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Nuclear Astrophysics: the Origin of Heavy Elements Lecture 3: the R Process

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Nuclear Astrophysics: The origin of heavy elements Lecture 3: The r process Gabriel Martínez Pinedo Isolde lectures on nuclear astrophysics May 9–11, 2017 Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Outline 1 Signatures of heavy element nucleosynthesis 2 Nucleosynthesis in core-collapse supernovae 3 Nucleosynthesis in neutron star mergers Dynamical ejecta Accretion disk ejecta 4 Summary Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Nucleosynthesis beyond iron 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: low neutron densities, nn = 10 cm , τn > τβ (site: intermediate mass stars) 20 −3 r process: large neutron densities, nn > 10 cm , τn τβ (unknown astrophysical site) p process: photodissociation of s-process material. Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Time evolution: metalicity [Fe/H] ~ -5 [Fe/H] ~ -3 Astronomers use the metalicity: ! ! NFe NFe [Fe=H] = log10 − log10 NH ∗ NH as a proxy for age. Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Evolution metalicity Sneden, Cowan & Gallino 2008 a 1.5 1.0 Core-collapse Supernovae Type Ia 0.5 [Mg/Fe] 0 – 0.5 b 1.5 1.0 0.5 [Eu/Fe] 0 – 0.5 –3 –2 –1 0 [Fe/H] r process occurs already at early galactic history Large scatter at low metalicities: r process is related to rare events not correlated with iron. Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star 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 > 50, −2 consistent with solar r-process abundance. −4 Abundances are the result of events that do Relative log not produce iron. [Qian & Wasserburg, Phys. −6 Rept. 442, 237 (2007)] −8 30 40 50 60 70 80 90 Atomic Number 0.5 (b) Sr 0 Zr translated pattern of CS 22892-052 (Sneden et al. 2003) Ru -0.5 Mo Pd -1 Stars poor in heavy r-process elements but ) Y Z ( ε -1.5 with large abundances of light r-process Nb log -2 elements (Sr, Y, Zr) Ag -2.5 Production of light and heavy r-process -3 HD 122563 (Honda et al. 2006) Eu elements is decoupled. -3.5 40 50 60 70 80 Atomic Number (Z) Honda et al, ApJ 643, 1180 (2006) Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary r-process astrophysical sites Core-collapse supernovae Neutron star mergers Explosion of massive stars Mergers eject around 0:01 M of very (M & 9 M ) neutron rich-material (Ye ∼ 0:01). Similar amount of less neutron-rich matter Site: neutrino-winds from cooling (Y 0:2) ejected from accretion disk. of hot protoneutron star. e & Low frequency, high yield High frequency (∼ 0:3 yr−1), low −4 −5 yield ejecta (10 –10 M ) Observational signature: electromagnetic transient from radioactive decay of Observations: not every r-process nuclei [Kilonova/Macronova, supernovae produces r process Metzger et al (2010)] Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Measurements long-lived radioactive nuclei Both the 244Pu (τ = 81 Myr) accreted via interstellar particles in the Earth deepsea floor and the Early Solar System abundanced are naturally explained with the low-rate/high-yield astrophysical scenario. [Hotokezaka et al, Nature Physics 11, 1042 (2015)] CC Supernova 10,000 LIGO/Virgo R-element mass ( Macronova 1,000 candidate ) 1 A − Pu ≥ r 90) 100 My ( 0 R 10 Compact binary merger 1 Advanced LIGO/ Virgo/KAGRA 0.1 0.0001 0.001 0.01 0.1 1 Mej (Msun) Any astrophysical site should fulfill: RMej = M(A > 90) Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Core-collapse supernovae H.-Th. Janka, et al, PTEP 01A309 (2012) " ! The movie of the supernova simulation is available here Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Neutrino-driven winds Main processes: − νe + n p + e + ν¯e + p n + e Neutrino interactions determine the proton to neutron ratio. Neutrino cooling and Neutrino-driven wind Condition neutron-rich ejecta: 105 Lν¯e h i hEν¯ i − hEν i > 4∆np − − 1 hEν¯ i − 2∆np e e Lν e ν , ν e 104 e,µ,τ e,µ,τ m in k R Ni neutron-rich ejecta: r-process 103 Si ฀ He proton-rich ejecta: νp-process 102 νp-process ν , –ν r-process O e,µ,τ e,µ,τ R Nucleosynthesis sensitive to spectral ns ~10 Rν PNS differences between ν and ν¯ 1.4 α, p α, p, nuclei 3 e e M(r) in M n, p α, n α, n, nuclei Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Evolution luminosities and Ye 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). Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star 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 (A ∼ 90) are produced Mainly neutron-deficient isotopes are produced Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Compact binary systems: gravitational waves Orbital decay Hulse & Taylor binary pulsar Gravitational waves binary black holes merger First detection! 9:50:45 UTC, 14 September 2015 LIGO Hanford signal LIGO Livingston signal Abbott et al, PRL 116, 061102 (2016) Weisberg & Huang, ApJ 829, 55 (2016) Compact binary systems exist and eventually merge Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Merger channels and ejection mechanism In mergers we deal with a variety of initial configurations (netron-star neutron-star vs neutron-star black-hole) with additional variations in the mass-ratio. The evolution after the merger also allows for further variations. NSNS wind; t~100 ms torus unbinding; dyn. ejecta; t~ 1 ms t ~ 1s ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ BH formation ⇒ sGRB ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ NSBH Rosswog, et al, arXiv:1611.09822 Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star 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. Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis 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) Signatures of heavy element nucleosynthesis Nucleosynthesis in core-collapse supernovae Nucleosynthesis in neutron star mergers Summary Final abundances different mass models Mendoza-Temis, Wu, Langanke, GMP, Bauswein, Janka, PRC 92, 055805 (2015) 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 Robustness astrophysical conditions, strong sensitivity to nuclear physics Second peak (A ∼ 130) sensitive to fission yields.
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  • Recent Developments in Radioactive Charged-Particle Emissions

    Recent Developments in Radioactive Charged-Particle Emissions

    Recent developments in radioactive charged-particle emissions and related phenomena Chong Qi, Roberto Liotta, Ramon Wyss Department of Physics, Royal Institute of Technology (KTH), SE-10691 Stockholm, Sweden October 19, 2018 Abstract The advent and intensive use of new detector technologies as well as radioactive ion beam facilities have opened up possibilities to investigate alpha, proton and cluster decays of highly unstable nuclei. This article provides a review of the current status of our understanding of clustering and the corresponding radioactive particle decay process in atomic nuclei. We put alpha decay in the context of charged-particle emissions which also include one- and two-proton emissions as well as heavy cluster decay. The experimental as well as the theoretical advances achieved recently in these fields are presented. Emphasis is given to the recent discoveries of charged-particle decays from proton-rich nuclei around the proton drip line. Those decay measurements have shown to provide an important probe for studying the structure of the nuclei involved. Developments on the theoretical side in nuclear many-body theories and supercomputing facilities have also made substantial progress, enabling one to study the nuclear clusterization and decays within a microscopic and consistent framework. We report on properties induced by the nuclear interaction acting in the nuclear medium, like the pairing interaction, which have been uncovered by studying the microscopic structure of clusters. The competition between cluster formations as compared to the corresponding alpha-particle formation are included. In the review we also describe the search for super-heavy nuclei connected by chains of alpha and other radioactive particle decays.