Nucleosynthesis Process. Ba: s-process Ag, Eu: r-process

Transcription

1 Nucleosynthesis Process Ba: s-process Ag, Eu: r-process Ba Ag Eu

2 Nucleosynthesis Process Ba: s-process Ag, Eu: r-process Ba Ag Eu

3 Nucleosynthesis Process Ba: s-process Ag, Eu: r-process Ba Ag Eu

4 0 Metal-poor stars [Zr/Eu] a Δ log ε Relative log log ε Sneden et al., Annu. Rev. Astro. 2008, 46, 241 [Pd/Eu] Individual stellar abundance offsets with respect to Simmerer et al. (2004) b Montes et al. ApJ 2007, 671, [Ba/Eu] < 0 R-process rich [Fe/H] < -2.5 Metal poor (old stars) Atomic number CS : Sneden et al. (2003) HD : Westin et al. (2000) BD : Cowan et al. (2002) CS : Hill et al. (2002) HD : Ivans et al. (2006) HE : Frebel et al. (2007) [Sr/Eu] [Sr/Eu] [Ag/Eu] [Eu/Fe] 0.5 HD HD HD [Eu/Fe] BD CS CS

5 [A/B] = log 10 (Y A /Y B )-log 10 (Y A /Y B ) solar [Ba/Eu] < 0 R-process rich [Fe/H] < -1 Metal poor (old stars) Z=38 Z=39 Z=56 Z=57 Z=40 Z=58 Solar r-process ratio Z=46 Z=60 Z=47 Z=62

6 Metal-poor not r-process enriched stars Qian&Wasserburg Phys. Rep. 2007, 442, HD ([Fe/H] = -2.77, Honda et al. 2006) log ε (Z) -1-2 Y Mo Nb Ru Pd Ag Ce [Fe/H] = -2.8 [Ba/Eu] = -0.5 Pr -3 Eu translated solar r-pattern (Arlandini et al. 1999) Atomic Number (Z) Light Element Primary Process LEPP abundance pattern

7 proton number Ni Co Fe (n,!) (" ) (" + ) Zn Cu Ge Ga Se As Kr Br Sr Rb Zr Y neutron number HD r Solar s p r

8 Nucleosynthesis processes Most of the heavy elements (Z>30) are formed in neutron capture processes, either the slow (s) or rapid (r) process p process Frohlich et al. 2006, Pruet et al. 2006, Wanajo et al νp process r process Mass known Half-life known nothing known protons rp process stellar burning Big Bang Cosmic Rays neutrons s process Light element primary process LEPP Travaglio et al Montes et al Solar = s-process + r-process + light element primary process

9 nuclear matter nuclei Nucleosynthesis in ν-driven winds R [km] Neutrino Cooling and Neutrino Driven Wind (t ~ 10s) ν e,µ,τ,ν e,µ,τ Qian&Woosley 1996 Entropy S L -1/6 ϵ -1/3 Rns -2/3 Mns Expansion timescale R ~ 10 ns R ν 3 2 PNS 1.4 α,n n, p 9 α,n, Be, C, seed 12 Ni α r process? Si He O 3 ν e,µ,τ,ν e,µ,τ M(r) [M ] τ L -1 ϵ -2 Rns Mns Lν e /Lν e =1 Lν e /Lν e =1.1 Woosley et al Arcones et al Hüdepohl et al Fischer et al Electron fraction Ye r in a collapsing stellar iron core on the way to the ht) visualize the physical conditions at the onset of of the prompt shock, shock stagnation νe+n p+e and revival rino-driven wind of the newly formed neutron star, νe+p n+e n the upper parts of the figures the dynamical state + The lower parts of the figures contain information

10 ν-driven wind simulation shock Radius [cm] reverse shock Entropy [kb/nuc] neutron star time [s] Arcones et al. 2007

11 ν-driven wind simulation shock 15M (slow contraction) Radius [cm] reverse shock 25M 15M 10M 15M (slow contraction) 25M neutron star 10M 15M time [s]

12 Nucleosynthesis in ν-driven winds Arcones&Montes, arxiv: no heavy r-process nuclei some LEPP nuclei produced Roberts et al. NIC_XI_165 Sr-Y-Zr-Nb produced (slow contraction) Light element primary process pattern No major difference as a function of mass progenitor for same neutron star contraction evolution Integrated abundances based on the neutrino-driven wind simulations

13 Nucleosynthesis and electron fraction neutron-rich proton-rich Initial composition determined by nuclear statistical equilibrium alphas protons neutrons At high temperatures only n, p, alphas exist seed T9=8

14 Nucleosynthesis and electron fraction neutron-rich proton-rich Initial composition determined by nuclear statistical equilibrium alphas At high temperatures only n, p, protons seed neutrons alphas exist Seed nuclei created by the time T9 5 T9=5

15 Nucleosynthesis and electron fraction neutron-rich proton-rich Initial composition determined by nuclear statistical equilibrium alphas At high temperatures only n, p, protons neutrons seed alphas exist Seed nuclei created by the time T9 5 Charged-particle freeze-out occurs between T9 2-3 Formation of heavier nuclei depends T9=2 produced by the νp-process on neutron-to-seed ratio and on proton-to-seed ratio after freeze-out

16 Nucleosynthesis and electron fraction neutron-rich proton-rich Abundance pattern is robust to local variations of the electron fraction Sr Zr Cd Y r-process elements can only be created with extreme Ye values Ba Production of heavy elements

17 Nucleosynthesis in proton-rich ν-driven winds Superposition of trajectories 0.5 < Ye < 0.65 following Hüdepohl et al. (2009) Limit assuming that every supernova ejects the same amount of matter with the same isotopic composition Arcones&Montes, arxiv: p-nuclei created Abundance pattern is robust to local variations of the electron fraction LEPP pattern observed in old metal-poor star can be explained but... The LEPP component of Travaglio et al requires s-only isotopes

18 Nucleosynthesis in neutron-rich ν-driven winds Superposition of trajectories with 0.5 > Ye > 0.45 LEPP pattern observed in old metalpoor stars can be explained but... Elemental pattern is rather sensitive to electron fraction evolution Overproduction of A=90 nuclei (Hoffman et al. 1996)

19 Conclusions First comparison of the light element primary process pattern observed in metal-poor stars and nucleosynthesis in realistic neutrino driven-wind simulations Electron fraction has an important effect on final abundances and depends on the uncertain composition and interaction in the outer layers of the proton-neutron star Abundance pattern can be reproduced by neutron and proton -rich winds Proton-rich winds show a rather robust pattern but produce p-nuclei and not in enough quantities Neutron-rich winds overproduce A=90 nuclei A combination of both types of winds is likely and may be able to explain the LEPP solar system contribution

20 Nucleosynthesis and neutrino luminosity