Monte Carlo Study of Supernova Neutrino Spectra Formation

By M. T. Keil, G. Raffelt, Hans-Thomas Janka. 2002

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The neutrino flux and spectra formation in a supernova core is studied by using a Monte Carlo code. The dominant opacity contribution for νμ is elastic scattering on nucleons νμN → Nνμ, where νμ always stands for either νμ or ντ. In addition, we switch on or off a variety of processes that allow for the exchange of energy or the creation and destruction of neutrino pairs, notably nucleon bremsstrahlung NN → NNνμν̄μ, the pair annihilation processes e+e- → νμν̄μ and νeν̄e → νμν̄μ, recoil and weak magnetism in elastic nucleon scattering, elastic scattering on electrons νμe± → e±νμ, and elastic scattering on electron neutrinos and antineutrinos νμνe → νeνμ and νμν̄e → ν̄eνμ. The least important processes are neutrino-neutrino scattering and e+e- annihilation. The formation of the spectra and fluxes of νμ is dominated by the nucleonic processes, i.e., bremsstrahlung and elastic scattering with recoil, but also νeν̄e annihilation and νμe± scattering contribute significantly. When all processes are included, the spectral shape of the emitted neutrino flux is always "pinched," i.e., the width of the spectrum is smaller than that of a thermal spectrum with the same average energy. In all of our cases we find that the average ν̄μ energy exceeds the average ν̄e energy by only a small amount, 10% being a typical number. Weak-magnetism effects cause the opacity of νμ to differ slightly from that of ν̄μ, translating into differences of the luminosities and average energies of a few percent. Depending on the density, temperature, and composition profile, the flavor-dependent luminosities Lνe, Lν̄e, and Lνμ can mutually differ from each other by up to a factor of 2 in either direction.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d3e291a3360a968fc14793bc1d7d3f84c8b92be8

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Citations in the corpus

On the Normalization of the Cosmic Star Formation History (2006, result): “As found and discussed in Yüksel et al. (2005), our results favour effective temperatures at the lower end of the predicted range (Keil et al. 2003; Thompson et al. 2003; Liebendoerfer et al. 2005; Sumiyoshi et al. 2005).”
Neutrino coherent scattering rates at direct dark matter detectors (2009, background): “The neutrino spectrum of a core-collapse supernova is believed to be similar to a Fermi–Dirac spectrum, with temperatures in the range 3–8 MeV [17].”
Multidimensional supernova simulations with approximative neutrino transport. I. Neutron star kicks and the anisotropy of neutrino-driven explosions in two spatial dimensions (2006, unknown): “The values for the different neutrino types are (cf. Janka 1991b; Janka & Hillebrandt 1989; Myra & Burrows 1990; Keil et al. 2003): ηeq,νe = (µe + µp − µn)/kBT, η0,νe ≡ 3, ηeq,ν̄e = −ηeq,νe , η0,ν̄e ≡ 2, ηeq,νx = 0, η0,νx ≡ 0.”
Letter of Intent: The Precision IceCube Next Generation Upgrade (PINGU) (2014, unknown): “α [101] and using single, double and triple coincident hit modes in a χ(2) fit, 〈Eν̄e〉 and α can be extracted simultaneously.”
Symmetry energy impact in simulations of core-collapse supernovae (2013, background): “e: higher density due to dierent Q-value for charged-current reaction, =˝: highest density) resulting from weak processes that contribute to the corresponding neutrino avors (for details, see ref. [81,82,71] and references therein). The fast(slow) PNS contractions, due to the soft(sti) EOS LS220(STO”
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe (2013, background): “7: Average νe energy from fit to SNOwGLoBES-smeared, pinched-thermal spectrum as a function of time (34 kt at 10 kpc), for a flux model based on [225] and including collective oscillations, for two different MH assumptions.”
Equation-of-state dependent features in shock-oscillation modulated neutrino and gravitational-wave signals from supernovae (2008, unknown): “For both reasons the spectra of νx and ν̄e are now much more similar than in the older models (for a detailed discussion, see Raffelt 2001; Keil et al. 2003).”
Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects (2007, methodology): “According to current DSNB models [92] that are using different SN simulations [100]–[102] for the prediction of the DSNB energy spectrum and flux, the detection of ∼10 DSNB events per year is realistic for LENA.”
Current Status and Future Prospects of the SNO+ Experiment (2015, background): “τ ) energy spectra is expected to approximate a thermal spectrum [64] in the absence of neutrino flavor changing mechanisms.”
IceCube sensitivity for low-energy neutrinos from nearby supernovae (2011, background): “The analysis of the deleptonization peak that immediately follows the collapse is of considerable interest, since its magnitude and time profile are rather independent of the initial star mass and of the nuclear equation of state; the variation is estimated by (Keil et al., 2003) to be around 6 %.”
DELAYED NEUTRINO-DRIVEN SUPERNOVA EXPLOSIONS AIDED BY THE STANDING ACCRETION-SHOCK INSTABILITY (2007, background): “…of heavy-lepton neutrinos νx did not take into account the energy exchange through neutrino-nucleon scatterings and the production of νxν̄x pairs by nucleon-nucleon bremsstrahlung and by the annihilation of νeν̄e pairs (for more details, see Buras et al. 2003b, Raffelt 2001, Keil et al. 2003).”
The Status of Multi-Dimensional Core-Collapse Supernova Models (2016, background): “…(Fryer & Warren 2002; Scheck et al. 2006; Kuroda et al. 2012) cannot model neutrino heating and cooling accurately; an energy-dependent treatment is needed because of the emerging neutrino spectra are highly nonthermal with a pinched high-energy tail (Janka & Hillebrandt 1989; Keil et al. 2003).”