Explosive nucleosynthesis of heavy elements
Gabriel Martínez Pinedo
Computational Challenges in Nuclear and Many-Body Physics Nordita, Stockholm, September 15 - October 10, 2014
Nuclear Astrophysics Virtual Institute Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Outline
1 Introduction
2 Nucleosynthesis in supernova neutrino-driven winds
3 Nucleosynthesis in compact-object mergers
4 Summary Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Signatures and nucleosynthesis processes
Solar system abudances contain signatures of nuclear structure and nuclear stability. They are the result of different nucleosynthesis processes operating in different astrophysical environments and the chemical evolution of the galaxy.
8 4...6 10 y M~10 Mo
dense 6 molecular star formation (~3%) H condensation clouds 1010 He
8 10 O C Ne interstellar 106-1010 y 6 Si S Fe medium 10 stars star M > 0.08 M D Ca Ni o s 104 infall dudustst 2 winds 10 Ge Sr SN explosion Ba mixing B Xe Pb SNR's & ~90% 100 Li Pt hot Be r s bubbles r s Galactic compact Abundance relative to Silicon = 10 −2 remnant 10 SNIa (WD, 0 20 40 60 80 100 120 140 160 180 200 220 halo 2 6 Mass Number 10 -10 y NS,BH) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Stellar nucleosynthesis processes
In 1957 Burbidge, Burbidge, Fowler and Hoyle and independently Cameron, suggested several nucleosynthesis processes to explain the origin of the elements.
νp-process “neutrino-proton process” s-process 184 rp-process “slow process” via chain of stable nuclei through “rapid proton process” 162 via unstable proton-rich nuclei neutron capture through proton capture Pb (Z=82)
Proton dripline 126 (edge nuclear stability) Number of protons
Sn (Z=50)
r-process “rapid process” via Ni (Z=28) 82 unstable neutron-rich nuclei
Neutron dripline 50 (edge nuclear stability) 28 Fusion up to iron 20 Big Bang Nucleosynthesis 2 8 Number of neutrons Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Nucleosynthesis beyond iron (Traditional description)
Three processes contribute to the nucleosynthesis beyond iron: s-process, r-process and p-process (γ-process).
10 2
80 1 10 s r s ] 0 70 p-drip 6 10 r 10 -1 60 -2 Z 10 50 10 -3 115 Sn 180 p n-drip -4 138 W 40 10 La Abundances [Si=10 152 10 -5 Gd 30 164 180 m Ta 10 -6 Er 40 60 80 100 120 80 100 120 140 160 180 200 N A
10−12 −3 s-process: relatively low neutron densities, nn = 10 cm , τn > τβ 20 −3 r-process: large neutron densities, nn > 10 cm , τn < τβ. p-process: photodissociation of s-process material. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Heavy elements and metal-poor stars Cowan & Sneden, Nature 440, 1151 (2006) Stars rich in heavy r-process elements (Z > 50) 0 and poor in iron (r-II stars, [Eu/Fe] > 1.0).
ε Robust abundance patter for Z > , −2 50 consistent with solar r-process abundance. −4 These abundances seem the result of events Relative log that do not produce iron. [Qian & Wasserburg, −6 Phys. Rept. 442, 237 (2007)]
−8 30 40 50 60 70 80 90 Possible Astrophysical Scenario: Neutron star Atomic Number mergers. 0.5 (b) Sr 0 Zr translated pattern of CS 22892-052 (Sneden et al. 2003) Ru Stars poor in heavy r-process elements but -0.5 Mo Pd -1 with large abundances of light r-process ) Y Z ( elements (Sr, Y, Zr) ε -1.5 Nb log -2 Production of light and heavy r-process Ag elements is decoupled. -2.5 -3 HD 122563 (Honda et al. 2006) Eu
Astrophysical scenario: neutrino-driven -3.5 40 50 60 70 80 winds from core-collapse supernova Atomic Number (Z) Honda et al, ApJ 643, 1180 (2006) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary r-process astrophysical sites
Core-collapse supernova Neutron star mergers
Neutrino-winds from protoneutron Matter ejected (∼ 0.01 M ) stars. dynamically during merger. Aspherical explosions, Jets, Electromagnetic emission from Magnetorotational Supernova, ... radioactive decay of r-process nuclei [Winteler et al, ApJ 750, L22 (2012); [KiloNova, Metzger et al (2010), Mösta et al, arXiv:1403.1230 ] Roberts et al (2011), Bauswein et al (2013)] What is the additional contribution from the accretion disk? Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Collapse and Explosion
ν Progenitor (~ 15 M ) M M ν (Lifetime: 1 ~ 2 107 y) ν ν− Sphere M M H O/Si Hot 13 Fe ν Extended Mantle ~10 cm Dense He 7 10 cm Core ν ν Early ν ν "Protoneutron" ~0.1−1 Sec. Star M 6 Dense 10 cm Core ν ν ν Late Protoneutron Star ν (R ~ 20 km) Shock
Supernova ν 3 10 8 cm e ~1 Sec. Collapse of e + p n + νe and Core (~1.5 M ) Photodisintegration of Fe Nuclei "White Dwarf" (R ~ 100 km) ν e (Fe−Core) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Role of weak interactions
Main processes: − νe + n p + e + ν¯e + p n + e
Neutrino interactions determine the proton to neutron ratio.
Neutron-rich ejecta: Neutrino cooling and Neutrino-driven wind 105 Lν¯e h i hEν¯ i − hEν i > 4∆np − − 1 hEν¯ i − 2∆np e e Lνe e ν , ν 104 e,µ,τ e,µ,τ m in k
R Ni neutron-rich ejecta: r-process 103 Si
proton-rich ejecta: νp-process He 102 νp-process ν , –ν r-process O e,µ,τ e,µ,τ R We need accurate knowledge of νe and ns ~10
Rν ν¯e spectra PNS 1.4 α, p α, p, nuclei 3 M(r) in M n, p α, n α, n, nuclei Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Weak rates in the decoupling region Several process contribute to the determination of neutrino spectra.
νen νen ν¯ n ν¯ n νµ/τ n νµ/τ n → e → e → ν p ν p e e ν¯e p ν¯e p ν p ν p → → µ/τ → µ/τ + νen e−p ν¯e p e n + → → νµ/τ ν¯µ/τ e−e + + → νeν¯e e−e ν ν¯ e e → e e − → νµ/τ ν¯µ/τ NN NN νeν¯e NN NN ν ν¯ NN NN → → e e → ν e ν e νee± νee± ν¯ e± ν¯ e± µ/τ ± µ/τ ± → e → e → 3 3 3 10 10νe 10ν¯e νµ/τ
102 102 102
101 101 101 ] 0 0 0 −1 10 10 10
[km −1 −1 −1
λ 10 10 10 1/ 10−2 10−2 10−2
10−3 10−3 10−3
10−4 10−4 10−4
14 13 12 11 14 13 12 11 14 13 12 11 Baryon Density, log (ρ [g cm−3]) Baryon Density, log (ρ [g cm−3]) Baryon Density, log (ρ [g cm−3]) 10 10 10
− νe: dominated by charged-current process: νe + n p + e
ν¯e: interplay between charged-current and neutral current processes. + e + n → p + ν¯e dominates the production. − 0 − 0 ν¯e + e → ν¯e + e and ν¯e + n → ν¯e + n fundamental for spectra formation and decoupling. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Neutrino interactions at high densities Most of Equations of State treat neutrons and protons as “non-interacting” (quasi)particles that move in a mean-field potential Un,p(ρ, T, Ye). 2 pn ∗ En = ∗ + mn + Un 2mn µ µ n e
2 pp ∗ Ep = ∗ + mp + Up 2mp
∗ ∗ Q = mn − mp + Un − Up
µ p
νe absorption opacity affected by final state electron blocking ∗ ! Eν + ∆m + ∆U − µe χ(E ) ∝ (E + ∆m∗ + ∆U)2 exp , ∆U = U − U ν ν kT n p
ν¯e absorption affected by energy threshold (∆U). ∗ 2 ∗ χ(Eν) ∝ (Eν − ∆m − ∆U) Eν > ∆m + ∆U larger symmetry energy (larger ∆U) implies: i) the larger the energy difference between νe and ν¯e; ii) smaller electron flavor luminosities. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Constrains in the symmetry energy
Combination nuclear physics experiments and astronomical observations (Lattimer & Lim 2013) Isobaric Analog States (Danielewicz & Lee 2013)
40 100 Danielewicz & Lee 2013 IAS DD2 Danielewicz & Lee 2013 IAS+Skins 90 35 Lattimer & Lim 2013 NL3 DD2 80 TM1 30 NL3 TMA TM1 70 SFHo 25 TMA SFHo 60 SFHx SFHx
[MeV] FSUgold 20 FSUgold 50 IUFSU IUFSU U [MeV] sym 15 LS180 40 E LS220 30 10 20 5 10 0 -2 -1 0 -3 -2 -1 10 2 5 10 2 10 2 5 10 2 5 10 2 5 -3 -3 nB [fm ] nB [fm ]
Figures from Matthias Hempel (Basel) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary
Impact on neutrino luminosities and Ye evolution
1D Boltzmann transport radiation simulations (artificially induced explosion) for a 11.2 M progenitor based on the DD2 EoS (Stefan Typel and Matthias Hempel).
1052 0.60 0.58 0.56 51 0.54 10 0.52 0.50 0.48 50 Electron fraction 0.46 Luminosity [ergs/s] 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [s] Time [s] 13 100 12 νe 90 11 80 ν¯e /baryon] 70
10 B [MeV]
k 60 i 9 νx
ν 50
E 8 40 h 7 30 6 20 0 2 4 6 8 10 Entropy [ 0 2 4 6 8 10 Time [s] Time [s]
Ye is moderately neutron-rich at early times and later becomes proton-rich. GMP, Fischer, Huther, J. Phys. G 41, 044008 (2014). Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Nucleosynthesis
107 6 10 11.2 105 104 103 102 101 100 1 10− 2 Rel. abundance 10− 3 10− 4 10− 50 60 70 80 90 100 110 Mass number A 2 10− 3 10− HD 122563 4 10− 5 10− 6 10− 7 10− 8 10−
Elemental abundance 9 10− 25 30 35 40 45 50 55 Charge number Z
Elements between Zn and Mo, including 92Mo, are produced Mainly neutron-deficient isotopes are produced No elements heavier than Mo (Z = 42) are produced. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Neutron decay
The neutron-proton energy difference in the medium could be of the order of several 10s MeV. Neutron decay is an important source of low energy neutrinos. − n p + e + ν¯e + e + n p + ν¯e This is part of the direct URCA process in neutron stars [Lattimer et al, (1991)] 9 νe 10 8
7 〉 [MeV] 1 ν 〈 E L 6 1 - no neutron decay channel km
H including neutron−decay channel 5 0.1 12 0.5 1 2 3 5 10 ¯νe 11
Opacity Ν + - + ® 0.01 e e p n 10 + Νe + p ® n + e 9 〉 [MeV]
8 ν 0.001 〈 E 0 10 20 30 40 7 6 Energy HMeVL 0.5 1 2 3 5 10 20 Fischer, Lohs, GMP, Qian, in preparation t − t [s] bounce Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Neutron star mergers: Short gamma-ray bursts and r-process
Mergers are expected to eject around 0.01 M of very neutron rich-material (Ye ∼ 0.01). A similar amount of less neutron-rich material (Ye ∼ 0.1–0.2) is expected from the accretion disk. They are also promising sources of gravitational waves. Observational signatures of the r-process? Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Neutron-star mergers: Astrophysically robust
Korobkin, Rosswog, Arcones, & Winteler, MNRAS 426, 1940 (2012)
0.5 Yi Ye -4 0.4 10 0.2
-5 0.3 10 0.1
10-6 0.2 0 13 14 10 10 ns1.0-ns1.0 ns1.4-ns1.4 ejecta mass fraction 3 -7 0.1 l [g/cm ] 10 ns1.2-ns1.2 ns1.2-ns1.0 ns1.4-ns1.0 -8 ns1.4-bh5 0 10 ns1.4-bh10 0 0.05 0.1 0.15 0.2 0.25 0.3 120 130 140 150 160 170 180 190 200 210 Ye Mass number A Robust to variations of the equation of state
Bauswein, Goriely, Janka, ApJ 773, 78 (2013) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Making Gold in Nature: r-process nucleosynthesis
250 Known mass Known half−life r−process waiting point (ETFSI−Q)
100 200 98 96
94
92
90
88 Solar r abundances 86 84 188 190 186 82
80
78 184 180 182 76 178 176 74 164 166 168 170 172 174 150 72 162 70 160 N=184 68 158
66 156 154 64 152 150 62 140 142 144 146 148 1 60 138 134 136 58 130 132 0 128 10 56 54 126 124 10 −1 52 122 The r-process requires the knowledge of 120 50 116 118 10 −2 48 112 114 110 46 −3 108 10 100 106 N=126 44 104 the properties of extremely 100 102 42 10 98 96 40 92 94
38 88 90 86 84 r−process path 36 82 neutron-rich nuclei: 34 80 78 32 74 76
30 72 70 28 66 68 64 26 62 N=82 28 60 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 Nuclear masses. Beta-decay half-lives. Neutron capture rates. Fission rates and yields. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary General features r-process
120
100 r-process abundance
200
80 180 ) 1 Z 10 160 A) 40 N 0 1 r , 10 60 (Si = 10 120 Mass number ( –1 log(T s–1) 10 100 6 ) 1.0 –2 80 Proton number ( number Proton 40 10 0.5 0.0 –0.5 –1.0 20 –1.5 –2.0 –2.5
0 0 20 40 60 80 100 120 140 160 Neutron number (N)
Figure from Peter Möller. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Global mass models vs experiment
Similar behaviour for all mass models. Problems in reproducing masses in transitional regions. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary General features evolution in mergers
12 )
-3 10 FRDM MASS MODEL r-process stars once electron fermi energy 8 ∼ 6 drops below 10 MeV to allow for ( ρ ) (g cm 4
− 10 beta-decays (ρ ∼ 1011 g cm 3). 2 Log 0 Important role of nuclear energy 10 production. K 1 Increases temperature to values that allow 9 T/10 for an (n, γ) (γ, n) equilibrium. 0.1
r-process operates at moderate high )
-1 6 entropies, s ∼ / . s 50–100 k nuc -1 5 4 3 2 Trajectories from simmulation A. Bauswein and 1 dE/dt (Mev nuc H.-T. Janka. 0.1 1 Time (s) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Final abundances different mass models
neutron captures computed consistently for each mass model.
solar r-process abundances Rn/seed 1920 -3 FRDM MASS MODEL 1700 WS3 MASS MODEL 10 1470 711 676 623 10-4
Final abundances 10-5
10-6
HFB21 MASS MODEL DZ31 MASS MODEL 10-3
10-4
Final abundances 10-5
10-6 120 140 160 180 200 220 240 260 120 140 160 180 200 220 240 260 A A
J. Mendoza-Temis, G. Martinez-Pinedo, K. Langanke, A. Bauswein, H.-Th. Janka, arXiv:1409.6135 [astro-ph.HE] Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Temporal evolution (selected phases)
10-3 10-3 = 1 = 1 n/s n/s 10-4 10-4
10-5 10-5
10-6 10-6 Abundances at R Abundances at R 10-7 10-7 β β τ τ 10-3 10-3 = = ) ) γ γ
(n, -4 (n, -4
τ 10 τ 10
10-5 10-5
10-6 10-6
Abundances at 10-7 Abundances at 10-7 solar r-process abundances solar r-process abundances -3 -3 10 Rn/s 10 Rn/s 623 623 -4 676 -4 676 10 711 10 711 1470 1470 10-5 1700 10-5 1700 1920 1920 10-6 10-6
Abundances at 1 Gyr FRDM MASS MODEL Abundances at 1 Gyr DZ31 MASS MODEL 10-7 10-7 100 120 140 160 180 200 220 240 260 280 100 120 140 160 180 200 220 240 260 280 A A Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary The role of N ∼ 130
6 DZ31 5 WS3 HFB 21 FRDM 4
3 (MeV) n S 2
1 Yb (Z=70) Isotopes 0 120 125 130 135 140 Neutron Number
Both FRDM and HFB models predict a sudden drop in neutron separation energies approaching N ∼ 130 for Z ∼ 70. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Delayed outflows Black-Hole accretion disks
t ~day ? t ~week luminosity time Disk Outflow OR Ye ~ 0.2 - 0.4
Dynamical Ejecta HMNS Disk Ye < 0.1
Figure from Metzger & Fernández, arXiv:1402.4803 [astro-ph.HE] Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Delayed outflows Black-Hole accretion disks
R. Fernández and B. D. Metzger, MNRAS 435, 502 (2013)
-3 density [g cm ] Ye entropy [kB / baryon] 1 102 104 106 0.1 0.15 0.2 10 30 100 300
4
2 cm] 7 0 [10 z
-2
-4 0 2 4 6 8 2 4 6 8 2 4 6 8 x [107 cm] x [107 cm] x [107 cm] 6
4
2 cm] 8 0 [10 z -2
-4
-6 0 2 4 6 8 10 12 2 4 6 8 10 12 2 4 6 8 10 12 x [108 cm] x [108 cm] x [108 cm]
Long-lived hypermassive neutron star explored in: Metzger & Fernández, arXiv:1402.4803 [astro-ph.HE] Perego et al., arXiv:1405.6730 [astro-ph.HE] Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Nucleosynthesis in accretion disks outflows
s_def s_m0.01 s_M10 s_s10 s_v0.01 s_y0.05 s_def_neutrinos s_m0.10 s_r75 s_s6 s_v0.10 s_y0.15 10-2
10-3
10-4
10-5
10-6
10-7
10-8 Abundance
10-9
10-10
10-11
10-12 100 120 140 160 180 200 220 240 Mass number A
Fernández, Huther, Arcones, GMP, Metzger, in preparation. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Radioactive heating and light curve Metzger, GMP, Darbha, Quataert, Arcones et al, MNRAS 406, 2650 (2010) 1042 The r-process heating at late times
−1.3 ) goes like t . Similar to nuclear −1 waste decay in terrestrial reactors. 1041 Independent of the ejecta
Luminosity (erg s Efficiency = 1.0 composition. Efficiency = 0.5
1040 Independent of the nuclear mass 0.1 1 10 Time (days) Time since GRB 130603B (d) model. 1 10 10–11 21 X-ray F606W Typical luminosities 1000 times 22 F160W
23 those of a Nova. Important –12 10 X-ray Dux (erg s contribution to photon opacities 24
25
from Lanthanides (Kasen et al, –1 –13 10 cm AB magnitude 26 –2 2013). ) 27
28 Probably observed in 10–14 29
GRB 130603B. 104 105 106 Time since GRB 130603B (s) Tanvir et al, Nature 500, 457 (2013) Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary What about the actinides?
solar r-process abundances -3 FRDM 10 WS3 HFB21 DZ10 10-4 DZ31
10-5
-6
Abundances at 1 week 10 Rn/s = 623
10-7 120 140 160 180 200 220 240
Actinides can be an important opacity source at timescales of weeks. Introduction Nucleosynthesis in supernova neutrino-driven winds Nucleosynthesis in compact-object mergers Summary Summary
Neutrino-winds simulations based on an EoS that is consistent with constrains on the symmetry energy produce elements between Zn and Mo, including 92Mo. No heavier elements are produced. The major opacity uncertainties relevant to nucleosynthesis are related to the interaction of ν¯e with matter. Neutron star mergers produce a robust r-process abundance pattern. Radioactive decay of r-process ejecta produces an electromagnetic transient. Observed in GRB 130603B The combination of dynamical and disk outflow ejecta can account for the whole of solar system r-process abundances.