The Role of Neutrinos in Astrophysics

1. The Role of Neutrinos in Astrophysics A.B. Balantekin University of Wisconsin GDR Neutrino Laboratoire Astroparticule et Cosmologie

2. Joint analysis of the solar neutrino data including final SNO salt results along with the most recent KamLAND data Balantekin, et al., PLB 613, 61 (2005)

3. Neutrinos from core-collapse supernovae • Mprog ≥ 8 MSun • E ≈ 1053 ergs ≈ 1059 MeV • 99% of the energy is carried away by neutrinos and antineutrinos with 10 ≤ E ≤ 30 MeV • 1059 Neutrinos!

4. A recent SN remnant (Hubble Space Telescope)

5. X-ray remnant of the SN observed by Chinese in 185 A.D.

6. X-ray remnant of Kepler’s SN (1604)

7. Estimated intensity in the sky of the brightest historical SN (1066) - National Observatory of Turkey, Antalya

8. SN shock wave Chandra

9. SN remnant 99% of the gravitational binding energy of the star Neutron star

10. Recent Accomplishments with neutrinos in astrophysics • Current theoretical prediction of solar neutrino flux and structure of main sequence stars. Solar neutrino measurements precisely confirm the Standard Solar Model. Temperature at the center of the Sun was correctly calculated ab initio to better than 2%. • Recognition of the importance of the neutrino-neutrino interactions on neutrino propagation in dense neutrino systems. Development of the theoretical tools to treat these effects in astrophysical sites. • New theoretical breakthroughs in nucleosynthesis in SN and GRB’s, and role of weak interactions in SN dynamics. • Tritium beta decay mass limit plus knowledge of the large mixing angles • implying that all mass eigenstates are limited, meaning active neutrinos cannot be the dark matter.  This is independently confirmed by the cosmology limits.  Both results had important contributions from theory. • New limits on diffuse SN neutrino flux. Astrophysical uncertainties are now reduced to the point that these searches are primarily testing the neutrino emission per supernova, which is of fundamental interest to nuclear physics.  

11. Recent Accomplishments with neutrinos in astrophysics • Current theoretical prediction of solar neutrino flux and structure of main sequence stars. Solar neutrino measurements precisely confirm the Standard Solar Model. Temperature at the center of the Sun was correctly calculated ab initio to better than 2%. • Recognition of the importance of the neutrino-neutrino interactions on neutrino propagation in dense neutrino systems. Development of the theoretical tools to treat these effects in astrophysical sites. • New theoretical breakthroughs in nucleosynthesis in SN and GRB’s, and role of weak interactions in SN dynamics. • Tritium beta decay mass limit plus knowledge of the large mixing angles • implying that all mass eigenstates are limited, meaning active neutrinos cannot be the dark matter.  This is independently confirmed by the cosmology limits.  Both results had important contributions from theory. • New limits on diffuse SN neutrino flux. Astrophysical uncertainties are now reduced to the point that these searches are primarily testing the neutrino emission per supernova, which is of fundamental interest to nuclear physics.  

12. Neutrinos from SN1987A Adopted from Raffelt

13. iron peak

14. Life stages of a core-collapse supernova Collapse and bounce epoch. S/k ≈ 1 Shock-reheating epoch. S/k ≈ 40 Hot-bubble epoch. S/k ≈ 75 to 500? Possible site of r-process nucleosynthesis

15. Neutrino-driven wind in post-core bounce supernova unshocked matter wind region -sphere injection (heating) region shock-wave Mass outflow rate in the wind region is approximately constant

16. [Fe/H] ≈ -3.1 Observed r-process abundances A > 100 abundance pattern fits the solar abundances well.

17. Yields of r-process nucleosynthesis are determined by neutron-to-proton ratio, n/p Interactions of the neutrinos and antineutrinos streaming out of the core both with nucleons and seed nuclei determine the n/p ratio.  Hence it is crucial to understand neutrino-nucleon cross-sections. Before these neutrinos reach the r-process region they undergo matter-enhanced neutrino oscillations as well as coherently scatter over other neutrinos.  Many-body behavior of this neutrino gas is not understood, but may have significant impact on r-process nucleosynthesis.

18.  How does neutrino mixing and neutrino-neutrino interactions effect the yield of r-process nucleosynthesis? MNS mixing matrix: Atmospheric ’s Reactor ’s, very little contribution from solar ’s Solar neutrinos SuperK, SNO, KamLAND SuperK, K2K Daya Bay Double Chooz

19. Electron Fraction Ye= (ne-- ne+) / nbaryons p = e + e- proton loss rate n = e + e+ neutron loss rate X alpha fraction Weak freeze-out radius: where neutron-to-proton conversion rate is less than the outflow rate dYe/dt = 0

20. dYe/dt = 0 If alpha particles are absent If alpha particles are present Non-zero Xpushes Ye to 1/2 If Ye(0) < 1/2, non-zero X increases Ye. If Ye(0) > 1/2, non-zero X decreases Ye. Alpha effect Fuller, McLauglin, Meyer

21. Can sterile neutrino fix the problem of alpha formation? McLaughlin, Fetter, Balantekin, Fuller, Astropart. Phys., 18, 433 (2003)

22. Neutrino transport in Dense Matter - MSW N : Allowed values of neutrino momenta N distinct commuting SU(2) algebras Smirnov, Fuller and Qian, Pantaleone, McKellar,… Neutrino-Neutrino Interactions

23. For systematic corrections to these equations see Balantekin & Pehlivan, JPG 34, 47 (2007)

24. Nonlinear supernova neutrino and antineutrino flavor transformation with coupled trajectories One finds large-scale, collective flavor oscillations deep in the supernova envelope, even for the atmospheric neutrino mass-squared difference and for allowed values of 13. This is very different from MSW; models for the r-process, explosion, and the neutrino signal could be affected. Normal hierarchy Inverted hierarchy Survival probabilities Duan, Fuller, Carlson, Qian References: • Balantekin & Yuksel, astro-ph/0411159, New J. Phys. 7, 51 (2005) • Fuller, Qian, astro-ph/0505240, PRD 73, 023004 (2006) • Duan, Fuller, astro-ph/0511275, PRD 74, in press. • Duan, Fuller, Carlson, Qian, PRD 74, 105014 (2006); PRL 97, 241101 (2006). • Balantekin & Pehlivan, J. Phys. G 34, 47 (2007).

25. Recall that nucleosynthesis in core-collapse supernovae occurs in conditions which are the isospin-mirror of the conditions for Big-bang nucleosynthesis! Big-Bang: n/p << 1 Core-collapse SN: n/p >>1 In both cases species decouple when the expansion rate exceeds their interaction rate • Two possible hierarchies of neutrino energies: • a) A pronounced hierarchy: E(x) > E(e) > E(e) • b) A less-pronounced hierarchy: E(x) ~ E(e) ~ E(e)

26. 10 MeV 15 MeV 24 MeV 13 MeV 15 MeV Average energies 16 MeV

27. Maen-field approximation for the neutrino gas:

28. Evolution of neutrino fluxes (1/r2 -dependence removed) eexx L51: luminosity in units of 1051 ergs s-1

29. Equilibrium electron fraction 13~ π/10 L51 = 0.001, 0.1, 50 13~ π/20 From Balantekin and Yuksel, New J. Phys. 7, 51 (2005). 13 ~ π/20 with  effect X= 0, 0.3, 0.5 (thin, medium, thick lines)

30. 13~ π/20 with  effect L51 = 0.002, 0.2, 200 L51 = 0.001, 0.1, 50 13~ π/10 13~ π/20 X= 0, 0.3, 0.5 (thin, medium, thick lines)

31. Conclusions • Neutrinos dominate a good part of the physics in a core-collapse supernova. • Understanding the neutrino-nucleon and neutrino-nucleus cross-sections well is of crucial importance. • Neutrinos set the value of the neutron-to-proton ratio in a core-collapse supernova. Hence matter-enhanced neutrino flavor transformation can impact the physics of the explosion and the r-process nucleosynthesis. • Neutrino-neutrino interactions could be the crucial component. At the moment calculation of the neutrino propagation by taking the - interactions (the two-body term) into account is an open, unsolved, problem.