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Exotic Nuclei in Supernova Evolution and R-Process Nucleosynthesis

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Exotic Nuclei in Supernova Evolution and R-Process Nucleosynthesis Exotic Nuclei in supernova evolution and r-process nucleosynthesis Gabriel Martínez Pinedo ENSAR-2 NUSPRASEN workshop, Isolde, CERN, December 06, 2013 Nuclear Astrophysics Virtual Institute Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Outline 1 Electron capture in Core-collapse supernova The role of collectivity beyond N ∼ 40 2 The r-process in neutron star mergers Dynamical ejecta Accretion disk ejecta Observing the r process in mergers 3 Summary Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Weak interactions during collapse R [km] Neutrino Trapping Composition of Iron group and (t ~ 0.1s, cδ ~10¹² g/cm³) RFe heavier nuclei ν e Dominanting process, electron capture on nuclei: ν e − ~ 100 − e +A(Z; N) A(Z 1; N+1)+νe Si Dominated by Gamow-Teller Fe, Ni ν e transitions. Evolution decreases the number M(r) [M ] 0.5 Mhc 1.0 of electrons (Ye) and heavy nuclei Chandrashekhar mass Si−burning shell 2 (Mch = 1:4(2Ye) M ) 15 15 Laboratory 15 Supernova 10 10 10 5 Low−lying Strength 0 Gamow−Teller 5 5 Resonance σ τ+ electron distribution (Z,A) 0 0 (Z−1,A) (Z,A) (Z−1,A) Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Early composition Initially the composition is mainly given by Iron group nuclei. log X 0 9 ­3 50 T = 9.01 GK, ρ = 6.80 × 10 g cm , Ye = 0.433 ­1 40 ­2 ­3 30 ­4 20 ­5 Proton number ­6 10 ­7 0 ­8 0 10 20 30 40 50 60 70 80 Neutron number GMP, M. Liebendörfer, D. Frekers, NPA 777, 395 (2006). Systematic study measured GT strengths Electron capture in Core-collapse supernova A. L. Cole suffice. With increasing density, less sophisticated models like QRPARates may for iron-group nuclei are under control et al. , PRC 86 , 015809 (2012) The r-process in neutron star mergers 7 3 (a) 9 3 (b) 2 ρYe=10 g/cm ρYe=10 g/cm 10 GXPF1a (KB3G) T=3x109 K (KB3G) 5 T=10x109 K EC KB3G EC λ λ / QRPA / EC EC λ 10 (n,p) λ (d,2He) (t,3He) 1 (p,n) T> Summary 1 -1 10 0.5 V V V V Ti Ti Ni Ni Ni Ni Ni Ni Ni Ni Zn Zn Fe Fe Fe Fe Sc Sc Co Co Mn Mn 50 51 50 51 48 48 60 62 64 60 62 64 58 58 64 64 56 56 54 54 45 45 59 59 55 55 Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Late time composition With decreasing Ye the composition moves to more neutron rich nuclei. log X 0 11 ­3 50 T = 17.84 GK, ρ = 3.39 × 10 g cm , Ye = 0.379 ­1 40 ­2 ­3 30 ­4 20 ­5 Proton number ­6 10 ­7 0 ­8 0 10 20 30 40 50 60 70 80 Neutron number GMP, M. Liebendörfer, D. Frekers, NPA 777, 395 (2006). Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Challenge: electron capture beyond N=40 Independent particle treatment g9/2 Unblocked g9/2 Correlations N=40 Finite T f Blocked 5/2 GT p GT f5/2 1/2 p p 1/2 3/2 p3/2 f7/2 neutrons protons f7/2 neutrons protons Core Core Langanke & GMP, RMP 75, 819 (2003) Fuller, ApJ 252, 741 (1982) Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Correlations around N=40: GT+ strength for 76Se The structure of 76Se (Z = 34; N = 42) has been the subject of several studies due to its important for the double beta decay of 76Ge Measured occupation numbers in transfer reactions Schiffer et al, PRL 100, 112501 (2008) Kay et al, PRC 79, 021301(R) (2009) 10 10 EXP EXP SM SM 8 76Se 8 76Se 6 6 4 4 2 2 Proton Occupancy Neutron Occupancy 0 0 p f g p f g Occupation of g9=2 orbital is larger than naive IPM estimates. Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Correlations around N=40: GT+ strength for 76Se Gamow-Teller strength measured in charge-exchange reactions: (d; 2He): Grewe et al., PRC 78, 044301 (2008) 100 10 -3 1.5 = 10 g cm Ye = 0.45 T=2 T=4 T=6 T=8 10 Full 1.0 2 ) Exp.(d, He) -1 (s ec B(GT+) T=2 1 T=4 0.5 T=6 T=8 Full 2 Exp.(d, He) 0.1 0.0 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 Temperature (GK) Excitation energy (MeV) Slow convergence of cross-shell correlations. Thermofield dynamics or finite temperature QRPA models, which consider only 2p-2h (T=2) correlations, do not suffice. What is the role of the N = 40 (Z . 26) island of inversion on electron capture rates? Zhi, Langanke, GMP, Nowacki, Sieja, NPA 859, 172 (2011) Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Most important nuclei Most relevant nuclei are those around N = 50. Shell closure enhances the abundances. Results are sensitive to assumptions about shell closure far from stability. -3 nB (fm ) ∆ 0.3 Z=2 25Msun ∆ Z=2 15Msun ∆ 0.2 Z=5 25Msun ∆ Z=5 15Msun -1 0.1 ∆Z=10 25M > sun ec ∆Z=10 15M λ sun < / -0 > m ec λ 0.5 < -0.1 -0.2 0 -4 -3 10 10 -6 -5 -4 -3 10 10 10 10 -3 nB (fm ) Raduta, et al, PRC 93, 025803 (2016) Sullivan et al, ApJ 816, 44 (2015). Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary r-process astrophysical sites Core-collapse supernova Neutron star mergers Neutrino-winds from Mergers are expected to eject around protoneutron stars. 0:01 M of neutron rich-material. Similar amount ejected from accretion disk. Aspherical explosions, Jets, Magnetorotational Supernova, ... Observational signature: electromagnetic [Winteler et al, ApJ 750, L22 transient from radioactive decay of (2012); Mösta et al, r-process nuclei [KiloNova, Metzger et al arXiv:1403.1230 ] (2010), Roberts et al (2011), Bauswein et al (2013)] Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Neutron star mergers: Short gamma-ray bursts and r-process 30 14.5 30 14.5 14 14 20 13.5 20 13.5 13 13 10 10 12.5 12.5 12 12 0 0 y [km] y [km] 11.5 11.5 11 11 , 78 (2013) −10 −10 10.5 10.5 773 −20 10 −20 10 9.5 9.5 −30 9 −30 9 −30 −20 −10 0 10 20 30 −30 −20 −10 0 10 20 30 x [km] x [km] 12.1235 ms 12.6867 ms 30 14.5 50 14.5 14 40 14 20 13.5 30 13.5 13 10 13 12.5 20 12.5 12 10 0 12 y [km] 11.5 0 y [km] 11.5 11 −10 −10 11 10.5 −20 10.5 −20 10 −30 10 9.5 −40 −30 9.5 9 Bauswein, Goriely, Janka, ApJ −30 −20 −10 0 10 20 30 −50 x [km] 9 13.4824 ms −50 0 50 x [km] 15.167 ms Mergers are expected to eject dynamically around 0:001-0:01 M of neutron rich-material. Impact of weak interactions remains to be understood. Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Neutron star mergers: Short gamma-ray bursts and r-process Fernández & Metzger, 2016 A similar amount of material less neutron rich Ye & 0:2 is expected to be ejected from the disk. Conditions and ejection mechanism depend on central object (neutron star or black hole). Both dynamical and disk ejecta contribute to nucleosynthesis and radioactive electromagnetic transient (kilonova). Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Evolution nucleosynthesis in mergers 528 trajectories r-process stars once electron fermi energy drops below ∼ 10 MeV to allow for beta-decays (ρ ∼ 1011 g cm−3). Important role of nuclear energy production (mainly beta decay). Energy production increases temperature to values that allow for an (n; γ) (γ; n) equilibrium for most of the trajectories. Systematic uncertainties due to variations of astrophysical conditions and nuclear input Mendoza-Temis, Wu, Langanke, GMP, Bauswein, Janka, PRC 92, 055805 (2015) Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Final abundances different mass models FRDM WS3 10-3 10-4 10-5 10-6 abundances at 1 Gyr 10-7 10-8 HFB21 DZ31 10-3 10-4 10-5 10-6 abundances at 1 Gyr 10-7 10-8 120 140 160 180 200 220 240 120 140 160 180 200 220 240 mass number, A mass number, A Mendoza-Temis, Wu, Langanke, GMP, Bauswein, Janka, PRC 92, 055805 (2015) Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Temporal evolution (selected phases) Abundances around 130 mainly determined by fission from material accumulated in superheavy region. Third peak (A ∼ 195) sensitive to masses and beta-decay half-lives. Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Nucleosynthesis in black-hole accretion disk ejecta Accretion disk around compact 4 3.5 object is expected to eject material M) -4 3 with broad Ye distribution 2.5 [Fernández, Metzger, MNRAS 435, 2 1.5 502 (2013)] 1 This material is expected to 0.5 ejecta mass (10 0 contribute to the production of all 0.1 0.15 0.2 0.25 0.3 0.35 0.4 r-process nuclides [Wu et al, MNRAS Ye,5 463, 2323 (2016)] M) 10-2 10-2 solar r abundance solar r abundance FRDM masses FRDM+QRPA 10-3 DZ31 masses 10-3 D3C* 10-4 10-4 10-5 10-5 10-6 10-6 abundances at 1 Gyr abundances at 1 Gyr 10-7 10-7 0 50 100 150 200 250 300 0 50 100 150 200 250 300 mass number, A mass number, A Electron capture in Core-collapse supernova The r-process in neutron star mergers Summary Comparison with metal poor stars Except for elements around Z ∼ 40 (A ∼ 90) disk ejecta produce all r-process nuclides.
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