massive star and its presupernova structure, which is important for two reasons when considering the neutrino signal. First, the density profile of the mantle affects the dynamics of neutrino oscil…
Leptonic CP violation is one of the most important topics in neutrino physics. CP violation in the neutrino sector is strongly related to the nature of neutrinos: whether they are Dirac or Majorana particles. In \cite{Popov:2021icg} we have shown that for Majorana neutrinos arance of nonzero Majorana CP-violating phases combined with strong magnetic field during supernova core-collaple can induce new resonances in neutrino oscillations, for example in $ν_e \to \barν_τ$ channel. In this contribution we further study new resonances in Majorana neutrino oscillations, in particular energy dependen…
Core collapse supernovae are unique laboratories to study many aspects of neutrino physics. The vicinity of the proto-neutron star in a core-collapse supernova is characterized by large matter and neutrino densities. A salient feature of this region is the impact of neutrino-neutrino interactions. Properties of the ensuing non-linear many-neutrino system are examined with a particular emphasis on its collective behavior and its symmetries. The impact of neutrino properties and interactions on the r-process nucleosynthesis that may take place in the supernova environment is discussed.
In supernovae neutrinos are emitted from a region with a width $r_{\rm eff}$ of a few kilometers (rather than from a surface of infinitesimal width). We study the effect of integration (averaging) over such an extended emission region on collective oscillations. The averaging leads to additional suppression of the correlation (off-diagonal element of the density matrix) by a factor $ \sim 1/r_{\rm eff} V_e \sim 10^{-10}$, where $V_e$ is the matter potential. This factor enters the initial condition for further collective oscillations and, consequently, leads to a delay of the strong flavour tr…
We show that the bump in the electron number density profile at the base of the hydrogen envelope in O-Ne-Mg core-collapse supernovae causes an interesting interplay between neutrino-electron and neutrino-neutrino forward scattering effects in the flavor evolution of low-energy nu_e in the neutronization burst. The bump allows a significant fraction of the low-energy nu_e to survive by rendering their flavor evolution nonadiabatic. Increasing the luminosity of the neutronization burst shifts the bump-affected nu_e to lower energy with reduced survival probability. Similarly, lowering the lumin…
Analyses of observable supernova neutrino oscillation effects require the calculation of the electron (anti)neutrino survival probability P_ee along a given supernova matter density profile. We propose a simple analytical prescription for P_ee, based on a double-exponential form for the crossing probability and on the concept of maximum violation of adiabaticity. In the case of two-flavor transitions, the prescription is shown to reproduce accurately, in the whole neutrino oscillation parameter space, the results of exact numerical calculations for generic (realistic or power-law) profiles. Th…
We study the neutrino spin oscillations, i.e., neutrino spin precession caused by the neutrino interaction with matter polarized by external magnetic field (or, equivalently, by the interaction of the induced magnetic moment (IMM) of a neutrino with the magnetic field). In the analysis, we consider realistic conditions inside supernovae and discuss both the Dirac and Majorana cases. We show that due to the interaction with the polarized matter a neutrino flux from a supernova suffers additional attenuation at low neutrino energies. Another possible effect is that when taken together the effect…
Core-collapse supernovae are among Nature's grandest explosions. They are powered by the energy released in gravitational collapse and include a rich set of physical phenomena involving all fundamental forces and many branches of physics and astrophysics. We summarize the current state of core-collapse supernova theory and discuss the current set of candidate explosion mechanisms under scrutiny as core-collapse supernova modeling is moving towards self-consistent three-dimensional simulations. Recent work in nuclear theory and neutron star mass and radius measurements are providing new constra…
The neutrino flux close to a supernova core contributes substantially to neutrino refraction so that flavor oscillations become a nonlinear phenomenon. One unexpected consequence is efficient flavor transformation for anti-neutrinos in a region where only neutrinos encounter an MSW resonance or vice versa. Contrary to previous studies we find that in the neutrino-driven wind the electron fraction Y_e always stays below 0.5, corresponding to a neutron-rich environment as required by r-process nucleosynthesis. The relevant range of masses and mixing angles includes the region indicated by LSND, …
By performing a series of one- and two-dimensional (1-, 2D) hydrodynamic simulations with spectral neutrino transport, we study possible impacts of collective neutrino oscillations on the dynamics of core-collapse supernovae. To model the spectral swapping which is one of the possible outcome of the collective neutrino oscillations, we parametrize the onset time when the spectral swap begins, the radius where the spectral swap occurs, and the threshold energy above which the spectral interchange between heavy-lepton neutrinos and electron/anti-electron neutrinos takes place, respectively. By d…
