Recent advances in neutrino astrophysics Cristina VOLPE (AstroParticule et Cosmologie APC, Paris)
Flux (cm -2 s -1 MeV -1 ) 10 24 10 20 10 16 10 12 10 8 10 4 10 0 10-4 10-8 Neutrinos in Nature Cosmological neutrinos 330 / cm 3 Solar ν 65 milliards / cm 2 / s Supernova neutrinos Geo- neutrinos Reactor neutrinos 10 58 in 10 s Athmospheric neutrinos UHE ν 10-12 10-6 10-3 1 10 3 10 6 10 9 10 12 10 15 10 18 µev mev ev kev MeV GeV TeV PeV EeV Neutrino Energy (ev) Two diffuse neutrino backgrounds still to be observed : from the Early Universe and from supernovae
Detecting cosmological neutrinos Using radioactive nuclei? A process without threshold. Weinberg, Phys. Rev. 1962 Today at least one neutrino is non-relativistic. 100 grams of tritium gives about 10 events/year. Cocco et al., JCAP 2007 Rates (events/ev/year) Lazauskas et al., JPG2008 Electron kine.c energy (ev) PTOLEMY prototype : Princeton Tritium Observatory forlight, Early-Universe, Massive Neutrino Yield, arxiv: 1307.4738. remains a challenge!
Solar neutrinos The Sun powered from nuclear reactions that transform H into 4 He. MSW effect : resonant flavour conversion due to ν-matter interaction Wolfenstein PRD (1978) Mikheev, Smirnov(1985) mean-field ρ e ν e Survival Probability Electron neutrinos from pp chain pp 7 Be ν pep Borexino, PRL 2012 Neutrino Energy (MeV) MSW solution 8 B ν From vacuum-averaged oscillations to the MSW effect the transition might hide new physics
Solar neutrinos solar neutrino fluxes The pp-chain produces 99% of the energy. The CNO cycle, 1%, is important for advanced evolutionary stages. Flux (cm -2 s -1 ) Neutrino Energy (MeV) Current best limit on the CNO cycle from Borexino
Supernova neutrinos The gravitational collapse of massive stars (M > 8 M sun ) produces 10 57 neutrinos of about 10 MeV, all flavours, in 10 s. Suzuki, J. of Physics, Conf. (2008) Pagliaroli al, Astr. Phys. 31 (2009) SN1987A events ν τ NS ν e ν µ neutronization burst accretion accretion cooling from cooling simulations Time a>er bounce (s) a sensitive probe of the supernova dynamics Hüdepohl et al. PRL 104 (2010)
The explosion mechanism and ν Current simulations : multidimensional, realistic neutrino transport, convection and turbulence, hydrodynamical instabilities (SASI). Neutrinos play a role in revitalizing the shock. first 3D : hints for explosion in 3D not enhanced compared to 2D Hanke et al, 1303.6269 LESA Lepton Number Emission Self- sunstained Asymmetry Tamborra et al, 1402.5418
Supernova observations q Time and energy signal from a supernova explosion. In our galaxy, 1-3 events/century; one explosion/3years at 3 Mpc. q The Diffuse Supernova Neutrino Background ν e ν e ν e Events (10 y) window detector 90 (IH/NH) 9-25 MeV 50 kton scintillator 300 19-30 MeV 440 kton water Cherenkov 30 17-41 MeV 50 kton liquid argon Galais, Kneller, Volpe, Gava, PRD 81(2010). Duan, et al, JPG (2010) q Element nucleosynthesis - r-process, νp-process, ν-nucleosynthesis Focus Issue «Neutrinos and Nucleosynthesis», JP.G (2014)
ν flavour conversion in supernovae neutrinosphere ν e ν-e MSW effect ν µ shock waves (mul.ple MSW) Numerous aspects are being investigated. The situation differs from the case of the sun. Conversion phenomena appear because of q the ν interaction with matter MSW effect and with ν. q dynamical aspects - shock waves and turbulence. Novel conversion phenomena discovered in the last years.
The neutrino evolution as spin precession Schroedinger Equation The Hamiltonian H H ee H* eµ H eµ u H µµ Precession Equation Effective magnetic field The neutrino probabilities : ψ e 2 = Prob(ν e -> ν e ) ψ µ 2 = Prob(ν µ -> ν µ ) Effective spin Neutrino flavour evolution as the precession of an effective spin around an effective magnetic field. P ν e P ν µ
Effects of the νν interaction ν flavour conversion in supernovae Pantaleone, PLB 287 (1992), Samuel, PRD 48 (1993) ν e Survival Probability synchronization bippolar spectral split Distance in SN Neutrino Fluxes at 200 km characteristic imprints Neutrino Energy (MeV) Collective stable and unstable modes in flavor space Duan, Fuller, Qian, Ann. Rev. Nucl. Part. Sci. 60 (2010)
Is mean-field sufficient? Balantekin and Pehlivan, JPG 34 (2007) Cherry et al., PRL108 (2012) - back-scattered neutrino Volpe, Väänänen, Espinoza, PRD87 (2013) -neutrino -antineutrino correlations Vlasenko, Fuller, Cirigliano, PRD89 (2014) Small contributions can be amplified by the non-linearity of the equations. Novel phenomena can arise. ν e ν τ ν µ terms G F 2 dominate : ν trapped Boltzmann transition region? neutrinosphere mean-field app. terms G F important Numerical investigations necessary
Looking across fields Establishing the connection between ν flavour conversion in media and other (many-body) systems such as phonons n p giant resonances metallic clusters 76 Ge 76 As ββ(0ν) 76 Se nuclear collision condensed matter double-beta decay
Beyond the mean-field description Volpe, Väänänen, Espinoza, PRD87 (2013), arxiv: 1302.2374 The mean-field approximation for neutrino density matrix in presence of for example the matter background - MSW effect ρ e electron mean-field Neutrino-antineutrino correlations have to be included in a description beyond the mean-field in presence of a neutrino background. ν-ν pairing correlations the role of neutrino-antineutrino correlations? and of the wrong helicity (m ν /E ν ) contributions?
Current SN observatories Borexino MiniBOONE HALO LVD Baksan Daya-Bay JUNO SK (10 4 ) KamLAND (400) IceCube (10 6 ) Different detection channels available : scattering of anti-ν e with p, ν e with nuclei, ν x with e, p Large detectors -JUNO, GLACIER, Hyper-K, - under study
Unknown ν-properties and supernova ν Neutrino properties leave an imprint on supernova neutrino fluxes and and on nucleosynthesis processes. Among the key unknown properties : q the mass ordering studied either earth matter effects, or the early time signal, or the full time and energy signal of the explosion. q non-standard interactions q sterile neutrinos q CP violation Balantekin, Gava, Volpe, PLB662, (2008). Neutrinos, excellent probes of supernova dynamics
From the early time signal SN ν fluxes at accretion phase Predictions for the time rise in Icecube The hierarchy appear to be distinguishable. Serpico, et al. PRD 85 (2012).
Mass hierarchy from late SN signal Imprint of the mass hierarchy in a water Cherenkov and scintillator detector, if a supernova at 10 kpc explodes. Prediction including the νν interaction and shock wave effects. e + flux (/MeV/s/ton) ν e + p n + e+ inverted hierarchy 29 MeV 15 MeV Gava, Kneller, Volpe, McLaughlin, PRL 103(2009) Time signal (s) Bump (dip) at 3.5 (1) sigma in Super-Kamiokande This can be measured by future large size scintillators or Cherenkov detectors
UHE neutrinos discovery Observation of 37 events (combined 3 years data) at 5.7 σ. ICECUBE collaboration, arxiv : 1405.5303 a new window on the Universe
Mass ordering from atmospheric ν Earth matter effects on the atmospheric neutrino can be used to determine the neutrino mass ordering PINGU, ORCA The ν mass ordering at 3 σ in 3 years ICECUBE coll., arxiv : 1401.2046
Conclusions and perspectives Important progress in neutrino astrophysics in the last years. Novel flavor conversion phenomena uncovered in supernovae but key open questions remain. Astrophysical neutrinos can still bring surprises both on the environments that produce them and for the unknown properties they can unravel.
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