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Astrophysical Neutrinos

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Astrophysical Neutrinos ISAPP 2019, Heidelberg,Crab Nebula 28 May –4 June 2019 Astrophysical Neutrinos Georg G. Raffelt Max-Planck-Institut für Physik, München, Germany Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Where do Neutrinos Appear in Nature? Nuclear Reactors Sun Supernovae (Stellar Collapse) Particle Accelerators SN 1987A Earth Atmosphere Astrophysical (From Cosmic Rays) Accelerators Cosmic Big Bang 3 Earth Crust (Today 336 n/cm ) (Natural Radioactivity) Indirect Evidence Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Grand Unified Neutrino Spectrum Christian Spiering Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Neutrinos from the Sun Helium Reaction- Energy chains 26.7 MeV Solar radiation: 98 % light (photons) 2 % neutrinos At Earth 66 billion neutrinos/cm2 sec Hans Bethe (1906-2005, Nobel prize 1967) Thermonuclear reaction chains (1938) Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Sun Glasses for Neutrinos? 8.3 light minutes Several light years of lead needed to shield solar neutrinos Bethe & Peierls 1934: … this evidently means that one will never be able to observe a neutrino. Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 First Detection (1954 – 1956) Clyde Cowan Fred Reines (1919 – 1974) (1918 – 1998) Nobel prize 1995 Detector prototype Anti-Electron n Cd g Neutrinos 3 Gammas from 흂 g 퐞 p in coincidence Hanford Nuclear Reactor e+ e− g Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Heisenberg 1936 Instead [of protons and neutrons] Pauli's hypothetical 'neutrinos' should contribute substantially to the penetrating radiation. This is because in each shower ... neutrinos should be generated which then would lead to the generation of small secondary showers. The cross section for the generation of these secondary showers would likely not be much smaller than 10-26 cm². Contrary to the low- energy neutrinos from decay one should be able to detect the energetic neutrinos from cosmic rays via their interactions. Werner Heisenberg Zur Theorie der Schauerbildung in der Höhenstrahlung Zeitschrift für Physik 101 (1936) 533 Georg Raffelt, MPI Physics, Munich Slide adapted from Christian SpieringAstrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Detection of First Atmospheric Neutrinos 1965 • Kolar Gold Field (KGF) Collaboration Japan-India-UK group, 7500 mwe Plastic scintillator, Flash tubes • Chase-Witwatersrand-Irvine (CWI) Coll. Mine in South Africa, 8800 mwe Liquid scintillator, Horizontal tracks First neutrino sky map with celestial coordinates of 18 Kolar Gold Field neutrino events (Krishnaswamy et al. 1971) Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 East Rand Neutrino Plaque Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Atmospheric Neutrinos T. Kajita Univ. Tokyo 2015 Neutrino 1998 Takayama, Japan Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 First Measurements of Solar Neutrinos Inverse beta decay of chlorine 600 tons of Perchloroethylene Homestake solar neutrino observatory (1967–2002) Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Results of Chlorine Experiment (Homestake) ApJ 496:505, 1998 Theoretical Expectation Average Rate Average (1970-1994) 2.56 0.16stat 0.16sys SNU (SNU = Solar Neutrino Unit = 1 Absorption / sec / 1036 Atoms) Theoretical Prediction 6-9 SNU “Solar Neutrino Problem” since 1968 Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Neutrino Flavor Oscillations Pontecorvo & Gribov (1968) on “Solar Neutrino Problem“ • Neutrinos are superpositions of “mass eigenstates” 휈푒= +cos Θ 휈1 + sin Θ 휈2 휈휇= −sin Θ 휈1 + cos Θ 휈2 • Different speed of propagation 훿푚2 • Phase difference 퐿 causes flavor oscillations 2퐸 • Similar to “optical activity” of light propagation Bruno Pontecorvo (1913–1993) Probability 휈푒 → 휈휇 sin2(2휃) z 2 Oscillation 4휋퐸 퐸 eV Vladimir Gribov = 2.5 m Length 훿푚2 MeV 훿푚 (1930–1997) Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Three Flavor Mixture of Neutrinos Small “1-3-Mixing” since 2012 measured at reactor-experiments (Double-Chooz, Daya Bay, Reno) 2% 30% 41% Atmospheric Neutrinos 57% 2 2 2 푚3 − 푚2 ≈ 2400 meV 68% 47% Solar Neutrinos 23% 2 2 2 푚2 − 푚1 ≈ 75 meV 20% 12% Latest details, e.g., at http://www.nu-fit.org/ Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Neutrinos and the Stars • Strongest local neutrino flux • Long history of detailed measurements • Crucial for flavor oscillation physics • Resolve solar metal abundance problem in future? Sun • Use Sun as source for other particles (especially axions) • Neutrino energy loss crucial in stellar evolution theory • Backreaction on stars provides limits, e.g. neutrino magnetic dipole moments Globular Cluster • Collapsing stars most powerful neutrino sources • Once observed from SN 1987A • Provides well-established particle-physics constraints • Next galactic supernova: learn about astrophyiscs of core collapse Supernova 1987A • Diffuse Supernova Neutrino Background (DSNB) is detectable Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Equations of Stellar Structure Assume spherical symmetry and static structure (neglect kinetic energy) Excludes: Rotation, convection, magnetic fields, supernova-dynamics, … Hydrostatic equilibrium 푟 Radius from center 푃 Pressure 푑푃 퐺푁푀푟휌 = − 푑푟 푟2 퐺푁 Newton’s constant Energy conservation 휌 Mass density 푀푟 Integrated mass up to r 푑퐿푟 = 4휋푟2휖휌 퐿푟 Luminosity (energy flux) 푑푟 휖 Local rate of energy Energy transfer generation [erg g−1s−1] 2 4 4휋푟 푑 푎푇 휖 = 휖nuc + 휖grav − 휖휈 퐿 = 푟 3휅휌 푑푟 휅 Opacity −1 −1 −1 Literature 휅 = 휅훾 + 휅c • Clayton: Principles of stellar evolution and 휅훾 Radiative opacity −1 nucleosynthesis (Univ. Chicago Press 1968) 휅훾휌 = 휆훾 Rosseland • Kippenhahn & Weigert: Stellar structure 휅c Electron conduction and evolution (Springer 1990) Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Virial Theorem and Hydrostatic Equilibrium 푑푃 퐺푁푀푟휌 Hydrostatic equilibrium = 푑푟 푟2 푅 푅 3 ′ 3 퐺푁푀푟휌 Integrate both sides 푑푟 4휋푟 푃 = − 푑푟 4휋푟 2 0 0 푟 푅 L.h.s. partial integration 2 tot −3 푑푟 4휋푟 푃 = 퐸grav with 푃 = 0 at surface 푅 0 2 Monatomic gas: 푃 = 푈 tot 1 tot 3 푈 = − 퐸grav (U density of internal energy) 2 Average energy of single 1 〈퐸 〉 = − 〈퐸 〉 “atoms” of the gas kin 2 grav Virial Theorem: Most important tool to study self-gravitating systems Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Dark Matter in Galaxy Clusters A gravitationally bound system of many particles obeys the virial theorem 2 퐸kin = −〈퐸grav〉 2 푚푣 퐺푁푀푟푚 2 = 2 푟 2 −1 푣 ≈ 퐺푁푀푟 푟 Velocity dispersion from Doppler shifts and geometric size Total Mass Coma Cluster Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Virial Theorem Applied to the Sun 1 Virial Theorem 퐸 = − 〈퐸 〉 kin 2 grav Approximate Sun as a homogeneous sphere with 33 Mass 푀sun = 1.99 × 10 g 10 Radius 푅sun = 6.96 × 10 cm Gravitational potential energy of a proton near center of the sphere 3 퐺푁푀sun푚푝 퐸grav = − = −3.2 keV 2 푅sun Thermal velocity distribution 3 1 퐸 = 푘 푇 = − 〈퐸 〉 kin 2 B 2 grav Central temperature from Estimated temperature standard solar models 7 푇 = 1.1 keV 푇c = 1.56 × 10 K = 1.34 keV Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Self-Regulated Nuclear Burning 1 Virial Theorem: 퐸 = − 〈퐸 〉 kin 2 grav Small Contraction Heating Increased nuclear burning Increased pressure Expansion Additional energy loss (“cooling”) Loss of pressure Main-Sequence Contraction Star Heating Increased nuclear burning Hydrogen burning at nearly fixed T Gravitational potential nearly fixed: 퐺N푀 푅 ∼ constant 푅 ∝ 푀 (More massive stars bigger) Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Degenerate Stars (“White Dwarfs”) 1 3 Assume temperature very small 0.6 푀⊙ 푅 = 10,500 km 2푌 5 3 No thermal pressure 푀 푒 Electron degeneracy is pressure source (푌 electrons per nucleon) 푒 Pressure ~ Momentum density Velocity 3 3 • Electron density 푛푒 = 푝F 3휋 For sufficiently large stellar mass 푀, • Momentum 푝 (Fermi momentum) electrons become relativistic F • Velocity 푣 ∝ 푝 푚 • Velocity = speed of light F 푒 5 5 3 5 3 −5 • Pressure • Pressure 푃 ∝ 푝F ∝ 휌 ∝ 푀 푅 −3 4 4 3 4 3 −4 • Density 휌 ∝ 푀푅 푃 ∝ 푝F ∝ 휌 ∝ 푀 푅 Hydrostatic equilibrium No stable configuration 푑푃 퐺N푀푟휌 = − 푑푟 푟2 With 푑푃 푑푟 ∼ −푃/푅 we have −1 2 −4 푃 ∝ 퐺N푀휌푅 ∝ 퐺N푀 푅 Inverse mass radius relationship Chandrasekhar mass limit −1 3 2 푅 ∝ 푀 푀Ch = 1.457 푀⊙ 2푌푒 Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Degenerate Stars (“White Dwarfs”) 1 3 0.6 푀⊙ 푅 = 10,500 km 2푌 5 3 푀 푒 (푌푒 electrons per nucleon) For sufficiently large stellar mass 푀, electrons become relativistic • Velocity = speed of light • Pressure 4 4 3 4 3 −4 푃 ∝ 푝F ∝ 휌 ∝ 푀 푅 No stable configuration Chandrasekhar mass limit 2 푀Ch = 1.457 푀⊙ 2푌푒 Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos, ISAPP 2019, 28 May–4 June 2019 Hydrogen Burning PP-I Chain CNO Cycle Georg Raffelt, MPI Physics, Munich Astrophysical Neutrinos,
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