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Nucleosynthesis of Heavy Elements in Supernovae and Neutron-Star Mergers

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Nucleosynthesis of Heavy Elements in Supernovae and Neutron-Star Mergers Nucleosynthesis of heavy elements in supernovae and neutron-star mergers Almudena Arcones Solar system abundances Solar photosphere and meteorites: chemical signature of gas cloud where the Sun formed Contribution of all nucleosynthesis processes Big Bang: H, He Lodders 2003 iron peak in stellar interiors r-process s-process burning s-process: slow neutron capture r-process: neutron capture rapid neutron capture abundance = mass fraction / mass number r-process path uranium Sneden & Cowan 2003 masses measured at the ESR 82 r-process path 126 gold stable nuclei 50 will be measured 82 with CR at FAIR silver 28 nuclides with 20 50 known masses Z 1st peak: A≈80 → N=50 2nd peak: A≈130 → N=82 8 28 20 3rd peak: A≈195 → N=126 iron 8 N rare earth peak A≈165 → ? r-process path uranium masses measured neutron capture faster than beta decayat the ESR → high neutron density 82 seed nuclei + neutrons Yn/Yseed > 100 r-process path 126 gold stable nuclei 50 r-processwill be measured 82 with CR at FAIR silver 28 nuclides with 50 Z 20 known masses 8 28 20 8 N iron Galactic chemical evolution First stars: H, He Heavy elements New generation of stars Interstellar medium (ISM) The very metal-deficient star HE 0107-5240 (Hamburg-ESO survey) The very metal-deficient star Oldest observed stars HE 0107-5240 Silver Eu Gold Elemental abundances in: - ultra metal-poor stars and - solar system ‣Robust r-process for 56<Z<83 ‣Scatter for lighter heavy elements, Z~40 How many “r-processes” contribute to solar system and UMP stars abundances? Sneden, Cowan, Gallino 2008 Where does the r-process occur? Core-collapse supernovae Neutron star mergers Neutron stars Cas A (Chandra X-Ray observatory) Neutron-star merger simulation (S. Rosswog) •neutrino-driven winds (Woosley et al. 1994,…) •dynamic ejecta •jets (Winteler et al. 2012) •neutrino-driven winds •evaporation disk •shocked surface layers (Ning, Qian, Meyer 2007) •neutrino-induced in He shell (Banerjee, Haxton, Qian 2011) (Lattimer & Schramm 1974, Freiburghaus et al. 1999, ....) Core-collapse supernovae the death of massive stars and the birth of new elements EoS Core-collapse supernova simulations Hot bubble Shock Proto-neutron star Long-time hydrodynamical simulations: - ejecta evolution from ~5ms after bounce to ~3s in 2D (Arcones & Janka 2011) and ~10s in 1D (Arcones et al. 2007) - explosion triggered by neutrinos - detailed study of nucleosynthesis-relevant conditions Core-collapse supernova simulations slow ejecta reverse shock shock neutrino-driven wind Long-time hydrodynamical simulations: - ejecta evolution from ~5ms after bounce to ~3s in 2D (Arcones & Janka 2011) and ~10s in 1D (Arcones et al. 2007) - explosion triggered by neutrinos - detailed study of nucleosynthesis-relevant conditions R [km] Initial Phase of Collapse R [km] Neutrino Trapping (t ~ 0) δ (t ~ 0.1s, c ~10¹² g/cm³) R Fe ~ 3000 RFe νe νe νe ~ 100 Si Si ν e Fe, Ni Fe, Ni νe νe M(r) [M ] M(r) [M ] 0.5 1.0 ~ MCh 0.5 Mhc 1.0 heavy nuclei Si−burning shell Si−burning shell R [km] R [km] Shock Propagation and ν e Burst δ Bounce and Shock Formationδ (t ~ 0.11s, c ∼< 2 o) R (t ~ 0.12s) RFe Fe Rs ~ 100 km νe radius of νe shock Rν formation νe position of νe shock ~ 10 Si ν Si e formation ν Fe e Fe, Ni free n, νe p Ni νe M(r) [M ] 0.5 1.0 M(r) [M ] 0.5 1.0 nuclear matter δ nuclearδ matter nuclei nuclei ( ∼> ο) Si−burning shell Neutrino-driven windsSi−burning shell Shock Stagnation and ν Heating, R [km] R [km] Neutrino Cooling and Neutrino− Explosion (t ~ 0.2s) 5 10 Driven Wind (t ~ 10s) neutrons and protons form α-particles Rs ~ 200 α-particles recombine into seed nuclei 4 ν ,ν νe,µ,τ ,νe,µ,τ 10 e,µ,τ e,µ,τ Ni R ~ 100 3 g free n, p Si 10 Si p R ν ~ 50 2 α He νe 10 n νe,µ,τ ,νe,µ,τ r−process? νe,µ,τ ,νe,µ,τ νe O R ns ~ 10 Rν M(r) [M ] n M(r) [M ] PNS 1.3 gain layer 1.5 PNS 1.4 α,n 9 3 n, p α,n, Be, cooling layer 12 C, seed NSE → charged particle reactions / α-process → r-process Figure 2. Schematic representation of the processes that occur in a c o l l a p s i n g s t e l l a r i r o n c o r e o n t h e w a y t o th e weak r-process supernova explosion. The diagrams (from top left to bottom rightT) v i s=u a l10ize -th 8e pGKhys i c a l c o n d i t i o n s a t t h e o n s e t8o -f 2 GK νp-process core collapse, neutrino trapping, shock formation, propagation of the prompt shock, shock stagnation and revival by neutrino heating, and r-process nucleosynthesis in the neutrino-driven wind of the newly formed neutron star, T < 3 GK respectively, as suggested by current computer simulations. In theforup ap reviewer par seets o Arconesf the fi &g uThielemannres the d y(2013)namical state is shown, with arrows indicating the flow of the stellar fluid. The lower parts of the figures contain information about the nuclear composition of the stellar plasma and the role of neutrinos during the different phases. 41 Which elements are produced in neutrino winds? Arcones et al 2007 Silver no r-process ❒ mass element Radius [cm] Shock Reverse shock Neutron star time [s] Lighter heavy elements in neutrino-driven winds νp-process weak r-process proton rich neutron rich observations Honda et al. 2006 Observation pattern reproduced! Overproduction at A=90, magic neutron number N=50 (Hoffman et al. 1996) suggests: Production of p-nuclei only a fraction of neutron-rich ejecta (Wanajo et al. 2011) Arcones & Montes (2011) C.J. Hansen, Montes, Arcones (2014) Lighter heavy elements in neutrino-driven winds νp-process weak r-process proton rich neutron rich observations Sr Sr 5 Overproduction at A=90, magic neutron1 0Observation.66 pattern reproduced! − 0.49 − 0.65 6 − 0number.48 N=50 (Hoffman et al. 1996) suggests:2 0.64 7 − 0Production.63 of p-nuclei − 0only.47 a fraction of neutron-rich ejecta 0.62 8 3 − (Wanajo et al. 2011) − 0.61 9 0.46 0.60 − 4 10 0.45 − Ye 0.59 Ye 0.58 (Arcones &− Montes, 2011) 11 0.44 5 0.57 − − 0.56 12 0.43 6 0.55 − − 0.54 13 0.42 − 7 0.53 14 0.41 − 0.52 − 0.51 15 0.40 8 40 50 60 70 80 90 100 110 − 40 50 60 70 80 90 100 110 − Entropy [kB/nuc] Entropy [kB/nuc] Arcones & Bliss (2014) Key reactions: weak r-process 2 10− (α,n) baseline Ye =0.45 3 10− λ 10 for Z =10 30 (α,n) · − 4 λ(α,n) 0.1forZ =10 30 10− · − 5 10− 6 10− abundance 7 10− 8 10− 9 10− baseline Ye =0.45 3 10− λ 10 for Z =30 40 (α,n) · − 4 λ(α,n) 0.1forZ =30 40 10− · − 5 10− 6 10− abundance 7 10− 8 10− 9 10− 10 15 20 25 30 35 40 45 50 55 Bliss, Arcones, Montes, Pereira (in prep.) Z Origin of elements from Sr to Ag Astrophysical site Observations ν wind Chemical evolution [Sr/Fe] Nucleosynthesis: Hansen et al. 2013 identify key reactions [Fe/H] Neutron star mergers Neutron star mergers Ejecta from three regions: • dynamical ejecta • neutrino-driven wind • disk evaporation disk evaporation Rosswog 2013 Neutron star mergers: robust r-process 1.2M 1.4M 1.4M 1.4M 2M 1.4M − − − Right conditions for a successful r-process (Lattimer & Schramm 1974, Freiburghaus et al. 1999) nucleosynthesis of dynamical ejecta robust r-process: - extreme neutron-rich conditions (Ye =0.04) - several fission cycles Korobkin, Rosswog, Arcones, Winteler (2012) see also Bauswein, Goriely, and Janka Hotokezaka, Kiuchi, Kyutoku, Sekiguchi, Shibata, Tanaka, Wanajo Ramirez-Ruiz, Roberts, ... T (GK) ρ (g cm-3) robust r-process Korobkin et al. 2012 Radioactive decay in neutron star mergers Transient with kilo-nova luminosity (Metzger et al. 2010, Roberts et al. 2011, Goriely et al. 2011): direct observation of r-process, EM counter part to GW (see also Kulkarni 2005: macronova) Multi messenger (e.g. Metzger & Berger 2012, Rosswog 2012, 2013, Bauswein et al. 2013) Berger, Fong & Chornock, 2013 Tanaka & Hotokezaka, 2013, Hotokezaka et al. 2013 Grossman, Korobkin, Rosswog, Piran, 2014 Neutron star mergers: neutrino-driven wind 3D simulations after merger Perego et al. (2014) disk and neutrino-wind evolution neutrino emission and absorption Nucleosynthesis: 17 000 tracers 4 3 2 1 Martin et al. (2015) see also Fernandez & Metzger 2013, Metzger & Fernandez 2014, Just et al. 2014, Sekiguchi et al. Neutron star mergers: neutrino-driven wind Martin et al. (2015) Time and angle dependency Black hole formation determines time for wind nucleosynthesis (Fernandez & Metzger 2013, Kasen et al. 2015) Early times: low Ye: heavy elements Late times: Ye ~0.35: lighter heavy elements angle dependency Martin et al. (2015) Wind and dynamic ejecta Wind ejecta complement dynamic ejecta Complete mixing: solar system abundances and UMP stars Partial mixing: Honda-like star? dynamical ejecta disk ejecta Martin et al. (2015) Neutron star mergers and GCE Argast, Samland, Matteucci, Romano, Thielemann, Qian (2004) Arcones, Korobkin, Rosswog (2014) -6 M(Eu) = 9x10 M⊙ -6 3x10 M⊙ -6 1x10 M⊙ time delay = 1 10 100 Myr +209.1 -1 merger contribution always [Fe/H]>-2 merger rate = 83 -66.1 Myr (Kalogera et al.
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