Neutrino Heating Research Articles

Report on the progress of supernova research by the Livermore group

We report on the current state of our research in the understanding of the evolution of core collapse supernovae. Convection in the post collapse stellar core (proto neutron star) is an important ingredient to the success of the neutrino heating mechanism; we discuss our model and indicate the sensitivity of our calculations to the inclusion of this convective model.

Postcollapse hydrodynamics of SN 1987A - Two-dimensional simulations of the early evolution

The first few seconds of the explosion of SN 1987A are modeled here using a 2D cylindrical geometry smooth particle hydrodynamics code. The success of the explosion is determined to be sensitive to the duration of the infall, the timing of the bounce, and the subsequent neutrino heating. A semianalytical model for the initial structure of the collapsed object is used to present two simulations that differ by the mass that has been allowed to collapse into a neutron star prior to the bounce. In the case of a short initial infall, the explosion fails due to excessive cooling. For a longer initial infall, the cooling is less and the explosion is successful although relatively weak. It is shown that in this case, a successful explosion is brought about by the presence of an entropy gradient which, combined with the gravitational pull of the neutron star, leads to extremely strong instabilities. The critical importance of the global circulation for the success of the explosion is demonstrated.

Can a closure mass neutrino help solve the supernova shock reheating problem?

view Abstract Citations (104) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Can a Closure Mass Neutrino Help Solve the Supernova Shock Reheating Problem? Fuller, George M. ; Mayle, R. ; Meyer, Bradley S. ; Wilson, James R. Abstract It is pointed out that a nu(mu) or nu(tau) neutrino with a cosmologically significant mass (10-100 eV) are a small mixing with a light nu(e) would result in a matter-enhanced Mikheyev-Smirnov-Wolfenstien resonant transformation between these species in a region above the neutrino sphere but below the stalled shock during the reheating phase of a Type II supernova. The neutrino heating behind the shock is due to charged-current nu(e) and average nu(e) captures. Since the nu(mu) and nu(tau) have considerably higher average energies than do the nu(e), neutrino flavor mixing would result in higher effective nu(e) energies behind the shock and a concomitant increase in the heating rate. Numerical calculations suggest that this effect results in a 60 percent increase in the supernova explosion energy, possibly to solve the energy problem of delayed-mechanism supernova models. Publication: The Astrophysical Journal Pub Date: April 1992 DOI: 10.1086/171228 Bibcode: 1992ApJ...389..517F Keywords: Neutrinos; Particle Mass; Shock Heating; Supernovae; Astronomical Models; Background Radiation; Hubble Constant; Astrophysics; ELEMENTARY PARTICLES; SHOCK WAVES; STARS: SUPERNOVAE: GENERAL full text sources ADS | data products SIMBAD (1)

Effect of neutrino heating in the early Universe on neutrino decoupling temperatures and nucleosynthesis.

The neutrino energy-loss rates during pair annihilation in the early Universe are calculated using the formulation of Herrera and Hacyan and assuming neutrinos to be massless. The work is extended to include the neutrinos of the muon and tauon families, and a method to calculate the evolution of neutrino temperatures is suggested. It is found that neutrinos of the electron family decouple at 1.5\ifmmode\times\else\texttimes\fi{}${10}^{10}$ K, and those of the other families at 2.5\ifmmode\times\else\texttimes\fi{}${10}^{10}$ K. The former component is heated by about 0.36%, resulting in a reduction of the primordial abundance by a mass fraction of helium (${Y}_{p}$) in the standard hot big-bang model by about 0.003.

Neutron star thermal evolution

view Abstract Citations (117) References (51) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Neutron Star Thermal Evolution van Riper, Kenneth A. Abstract A model is presented for calculating the evolution of neutron stars in the thermal evolution approximation, which follows the detailed temperature dependence in the interior of the star assuming a fixed density structure. A new numerical algorithm for solving the thermal evolution equations is presented and comparisons are made with other algorithms. The neutrino emissivities, heat capacities, thermal conductivities, and superfluid treatment used in the models are described. Results of the thermal evolution model are presented for representative neutron star models of a gravitational mass M = 1.4 solar mass with and without strong surface magnetic fields, and also for stars with a central accelerated cooling mechanism. Isothermal cooling models are examined to determine the ages beyond which the cooling model applies. Publication: The Astrophysical Journal Supplement Series Pub Date: February 1991 DOI: 10.1086/191538 Bibcode: 1991ApJS...75..449V Keywords: Neutron Stars; Stellar Evolution; Stellar Interiors; Stellar Temperature; X Ray Stars; Computational Astrophysics; Stellar Mass; Stellar Models; Astrophysics; DENSE MATTER; STARS: EVOLUTION; STARS: INTERIORS; STARS: NEUTRON; STARS: X-RAYS full text sources ADS |

Convection in core collapse supernovae

The final explosion energy of supernovae produced by the late time neutrino heating mechanism in sensitive to the magnitude of the total neutrino luminosity streaming from the proto-neutron star remnant. In this paper we show that convection can occur on timescales important to the late time mechanism. The neutrino luminosity is thus enhanced, with a corresponding increase in the explosive energy, more than double the value obtained from numerical models of supernovae without convection.

Neutrino heating in supernovae.

I argue that standard descriptions of stellar collapse omit the primary mechanism for dissipative neutrino reactions in nuclear matter, nuclear excitation by neutral-current scattering. The nuclear heating rate, due to primarily to muon- and tauon-neutrino excitation of giant resonance states, is on the order of 90 MeV/nucleon sec at a radius of 100 km. I discuss possible effects of both neutral- and charged-current neutrino heating in models of stellar collapse.

The neutrino radiation of collapsing stellar cores and the neutrino burst detected from SN 1987 A

The properties of the neutrino burst generated by massive 1.5–2M⊙ collapsing stellar iron-oxygen cores are discussed. Special attention is given to the neutrino heat conductivity theory which allows us to calculate the transport of neutrinos through the collapsing stellar core up to the formation and during the first seconds of cooling of a hot hydrostatic neutron star. The theoretical predictions seem to be in good agreement with both the KAMIOKANDE II and IMB data on the neutrino burst detected from SN 1987A. The most reliable constraint on the neutrino rest mass is shown to bemv<20–30eV, while the safest upper limit on the neutrino magnetic moment, µv < 10−11 Bohr magnetons, results rather from the cooling of white dwarfs than from the SN 1987A neutrino data.

Convection in supernova theory

view Abstract Citations (25) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Convection in Supernova Theory Bethe, H. A. ; Brown, G. E. ; Cooperstein, J. Abstract Convection takes place behind the shock front if and when the strength of the shock declines. However, the convection does not strengthen the shock but weakens it. It is therefore useless for promoting an early explosion (at times of order 10 ms). At late times (several tenths of a second), convection may take place behind the neutrino sphere and may increase the strength of the late shock caused by neutrino heating. Publication: The Astrophysical Journal Pub Date: November 1987 DOI: 10.1086/165715 Bibcode: 1987ApJ...322..201B Keywords: Convection; Shock Wave Interaction; Stellar Models; Supernovae; Energy Distribution; Neutrinos; Plasma Heating; Shock Fronts; Astrophysics; CONVECTION; NEUTRINOS; SHOCK WAVES; STARS: SUPERNOVAE full text sources ADS |

Late-time neutrino heating and energetics of stalled shocks in Type II supernovae

view Abstract Citations (4) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Late-Time Neutrino Heating and Energetics of Stalled Shocks in Type II Supernovae Ray, A. ; Kar, K. Abstract The hydrodynamic shock formed outside the homologously collapsing core of a Type II supernova progenitor seems to stall for certain mass ranges in many numerical calculations. A way to revive the stalled shock through late-time neutrino heating was proposed by Bethe and Wilson (1985). Here semianalytic models are used to calculate the extent of neutrino heating self-consistently with the changes in nuclear equilibrium behind the shockfront. Heating rate seems to be extremely rapid during a particular short phase of shock recession and whether the shock is revived sufficiently or not depends critically on the total neutrino luminosity and to a lesser extent on the neutrino-sphere radius. Publication: The Astrophysical Journal Pub Date: August 1987 DOI: 10.1086/165440 Bibcode: 1987ApJ...319..143R Keywords: Gravitational Collapse; Neutrinos; Plasma Heating; Shock Waves; Supernovae; Stellar Cores; Time Dependence; Astrophysics; NEUTRINOS; SHOCK WAVES; STARS: COLLAPSED; STARS: SUPERNOVAE full text sources ADS |

Effects of high-energy neutrino production and interactions on stars in close X-ray binaries

Limits are discussed that may be placed on binary systems in which a compact partner is a strong source of high-energy particles that produce photons, neutrinos, and other secondary particles in the companion star. The highest energy neutrinos are absorbed deep in the companion and the associated energy deposition may be large enough to affect its structure or lead to its ultimate disruption. This neutrino heating is evaluated, starting with a detailed numerical calculation of the hadronic cascade induced in the atmosphere of the companion star. For some theoretical models, the resulting energy deposition from neutrino absorption may be so great as to disrupt the companion star over a time scale of 10,000-100,000 yr. Even if the energy deposition is smaller, it may still be high enough to alter the system substantially.

Type II supernova models. Nucleosynthesis and isotopic anomalies

Core-collapse models of type II supernovae are discussed. The conditions for prompt explosions caused by a hydrodynamic shock wave as well as the prospects of delayed explosions triggered by neutrino heating are investigated. Predictions of nucleosynthetic yields from various models are presented and are compared with observations. It will be shown that massive stars. M ⋍ (25±5) M⊚ will eject most of the elements from oxygen to the iron group in roughly solar relative abundances. If they indeed do explode, but that the site of formation of neutron-rich isotopes of the elements beyond iron is still not known. Finally, it will be discussed whether type II supernovae can serve as an explanation of isotopic anomalies found in certain meteoritic inclusions.

Revival of a stalled supernova shock by neutrino heating

view Abstract Citations (802) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Revival of a stalled supernova shock by neutrino heating Bethe, H. A. ; Wilson, J. R. Abstract The mechanism for revival of a stalled supernova shock found by Wilson (1982) in a computation is analyzed. Neutrinos from the hot, inner core of the supernova are absorbed in the outer layers, and although only about 0.1 percent of their energy is so absorbed, this is enough to eject the outer part of the star and leave only enough mass to form a neutron star. The neutrino absorption is independent of the density of material. After the shock recedes to some extent, neutrino heating establishes a sufficient pressure gradient to push the material beyond about 150 km outward, while the material further in falls rapidly toward the core. This makes the density near 150 km decrease spectacularly, creating a quasi-vacuum in which the pressure is mainly carried by radiation. This is a perfect condition to make the internal energy of the matter sufficient to escape from the gravitational attraction of the star. The net energy of the outgoing shock is about 4 x 10 to the 50th ergs. Publication: The Astrophysical Journal Pub Date: August 1985 DOI: 10.1086/163343 Bibcode: 1985ApJ...295...14B Keywords: Heating; Neutrinos; Shock Waves; Supernovae; Thermalization (Energy Absorption); Computational Astrophysics; Explosions; Neutron Stars; Particle Collisions; Astrophysics full text sources ADS |

Neutrino chemical potential and neutrino heat conductivity with allowance for neutrino scattering

The equations of neutrino hydrodynamics are derived in two different approximations taking into consideration the neutrino scattering from stellar material. In a thermal-conductivity approximation which holds good when neutrino optical depth with respect to absorption exceeds 1, the neutrino scattering is taken into account, analogously with photon radiative conductivity, by introducing the transport cross-section in the neutrino mean free path. In a practically important case when the neutrino optical thickness with respect to scattering is high enough, whereas that concerning absorption is sufficiently low, another approximation of ‘Comptonized’ neutrinos is valid. In this case, the neutrino and antineutrino chemical potentials are independent of each other. They have to be calculated from equations of continuity established for neutrino and antineutrino alongside with the diffusion equation expressing the law of lepton-charge conservation. The equations of neutrino hydrodynamics are written out both with and without inclusion of muon neutrinos and antineutrinos.

The neutrino radiation for a hot neutron star formation and the envelope outburst problem

With the equations of neutrino heat conductivity being used, the neutrino light curve is calculated for the spherically symmetrical collapse of an iron-oxygen 2M ⊙ star (Figure 1) up to the formation of a hot hydrostatically equilibrium neutron star. The total energy, radiated in the form of muon and electron neutrinos, is 5.8×1053 erg (0.16Mc 2). The mean neutrino particle energy is ∼12 MeV for all the time the collapse proceeds. The maximum neutrino luminosity value is equal to 3×1053 erg s−1. For a 10M ⊙ star collapse, the luminosity maximum 3×1054 erg s−1 takes place just at the moment of the formation of a black hole inside the collapsing star. The total radiated energy in this case is about 0.08Mc 2. The set of calculations, allowing for the deposition of momentum by means of neutrino-nuclear coherent scattering, brings us to a conclusion that the envelope outburst is only possible if the scattering cross-section is 50 times larger than the value experimentally accepted (inequality 20)).

Ignition of thermonuclear reactions by the neutrino radiation and supernova explosions

It is pointed out that in collapsing carbon-oxygen stars ( M ⩽ 2 M ⊙) the neutrino heating initiates carbon and oxygen explosion in the stellar mantle leading to its ejection, i.e., to Supernova explosion. The main heating mechanism is the neutrino-electron scattering.