Cristina VOLPE (AstroParticule et Cosmologie -APC)

1. The neutrino mass hierarchy and supernova n Cristina VOLPE (AstroParticule et Cosmologie -APC)

2. nt nt ne ne nm nm Core-collapse supernovae Massive stars (M > 6-8 Msun) emit 1057 neutrinos in 10 seconds, during the gravitational collapse and cooling of the neutron star. Supernova n fluxes from simulations accretion cooling NS accretion cooling Hüdepohl et al. PRL 104 (2010) NS Time after bounce (s) Neutrino fluxes encode imprints of the explosion.

3. Supernova observations • Time and energy signal from a supernova explosion. In our • galaxy, 1-3 events/century; one explosion/yearat 4 Mpc. • The Diffuse Supernova Neutrino Background (DSNB) : • The SN fluxes integrated over cosmologicalredshift. Solar abundance of heavy elements • Element nucleosynthesis • (r-process, np-process, • n-nucleosynthesis). log Y(A) with n-n A Duan, Friedland, McLaughlin, Surman JPG 38 (2010)

4. SN1987A et SN simulations A. Suzuki, J. of Physics, Conf. (2008) SN1987A events (LMC, 50 kpc) see e.g. Pagliaroli et al, Astropart. Phys. 31 (2009) Marek & Janka, ApJ (2009) SN simulations have reached a high degree of complexity : 2D-3D, convection, realistic neutrino transport, SASI. Star radius (km) Time (ms)

5. n flavour conversion in supernovae n-e (MSW) neutrinosphere ne nm shock waves Numerous aspects require investigation. In fact, flavour conversion effects arise because of • the n interaction with matter – MSW effect – and with n. • dynamical aspects - shock waves and turbulence. Novel conversion phenomena discovered in the last years.

6. Hmatter GF re n2 =ne n1 =nm TheMSW effect ne ne Neutrino interaction with matter induces a resonant flavour conversion. e e Wolfenstein PRD (1978) Mikheev and Smirnov, Sov. J. Nucl. Phys. (1985) matter basis flavour basis n2 high density Effective mass n1 vacuum detection on earth MSW resonance location DENSITY

7. TheMSW effect : established Borexino coll, PRL 108 (2012) pep pp MSW solution 7Be n ne Survival Probability 8B n Neutrino Energy (MeV) the beautiful explanation of the « solar neutrino deficit » problem !

8. TheMSW in supernovae The MSW effect is encountered twice : Dighe, Smirnov, PRD62 (2000) n-fluxes at the neutrinosphere Effective mass detection on earth DENSITY vacuum Low r High r SN core FLAVOUR CONVERSION at the H-RESONANCE DEPENDS ON THE NEUTRINO MASS HIERARCHY - either n or anti-n.

9. TheMSW in supernovae • At MSW resonance(s) efficient (adiabatic) conversiondepends on : • stardensityprofile • neutrinoenergy • mixingangles, Dm2 • sign no conversion (non-adiabatic) ne -> ne ne Survival Probability full conversion (adiabatic) ne -> nm Well understood. Distance in the star (a.u.)

10. Theshock wave effects Dasgupta and Dighe, PRD 75 (2007). Kneller, McLaughlin, Brockman, PRD 77 (2008). Profile with shock waves Neutrino conversion in MSW region non-adiabatic t=1s t=1.5s density (g/cm3) anti-ne Survival Prob. inverted hierarchy E=20 MeV adiabatic distance in SN (cm) Time (s) • before the shock - adiabatic conversion It occurs either in ne or in anti-ne channel depending on the hierarchy. • the shock arrives - non-adiabatic • multiple MSW (phase effects) • the shock has gone

11. Turbulence effects Kneller and Volpe, PRD 82 (2010) Profile with turbulence Matter density fluctuations induce multiple MSW resonances and phase effects. Potential (a.u.) distance in SN (cm) Same imprint as shock waves

12. The impact of the n-n interaction Neutrino conversion near the neutrinosphere n-fluxes after 200 km Spectral-split • all neutrinos stick together - synchronization • instability in flavour - bipolar regime 3- ne Survival Probability Neutrino Fluxes Duan,Fuller,Qian PRD74 (2006) 76 (2007), Hannestad, et al. PRD 74 (2006), Galais, Kneller, Volpe JPG 39 (2012) • full or no conversion depending on energy - spectral split 1- 2- Duan, Fuller, Qian, PRD76(2007); Meng and Qian, PRD (2011); Raffelt and Smirnov PRD 76 and PRL (2007); Pehlivan et al, PRD 84 (2011); Galais and Volpe, PRD 84 (2011) Distance in SN Neutrino Energy (MeV)

13. The impact of the n-n interaction • Large matter densities appear to suppress n-n effects • during the accretion phase. • Further work is needed to test some of the approximations, • either geometrical • or inherent to the equations commonly used, such as the • mean-field approximation. see e.g. Chakraborty, et al. PRL 107 (2011) Cherry et al, PRL 108 (2012) Volpe, Vaenaeaenen, Espinoza, 1302.2374 n-anti-n pairing correlations

14. Current SN observatories Borexino Baksan SK (104) LVD Daya-Bay HALO MiniBOONE KamLAND (400) IceCube (106) Different detection channels available : scattering of anti-ne with p, ne with nuclei, nx with e, p

15. The Diffuse Supernova n Background Calculation that treats both the n-n and shock wave effects : Malek et al. PRL (2003) NH IH 928862MEMPHYS (440 kton) 106 99 GLACIER (100 kton) 10598LENA (50 kton) Events/y/22.5 kton/4 MeV Neutrino Energy (MeV) Galais, Kneller, Gava, Volpe, PRD 81 (2010) • Upper limits on DSNB fluxes : • 1.4-1.9 anti-ne /cm2/s • 73-154 ne/cm2/s THE HIERARCHY effect small. Lunardini and Peres, JCAP (2008) Difficult to have unambiguous information seen astrophysical uncertainties (star formation rate).

16. n mass hierarchy with SN n The mass hierarchy signatures studied so far are roughly of three kinds. They exploit : • either earth matter effects with one or two-detectors ; • or the early time signal ; • or the full time and energy signal of the explosion.

17. From the early time signal SN n fluxes at accretion phase Predictions for the time rise in Icecube The hierarchy appear to be distinguishable. Serpico, Chakraborty, Fischer, Hudepohl, Janka, Mirizzi, PRD 85 (2012).

18. From late time and energy signal ON EARTH adiabatic Prediction including the n-n interaction and shock wave effects. inverted hierarchy ne+ p n + e+ non-adiabatic 29 MeV e+ flux (/MeV/s/ton) 15 MeV 15 MeV anti-ne fluxes 29 MeV Gava, Kneller, Volpe, McLaughlin, PRL 103 (2009) . Time signal (s) Energy (MeV) Bump (dip) at 3.5 (1) sigma in Super-Kamiokande if a supernova at 10 kpc explodes...

19. Combining information Vaeaenaenen, Volpe, JCAP 1110 (2011) . (CC+NC) events in HALO-2 (1 kton lead) for a SN at 10 kpc Predictions include nn and n-matter interaction Two-neutron events One-neutron events Detection channels with different energy thresholds allow to identify solutions.

20. Conclusions Simulations of core-collapse supernovae and of neutrino flavour conversion in supernovae are steadilyprogressing. Severalfeaturesestablished but various aspects needs furtherstudies. For the mass hierarchy : - the effect in the DSNB toosmallto bedisentagledfrom astrophysicaluncertainties; - the measurement of the early time riseand late time and energy signal in water Cherenkov or scintillator detectors are promising.

21. Danke. Gracias Thankyou Grazie Life tree Merci

22. nt nt ne ne nm nm Core-collapse supernovae Massive stars (M > 8 Msun) emit 1057 neutrinos in 10 seconds, during the gravitational collapse and cooling of the neutron star. NS Hüdepohl et al.PRL 2010. NS Neutrino fluxes encode imprints of the explosion.