The role of neutrinos in collapse-driven supernovae (original) (raw)
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Core-Collapse Supernovae Induced by Anisotropic Neutrino Radiation
EAS Publications Series, 2004
We demonstrate the important role of anisotropic neutrino radiation on the mechanism of core-collapse supernova explosions. Through a new parameter study with a fixed radiation field of neutrinos, we show that prolate explosions caused by globally anisotropic neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given. This is suggestive of the fact that the expanding materials of SN 1987A has a prolate geometry.
Hamburg Neutrinos From Supernova Explosions, 2011
We review the current status of the core-collapse supernova (CCSN) mechanism, beginning with a very brief account of CCSN types, and of the growing number of observations of their corresponding progenitors. This is followed by a brief account of current developments in the modeling of CCSNe progenitors, and of the four main supernova mechanisms under current study. We then focus on the current status of the neutrino mechanism, describing its essential features, as this mechanism seems the most promising at this time. We follow with a brief description of current efforts at the very computationally demanding challenge of modeling the neutrino mechanism, ending with a brief description of our CHIMERA code and some recent results obtained with this code.
We demonstrate the importance of anisotropic neutrino radiation in the mechanism of core-collapse supernova explosions. Through a new parameter study with a fixed radiation field of neutrinos, we show that global anisotropy of the neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given. We discuss the reason why, and demonstrate how sensitively the success of a supernova explosion depends on the neutrino luminosity.
Effect of Anisotropic Neutrino Radiation on Supernova Explosion Energy
The Astrophysical Journal, 2001
Since SN 1987A, many observations have indicated that supernova explosions are not spherical. The cause of the asymmetric explosion is still controversial (e.g., asymmetry in the envelope, the convective engine in the central core or in the protoÈneutron star). In our previous study, anisotropic neutrino radiation has been proposed as an explanation for this asymmetry. In this paper we carried out a series of systematic multidimensional numerical simulations in order to investigate the e †ect of anisotropic neutrino radiation itself on the supernova explosion energy. The neutrino luminosity and the degree of anisotropy in neutrino radiation were assumed as input parameters, and the numerical results for various parameters were compared with each other. It was found that only a few percent of anisotropy in the neutrino emission distribution is sufficient to increase the explosion energy by a large factor. The explosion energy calculated so far in many supernova models has tended to be too short to explain the observation. Anisotropy of 10% in neutrino radiation roughly corresponds to an enhancement of 4% in total neutrino luminosity as far as the explosion energy is concerned. The increase in the explosion energy due to anisotropic neutrino radiation can be explained as follows. Anisotropically emitted neutrinos locally heat the supernova matter and revive a stalled shock wave in the direction of enhanced radiation. The expansion of the gas by the shock propagation results in a decrease in the neutrino cooling (emission) rate that rapidly decreases with the matter temperature. It is this suppression of energy loss that contributes largely to the increase in explosion energy. The efficiency of neutrino heating (absorption) itself is almost unchanged between anisotropic and spherical models with available energy Ðxed for neutrinos. In order for a stalled shock wave to revive, enhancement of the local intensity in the neutrino Ñux is of great importance, rather than that of the total neutrino luminosity over all the solid angle. It is Ðrst pointed out that such local neutrino heating is capable of triggering a supernova explosion. Anisotropic neutrino radiation is considered to be a plausible mechanism for a "" successful ÏÏ explosion other than the so far suggested "" convective trigger.ÏÏ Subject headings : convection È elementary particles È hydrodynamics È supernovae : general
Neutrino oscillations and supernovae
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 supernovae explosions shall depend if there are shells/regions of space in stellar collapse where matter effects play no essential role. Should such regions exist in actual astrophysical situations, the final outcome of neutrino oscillations on supernovae explosions shall depend, in part, on whether or not the LNSD signal is confirmed. Importantly, the reader is reminded that neutrino oscillations form a set of flavor-oscillation clocks and these clock suffer gravitational redshift which can be as large as 20 percent. This effect must be incorporated fully into any calculation of supernova explosion.
The essential character of the neutrino mechanism of core-collapse supernova explosions
Monthly Notices of the Royal Astronomical Society
Calibrating with detailed 2D core-collapse supernova (CCSN) simulations, we derive a simple CCSN explosion condition based solely upon the terminal density profiles of state-of-the-art stellar evolution calculations of the progenitor massive stars. This condition captures the vast majority of the behaviour of the one hundred 2D state-of-the-art models we performed to gauge its usefulness. The goal is to predict, without resort to detailed simulation, the explodability of a given massive star. We find that the simple maximum fractional ram pressure jump discriminant we define works well ∼90 per cent of the time and we speculate on the origin of the few false positives and false negatives we witness. The maximum ram pressure jump generally occurs at the time of accretion of the silicon/oxygen interface, but not always. Our results depend upon the fidelity with which the current implementation of our code F ornax adheres to Nature and issues concerning the neutrino–matter interaction, ...
Neutrinos from type Ia supernovae: the deflagration-to-detonation transition scenario
2016
It has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear - type Ia - supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption of a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characterist...
Neutrino-induced nucleosynthesis in core-collapse supernovae
Nuclear Physics A, 1991
This report was preparedas an accountof worksponsoredby an agencyof the UnitedStates _'_ f__,'_,',,7 ,_ Government, Neither the United States Governmentnor any agencythereof, nor any of their employees, makes any warranty,expressor implied,or assumesany legal liabilityor responsibility for the accuracy,completeness, or usefulnessof any information,apparatus,product, or processdisclosed,or representsthat its use wouldnot infringe privatelyowned rights. Reference herein to any specificcommercialproduct, process,or serviceby trade name, trademark, manufacturer,or otherwisedoes not necessarilyconstitute or imply its endorsement,recommendation,or favoringby the United States Governmentor any agencythereof. The views / and opinions of authors expressed herein do not n_s_iity _tatc,or reflee',those of th_ .... .I UnitedStatesGovernmentor any agencythereof. (. r,.-li stant temperature and density. This is the pre-processing phase. As the shock wave passes ,
Probing thermonuclear supernova explosions with neutrinos
Astronomy & Astrophysics, 2011
Aims. We present neutrino light curves and energy spectra for two representative type Ia supernova explosion models: a pure deflagration and a delayed detonation. Methods. We calculate the neutrino flux from β processes using nuclear statistical equilibrium abundances convoluted with approximate neutrino spectra of the individual nuclei and the thermal neutrino spectrum (pair+plasma). Results. Although the two considered thermonuclear supernova explosion scenarios are expected to produce almost identical electromagnetic output, their neutrino signatures appear vastly different, which allows an unambiguous identification of the explosion mechanism: a pure deflagration produces a single peak in the neutrino light curve, while the addition of the second maximum characterizes a delayed-detonation. We identified the following main contributors to the neutrino signal: (1) weak electron neutrino emission from electron captures (in particular on the protons 55 Co and 56 Ni) and numerous β-active nuclei produced by the thermonuclear flame and/or detonation front, (2) electron antineutrinos from positron captures on neutrons, and (3) the thermal emission from pair annihilation. We estimate that a pure deflagration supernova explosion at a distance of 1 kpc would trigger about 14 events in the future 50 kt liquid scintillator detector and some 19 events in a 0.5 Mt water Cherenkov-type detector. Conclusions. While in contrast to core-collapse supernovae neutrinos carry only a very small fraction of the energy produced in the thermonuclear supernova explosion, the SN Ia neutrino signal provides information that allows us to unambiguously distinguish between different possible explosion scenarios. These studies will become feasible with the next generation of proposed neutrino observatories.
Publications of the Astronomical Society of Japan, 2004
We have carried out 2-D simulations of core-collapse supernova explosions. The local neutrino radiation field is assumed to have its maximum value either at the symmetry (polar) axis or on the equatorial plane. These lead to the prolate and oblate explosions, respectively. We find that the gain of the explosion energy in the prolate explosion evolves more predominately than that in the oblate one when the total neutrino luminosity is given. Namely, the prolate explosion is more energetic than the oblate one.