Neutrino Flavor Transformation : hot neutron stars to the early universe

Transcription

1 Neutrino Flavor Transformation : hot neutron stars to the early universe Neutron Stars and Neutrinos Arizona State University Tempe, AZ April 12, 2010 Geor ge M. Ful l er Depar t ment of Physi cs George M. Fuller Department of Physics & Center for Astrophysics and Space Science University of California, San Diego

2 Neutrino mass physics is a theme common to both Compact Objects (supernovae; neutron stars; holes; etc...) Cosmology (structure formation; dark matter, etc...) Synergy between laboratory/observational neutrino physics and new developments and capabilities in observational astronomy

3 We have an exciting situation in neutrino physics and astrophysics Experiment s are revealing t he propert ies of neut rinos and t his new dat a is driving int erest ing development s in nuclear and part icle ast rophysics. As I will show, t hese ast rophysical development s may feed back on our underst anding of neut rino propert ies. This is classic particle/nuclear astrophysics, with a synergistic coupling of astrophysics and low energy laboratory measurements of physics beyond the Standard Model Willy Fowler might appreciate this...

4 Neutrino Mass: what we know and don t know We know the mass-squared differences: We do not know the absolute masses or the mass hierarchy:

5 Neutrino energy (mass) states are not coincident with the weak interaction (flavor) states The unitary transformation that relates these states in vacuum has 4 parameters (exclusive of Majorana phases) We know 2 of the 4 vacuum 3X3 mixing parameters and we have a good upper limit on a third.

6 Maki-Nakagawa-Sakata matrix 4 parameters

7 Atmospheric Neutrinos δm ev 2 sin 2 θ Solar /KamLaND Neutrinos δm 2 sol ev 2 sin 2 θ The key mixing angle limit on θ 13 sin 2 θ 13 < ( 2σ)

8 My take on this is as follows: (1) What we already know about neutrino mass/mixing has potentially big implications for astrophysics. (2) Working out those implications may allow new insights into nucleosynthesis and unmeasured neutrino properties: e.g., a supernova neutrino signal could help us get at θ 13 and the neutrino mass hierarchy. And, vice versa, what we know about neutrino flavor mixing may give us insights into how supernovae work. Cosmology may give absolute masses --- gives best limits now.

9 Gravitational Collapse of Massive Stars MASS Main Seq. Entropy per baryon Collapse Entropy per baryon Iron core mass Instability Mechanism Fraction of rest mass radiated as neutrinos Neutrino Trapping / Thermal equilibrium 12 to ~ 100 ~ 10 ~ 1 ~ 1.4 Electron capture / Feynman- Chandrasekhar G.R. instab. ~ 10% Iron core mass Yes ~ 100 to ~ 100 ~ 100 NONE pair ~ 10 4 instability ~ 10% C/O burning core Yes ~ 10 4 ~ 1000 to ~ 10 8 no main seq. ~ 1000 NONE Feynman- Chandrasekhar G.R. Instability ~ 5% No

10 Cor e Col l apse Super novae

11 The Core Collapse Supernova Phenomenon is Exquisitely Sensitive to Flavor Changing Processes and New Neutrino Physics: Gravitational collapse results in high electron and ν e Fermi Energies (representing ~ units of e-lepton number); µ/τ charged leptons are absent and the corresponding neutrinos are pair-produced so they carry no net lepton number. Any process that changes flavor ν e ν µ/τ/s will open phase space for electron capture as well as reducing e-lepton number. Later, energy (10% of the core s rest mass) is in seas of active neutrinos of all flavors. Entropy and lepton number transported by neutrinos. Neutron/proton ratio (crucial for nucleosynthesis) determined by electron degeneracy or by charged current neutrino capture:

12 Neutrinos Dominate the Energetics of Core Collapse Supernovae Total optical + kinetic energy, ergs Total energy released in Neutrinos, ergs E GRAV 3 2 G M NS 5 R NS 2 M ergs NS 10 km 1.4M sun R NS Neutrino diffusion time, τ ν 2 s to 10 s Explosion only ~1% of neutrino energy 10% of star s rest mass! L ν 1 2 GM NS ergs s -1 6 R NS τ ν

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14 ordinary MSW evolution of neutrino flavors MSW resonance at neutrino energy E ν = δm2 cos2θ ( 0.02 MeV) δm2 cos2θ 2( A + B) ev g cm -3 ρ( Y e + Y ν ) At a given location expect only neutrinos in a narrow energy range to experience large flavor mixing while anti-neutrino mixing is suppressed. With the small measured neutrino mass-squared differences we expect significant flavor conversion only at low densities. sin 2 2θ M λ mfp >>res. width incoherent λ mfp <<res. width coherent time/position - dependent mixing angle and mass-states ν e = cosθ M ( t)ν 1 t ( ) + sinθ M t ( )ν 2 t ( ) ν τ = sinθ M ( t)ν 1 ( t) + cosθ M ( t)ν 2 ( t) E ν (MeV)

15 Coherent Flavor Evolution for Neutrino i neutrino-electron charged current forward exchange scattering neutrino-neutrino neutral current forward scattering Neutrino Self Coupling - the source of nonlinearity Effects beyond the mean field? Balantekin & Pehlivan (2007) Friedland & Lunardini (2003)

16 now self-consistently couple flavor evolution on all neutrino trajectories... Anisotropic, nonlinear quantum coupling of all neutrino flavor evolution histories

17 Neutrino flavor evolution in core collapse supernovae (numerical simulations/analyses with coupled trajectories) Huaiyu Duan (UCSD/INT), George M. Fuller (UCSD) Joseph A. Carlson (LANL),Yong-Zhong Qian (U. Minn.) Simultaneous flavor transformation of neutrinos and antineutrinos with dominant potentials from neutrino-neutrino forward scattering, G.M. Fuller & Y.-Z. Qian, Phys. Rev. D 73, (2006) Collective neutrino flavor transformation in supernovae, H. Duan, G.M. Fuller, & Y.-Z. Qian, Phys. Rev. D 74, (2006) Coherent Development of Neutrino Flavor in the Supernova Environment, H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 97, (2006) Simulation of coherent nonlinear neutrino flavor transformation in the supernova environment: Correlated neutrino trajectories, H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. D 74, (2006) Analysis of Collective Neutrino Flavor Transformation in Supernovae, H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. D 75, (2007) A Simple Picture for Neutrino Flavor Transformation in Supernovae, H. Duan, G.M. Fuller, & Y.-Z. Qian, Phys. Rev. D 76, (2007) Neutrino Mass Hierarchy and Stepwise Spectral Swapping of Supernova Neutrino Flavors, H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 99, (2007) Flavor Evolution of the Neutronization Neutrino Burst from an O-Ne-Mg Core Collapse Supernova, H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 100, (2008) Stepwise Spectral Swapping with Three Neutrino Flavors, H. Duan, G.M. Fuller, Y.-Z. Qian, Phys. Rev. D 77, (2008) Simulating Nonlinear Neutrino Flavor Transformation, H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Computational Science & Discovery, 1, (2008)

18 Some other recent work on neutrino flavor evolution in core collapse supernovae S. Pastor & G.C. Raffelt, Phys. Rev. Lett. 89, (2002) A. Friedland, B.H.J. McKellar, I. Ocuniewicz, Phys. Rev. D 73, (2006) R. F. Sawyer, Phys. Rev. D 72, (2005) G.C. Raffelt & A.Y. Smirnov, hep-ph/ S. Hannestad, G.C. Raffelt, G. Sigl, & Y.Y.Y. Wong, Phys. Rev. D 74, (2006) astro-ph/ (the flavor pendulum ) G.C. Raffelt & G. Sigl astro-ph/ J.P. Kneller, G.C. McLaughlin, & J. Brockman, astro-ph/ A.B. Balantekin & H. Yuksel, New J. Phys. 7, 51 (2005) A. Friedland and C. Lunardini, J. High Energy Phys. 10, 043 (2003) A. Dolgov, S. Hansen, S. Pastor, S. Petcov, G. Raffelt, P. Semikoz hep-ph/ K. Abazajian, J. Beacom, N. Bell astro-ph/ Ot her gr oups now have mul t i - angl e codes... A. Esteban-Pretel, S. Pastor, R. Tomas, G.C. Raffelt, G. Sigl, astro-ph/ G. Fogli, E. Lisi, A. Marrone, A. Mirizzi, hep-ph/

19 A great deal of work has now been done on this problem by many groups around the world. There is now a huge literature on this topic. See review on Collective Neutrino Oscillations: H. Duan, G. M. Fuller, & Y.-Z. Qian, hep-ph/

20 Results of Large-Scale Numerical Calculations In the sample numerical calculations that follow we have taken: The neutrino mass-squared difference to be The effective 2 X 2 vacuum mixing angle to be either for the NORMAL MASS HIERARCHY for the INVERTED MASS HIERARCHY The neutrino energy luminosities to be the same for all species and either or as indicated.

21 neutrinos antineutrinos angle-averaged energy spectra cosine of emission angle NORMAL MASS HIERARCHY r 6 radius in units of 10 6 cm

22 neutrinos antineutrinos angle-averaged energy spectra cosine of emission angle NORMAL MASS HIERARCHY r 6 radius in units of 10 6 cm

23 neutrinos antineutrinos angle-averaged energy spectra cosine of emission angle INVERTED MASS HIERARCHY r 6 radius in units of 10 6 cm

24 cosine of ν trajectory angle wrt. normal to n.s. surface normal mass hierarchy inverted mass hierarchy survival probability Spectral Swap consequences of neutrino mass and quantum coherence in supernovae H. Duan, G. M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 97, (2006) astro-ph/

25 The ν e - ν µ/τ Spectral Swap - a mass hierarchy signal? survival probability P νν cosi ne of neut r i no emi ssi on angl e nor mal mass hi er ar chy her e spect r al swap ener gy E C decr eases wi t h decr easi ng θ V i nver t ed mass hi er ar chy neut r i no ener gy neut r i no ener gy swap has its origin in nonlinear neutrino self- coupling H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 99, (2007)

26 O- Ne- Mg Cor e Col l apse Super novae The progenitors of these events are stars in the mass range K. Nomoto, Astrophys. J., 277, 791 (1984); 322, 206 (1987) Post-collapse, these objects have a very steep matter density profile above the neutron star and behind the (viable) shock. Modeling flavor transformation in the neutronization burst requires a full 3X3 mixing treatment with neutrino self-coupling. We find a sequence of neutrino spectral swaps which, if detected, could identify the neutrino burst as originating in an O-Ne-Mg event instead of an ordinary Fe-core-collapse! H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 100, (2008) C. Lunardini, B. Mueller, H.-Th. Janka, Phys. Rev. D 78, (2008)

27 Full 3X3 treatment (with both atmospheric and solar mass-squared differences) of the neutronization burst from an O-Ne-Mg core collapse: succession of spectral swaps Distinctive pattern could tell us whether SN is an Fe-core or an O-Ne-Mg core collapse: H. Duan, G.M. Fuller, J. Carlson, Y.-Z. Qian, Phys. Rev. Lett. 100, (2008) squared-amplitude

28 to this end... open issues Non-Spherical geometries... 3-D hydro e.g., the SASI and late re-heating Blondin & Mezzacappa Nature 445, 58 (2007) Inhomogeneous matter/neutrino environments, e.g., what are the effects of inhomogeneities like turbulence or the shock on the neutrino signal, anisotropic neutrino emission? Friedland & Gruzinov (2006); Gava et al. (2009) Galais, Kneller, Volpe, & Gava (2009); review by H. Duan & J. Kneller (2009) Full 3X3 flavor transformation in realistic environments, multi-angle, phase averaging - necessary e.g., A. Friedland hep-ph/ (2010) Extension to regime where scattering-induced de-coherence is significant: the full Quantum Kinetic Equations. Abazaj i an, Ful l er, Pat el ( 2001) ; St r ack & Bur r ows (2005) Cardall (2007, 2009); Kishimoto & Fuller (2008)

29 CONCLUSIONS The experimental revolution in neutrino physics has given us some of the mass/mixing properties of the neutrinos. Modelers should include this physics in models of core collapse supernovae and in the early universe. Neutrino self coupling can alter neutrino flavor evolution in SN, ultimately causing large-scale flavor conversion deep in the supernova envelope, despite the small measured neutrino mass-squared differences. MSW-based analyses are inadequate. This could affect neutrino-heated nucleosynthesis and the neutrino signal. Neutrino self coupling-induced flavor collective modes may produce distinctive signatures which could allow a supernova neutrino signal to give us the neutrino mass hierarchy and θ 13 as well as give us an observational window on the deep interior of the core and distinguish between Fe-core collapse and O-Ne-Mg core collapse.