Neutrinos and explosive nucleosynthesis

Transcription

1 Neutrinos and explosive nucleosynthesis Gabriel Martínez-Pinedo Microphysics in computational relativistic astrophysics June 22, 2011

2 Outline 1 Introduction 2 Neutrino-matter interactions 3 Nucleosynthesis in proton-rich ejecta The νp-process Collective neutrino oscillations 4 Summary

3 Neutrino emission from the proto-neutron star T ~ 1/R ν, ν, ν, ν ν µ µ τ τ e Neutrino spectra and luminosities important for: Energy (MeV) Neutrino detection from SN1987A Kamiokande II IMB Time (seconds) Nucleosynthesis in neutrino driven wind: νp-process and r-process(?). Neutrino-nucleosynthesis: production of some key isotopes, 11 B, 19 F, 15 N, 138 La and 180 Ta, by neutral current spallation reactions and charged-current neutrino absorption in the ONe, C and He layers of the star. Possibility of having an r-process in the He layer at low metalicities [Banerjee et al., PRL 106, (2011)] Neutrino oscillations (collective, MSW, vacuum) Neutrino detection on Earth

4 Neutrino-driven winds and r-process Woosley et al, ApJ 433, 229 (1994), suggested neutrino-driven winds as the r-process site. High entropy conditions not confirmed by any other group, Takahashi, Witti, Janka, A&A 286, 857 (1994)... Abundance Mass Number

5 Influence of neutrinos on nucleosynthesis Main processes: + n p + e + p n + e + Neutrino interactions determine the proton to neutron ratio, the ejecta are proton rich if: ɛ νe ɛ νe < 4(m n c 2 m p c 2 ) 5.2MeV Early times (up to 1-2 seconds): proton-rich ejecta (νp-process). Later times: neutron-rich ejecta (r-process)?? average energy [MeV] Marek & Janka, ApJ 694, 664 (2009) time [ms] ν µ, ν τ 2.5 MeV

6 Neutrino-matter interactions Charge-current processes: + n p + e (Bruenn 1985, Horowitz 2002) + A(Z) A(Z + 1) + e (Bruenn 1985, Juodagalvis et al., 2010) + p n + e + (Bruenn 1985, Horowitz 2002) Elastic scattering processes: ν + {n, p} {n, p} + ν (Bruenn 1985, Horowitz 2002) ν + A A + ν (Bruenn 1985, Bruenn & Mezzacappa 1997) Inelastic Scattering processes: ν + e ± ν + e ± (Mezzacappa & Bruenn 1993) Pair processes: ν + ν e + + e (Bruenn 1985) ν + ν + N + N N + N (Hannestad & Raffelt 1998) Additional processes: ν + ν ν + ν (Buras et al 2003) + ν µ,τ + ν µ,τ (Buras et al 2003) ν + A A + ν (Langanke et al 2008) + {d, t, 3 He} { 2 He, 3 He, 3 Li} + e (Nakamura et al. 2002) + {d, t, 3 He} { 2 n, 3 n, t} + e + (Nakamura et al. 2002, Arcones et al 2008) ν + {d, t, 3 He} {d, t, 3 He } + ν (Nakamura et al. 2002, O Connor et al 2007) ν + N + N N + N + ν (Hannestad & Raffelt 1998, Bacca et al 2009) + A(Z) A(Z 1) + e +

7 Long term evolution neutrino luminosities and average energies Long-term simulations of the collapse and explosion of an 8.8 M ONeMg core, L [10 52 erg s -1 ] 4 L/10 Accretion Phase Cooling Phase ν µ/τ <ε> [MeV] L [10 52 erg s -1 ] <ε> [MeV] Time after bounce [s] L/10 Accretion Phase Cooling Phase ν µ/τ Fischer et al, A&A 517, A80 (2010) Time after bounce [s] Hüdepohl et al., PRL 104, (2010)

8 Ejecta are always proton rich 0.6 Electron Fraction, Y e Y e = Time After Bounce [s] Fischer et al, A&A 517, A80 (2010)

9 Neutrino spectra formation (Raffelt 2001; Keil, Raffelt & Janka 2003)

10 electron neutrino and antineutrino opacities Based on detailed information from Boltzmann transport long term simulations of ONeMg core. 1/λ [1/km] Radius, r [km] 1 s after bounce Fischer, GMP, Hempel, Liebendörfer, in preparation anti IS,νn IS,νp ν abs νν ννnn νe ± Radius, r [km]

11 electron neutrino and antineutrino opacities Based on detailed information from Boltzmann transport long term simulations of ONeMg core. 1/λ [1/km] Radius, r [km] 7 s after bounce Fischer, GMP, Hempel, Liebendörfer, in preparation anti Radius, r [km] IS,νn IS,νp ν abs νν ννnn νe ±

12 Impact of neutrino interactions on proton-rich ejecta Once neutrino interactions are consistently included in the nucleosynthesis network, nuclei with A > 64 are produced Without ν With ν Yi/Yi, Mass Number A

13 The νp-process Without neutrino interactions proton-rich ejecta form N = Z iron-group nuclei with A < 64. However, nucleosynthesis occurs at the presence of substantial neutrino fluxes. 65 As (p, γ) S = 90(85) kev p 64 Ge β s 64 Ga

14 The νp-process Without neutrino interactions proton-rich ejecta form N = Z iron-group nuclei with A < 64. However, nucleosynthesis occurs at the presence of substantial neutrino fluxes. Antineutrino absorption and expansion time scales are similar ( 1 s) Neutrinos speed-up the matter flow + p e + + n n + 64 Ge 64 Ga + p 64 Ga + p 65 Ge... These reactions constitute the νp-process C. Fröhlich, et al., PRL 96, (2006) 65 As 64 Ge ( n,p) ~ 10 ms 66 As 65 Ge 64 Ga (p, γ) (p, γ)

15 The νp-process Without neutrino interactions proton-rich ejecta form N = Z iron-group nuclei with A < 64. However, nucleosynthesis occurs at the presence of substantial neutrino fluxes. Antineutrino absorption and expansion time scales are similar ( 1 s) Neutrinos speed-up the matter flow + p e + + n n + 64 Ge 64 Ga + p 64 Ga + p 65 Ge... These reactions constitute the νp-process C. Fröhlich, et al., PRL 96, (2006) Mi/(M ej Xi, ) Cu Se Kr Zn GaGe Br Rb As Sr Mass number A Y Mo Zr Nb Trajectories from supernova simulation (Janka) Ru Pd Rh Cd

16 Collective neutrino oscillations νp-process nucleosynthesis is sensitive to collective neutrino oscillations. Changes in neutrino spectra depend on neutrino fluxes and hierarchy. Fogli, et al, PRD 78, (2008) Flux (a.u.) Initial neutrino and antineutrino fluxes Dasgupta et al, PRL 103, (2009) Antineutrinos IH Neutrinos IH 0.2 ν x ν x E (MeV) E (MeV) < E e > = 10 MeV < E x > = 24 MeV < E e > = 15 MeV < E x > = 24 MeV NH NH Flux (a.u.) ν x E (MeV) E (MeV) Inverted hierarchy. ν x Energy [MeV] Energy [MeV] Collective-neutrino oscillations may result in a harder antineutrino spectrum and larger antineutrino absorption rate on protons.

17 Schematical treatment of spectral split 0.08 f νe f νµ, τ Spectra [a. u.] Energy [MeV] f νe Spectra [a. u.] f νµ, τ Energy [MeV] Spectra from Buras et al. ApJ 447, 1049 (2006).

18 Enhancement of antineutrino absorption rate Ratio, Γ Split Energy, E s [MeV]

19 Impact on nucleosynthesis Mi/(M ej Xi, ) Se Kr Ge Ga As Sr Rb Br Mo Zr Y Ru Nb Pd Cd 10 1 Ratio Zn Mass number GMP, Ziebarth, Fischer, Langanke, arxiv:

20 Summary Neutrino-driven winds produce proton-rich ejecta that constitute the site for the νp-process. The νp-process can explain the solar abundances of light p nuclei ( 92,94 Mo, 96,98 Ru). Collective neutrino oscillations can have a strong impact in the nucleosynthesis. The dominating opacity channel at late times for all (anti)neutrino species is elastic scattering on nucleons resulting in very similar spectra. Neutron rich ejecta are not possible at late times.