Nucleosynthesis in Supernovae and the Big-Bang I

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1 IV International Summer School 2005 Center for Nuclear Study, University of Tokyo August 18 23, 2005 Nucleosynthesis in Supernovae and the Big-Bang I Taka Kajino National Astronomical Observatory Department of Astronomy, University of Tokyo 1

2 Solar System Abundance BIG-BANG STARS Constrains Cosmology! Supernova, prompt or delayed? Neutron Star Merger? Gamma-Ray Burst? R-process elements, UNKNOWN ORIGIN? R S N=50) AGB STARS COSMIC-RAYS R S N=82) R S N=126) ++ + Actinide 232 Th (14.05Gy) P 238 U (4.47 Gy) Supernova-γ Process? 2

3 Newest CMB Results Spergel et al. 2003, ApJS, 148, 175. WMAP determined all cosmological parameters? t 0 Model dependent! = /- 0.2 Gyr Only 4.4% baryons are known. What is Ω m or Ω Λ? 3

4 OUTLINE Universe is likely flat and accelerating! Ω B + Ω CDM + Ω Λ = 1 Six (eleven) Parameters! Is BARYON, Ω B = 0.04, consistent with Big-Bang Cosmology and Nucleosynthesis? CANDLE of dark side of the Universe!! What is the nature of CDM, Ω CDM = 0.26? Disappearing CDM Model in Brane World Cosmology! Ichiki, Garnavich, Kajino, Mathews & Yahiro, PRD 68 (2003) What is DARK ENERGY, Ω Λ = 0.7? Growing CDM Model in Brane World Cosmology! Umezu, Ichiki, Kajino, Mathews Nakamura & Yahiro,(2005) (astro-ph/ ) COSMIC AGE ( Gy), strongly model-dependent? Supernova R-Process & Origin of 232 Th, 235,238 U! --- model-independent!? 4

5 We detected ν s, then NEUTRON STAR once formed! SN1987A Can core-collapse supernova produce R-PROCESS elements like 232 Th(τ 1/2 =14.05Gy) which is an celestial cosmic clock? 5

6 Subaru Telescope OBSEVES Extremely Metal- Deficient Stars [Fe/H]=0 SOLAR [Fe/H]<-3 Th II HD6268 6

7 Discovery of Most Metal-Deficient Star HE using SUBARU Telescope Frebel, Aoki, Kajino SUBARU/HDS Collaboration NATURE 434 (2005), 871 Sun [Fe/H] = 0.0 An oldest star of the Milky Way? r-process element! HE [Fe/H] =

8 SUBARU Telescope HDS Honda, Aoki, Kajino et al. (SUBARU/HDS Collaboration), 2004, ApJS 152, 113; 2004, ApJ 607, 474 [Ba/Fe] 0 + AGB [Ba/Eu] 0 solar s-ratio solar r-ratio [Fe/H] SN II SN I + II R-process elements from Type II SNe! [Eu/Fe] 0 Lack due to obs. limit. Early Galaxy [Fe/H] = log(n Fe /N H ) - log(n Fe /N H ) Large abundance scatter at [Fe/H]<-2 is an evidence for INDIVIDUAL supernova episode. Only Core-Collapse TYPE II SUPER- NOVAE are the likely astrophysical sites of the R-Process! 8

9 UNIVERSAL SCALING OF R-PROCESS ABUNDANCES C. Sneden et al. ( ) SOLAR Ba Eu METAL-POOR STARS HD CS BD R-Element Abundance Pattern is: METAL-INDEPENDENT! UNIVERSAL! Cosmic Clock 9

10 Modeling Supernova R-Process Supernovae are the most spectacular events since the Big-Bang, yet they are still poorly understood in their dynamics. Details are important. QuickTime and a YUV420 codec decompressor are needed to see this picture. 10

11 Collapse of the Core Prompt core bounce E(iron core) ~ GM 2 /r ~ erg E(neutron star) ~ GM 2 /r ~ erg E(neutron star) - E(iron core) ~ erg 99% is emitted as neutrinos! E(shock) ~ erg 1% is kinetic energy! Usually the shock is absorbed by dissociating the iron core. Neutrino-heated explosion DELAYED SUPERNOVA 11

12 Steps to a Core Collapse Supernova Stars with M ~ M build up an Fe/Ni core. Maximum core size M ch =5 Y e2 M ~ 1.3 M (Electron Capture). Collapse Separates, inner homologous (v r) core = 1.1 M. outer slowly collapsing core = 0.2 M. The central density increases and reaches nuclear matter density, ρ nucl ~ 2x10 14 g cm -3 (Nuclear EOS). 12

13 Gamow-Teller (β-decay) Strength Distribution of 58 Ni Monte Carlo Shell Model Cal.: Honma-Otsuka (2005) Experiment: Rapaport (1983), NP A410, 371. Exp. Shell Model Cal. Previous SM Cal. 13

14 Monte Carlo SHELL MODEL calculation: Honma & Otsuka (2005) Electron-capture in core collapse may be hindered! 14

15 Expected Effect on Core-Collapse Supernovae Pre-Supernova Calculation: Yoshida and Kajino (2005) Preliminary! Y e Electron fraction increases! Lepton core pressure INCREASES! This may help PROMPT EXPLOSION! Fe-Co-Ni CORE region M / M sol 15

16 Steps to a Core Collapse Supernova Stars with M ~ M build up an Fe/Ni core. Maximum core size M ch =5Y e2 M ~ 1.3 M Collapse Separates, inner homologous (v r) core = 1.1 M. outer slowly collapsing core = 0.2 M. (Electron Capture). The central density increases and reaches nuclear matter density, ρ nucl ~ 2x10 14 g cm -3 (Nuclear EOS). An outward moving shock develops due to nuclear saturation. The shock dissociates the outer iron core into free nucleons. Neutrinos scatter off the heated material behind the shock and deposite energy into p, n, and e + e -. A high entropy heated region forms and begins to lift the outer layers of the star (neutrino-driven wind). 16

17 Before Explosion Fe Co Ni 28 Si SN1987A MODEL: Where occurs r-process? After Explosion?? Ejected Fe-Co-Ni are explosively reproduced in Si-burning! 17

18 Core-Collapse and ν-heating Surface of Iron Core Stalled Shock Front Heating Region Gain Radius Cooling Region p n Proto-NEUTRON STAR 18

19 Supernova Simulations First 300 ms: A. Burrows QuickTime and a YUV420 codec decompressor are needed to see this picture. 10 km 300 km 19

20 Neutrino Heated Bubble forms Neutrino Luminosity ~10 53 erg/s Neutrino Heating produces a high entropy bubble. Woosley et al. 1994, ApJ 433, km Proto neutron-star forms. 20

21 General Relativistic Models of ν-driven Winds Otsuki, Tagoshi, Kajino and Wanajo 2000, ApJ 533,

22 Nucleosynthesis + Diffusion Equation for Z < 100 (~3000 species) Given T & ρ : Nuclear Reactions β-decays Thermonuclear Reaction Rate Diffusion Boltzmann average Cross Section 22

23 Neutrino-Driven Wind Model: 1D-Hydro. Steady-Flow Heavy nuclei cannot exist! T 9 = T / 10 9 n+p + 4 He Seeds (70<A<120) are created! n + 4 He + seeds n-capture flow creates r-elements (80<A<250). n + seeds + r-elements r-process freezeout τ dyn time (sec) 23

24 n, p 4 He Nucleosynthesis in SN ν - Driven Wind d t No heavy nuclei! NSE α-process r-process freezeout 24

25 SUPERNOVA R-PROCESS t = 0 Pb Otsuki, Tagoshi, Kajino & Wanajo 2000, ApJ 533, 424 Wanajo, Kajino, Mathews & Otsuki 2001, ApJ 554, 578 Z Fe t = 0 Neutrino-driven wind forms right after SN core collapse. n + p + α Fe56 Pb208 N t = 18 ms Seeds form. Exotic neutron-rich 78 Ni Ni78 Pb t = 568 ms 1 s Heavy r-elements synthesize. Fe 25

26 UNIVERSAL SCALING OF R-PROCESS ABUNDANCES C. Sneden et al. ( ) SOLAR Ba Eu METAL-POOR STARS HD CS BD R-Element Abundance Pattern is: METAL-INDEPENDENT! UNIVERSAL! Cosmic Clock 26

27 Universal Abundances C. Sneden et al. ( ) Universality applies only for 56 < Z < 75! Z < 56 : Large Dispersion Two r-processes? Different Conditions at early times? Another process???? UNIVERSALITY! age indicater Z > 75 uncertain? Nuclear Physics? BH vs. NS formation? 27

28 R-Process Yields in Type-II SN ν-driven Wind Model Sasaqui, Kajino, Mathews, Otsuki, & Nakamura 2005, ApJ, in press. Solar System R-abundance Our model calculation Universality holds! 2 rd peak r-elements 3 rd peak r-elements actinoids 28

29 Nuclear Physics Origin of Universality Chart r-process path 3-rd peak 2-nd peak No (sub-)shell closure! No structureuniversality 29

30 Dependence upon Nuclear Input Otsuki, Mathews & Kajino 2003, NewA 8, 767 Different beta-decay rates Different Mass Formulae Abundance pattern is most sensitive to the beta-decay rate. 30

31 PRIMARY PROCESSES Big-Bang Nucleosynthesis Solar ν - Problem Supernova R-Process Initially p& n NSE α-process R-process (neutron-rich) 31

32 Reaction Sensitivity Power Index Sensitivity Parameter 32

33 R-Process Sensitivity to Individual Reaction Factor of 2 change of α(αn,γ) 9 Be reaction rate About factor 50 change in r-element yields! (slowly expanding ν-wind model) α(αn,γ) 9 Be ~ 50 α(αn,γ) 9 Be x 2 33

34 Relevant Reactions in R-Process & SENSITIVITY Sasaqui, Kajino, Mathews, Otsuki & Nakamura, ApJ (2005) submitted. 34

35 Identified Important Reaction Flow Paths Woosley & Hoffman (1992) (3) (1) Sasaqui, Kajino, Mathews, Otsuki & Nakamura ApJ (2005), in press. (2) Terasawa, Sumiyoshi, Kajino, Mathews & Tanihata ApJ 562 (2001)

36 EXPERIMENT Utsunomiya et al. PRC63 (2001), (1) α(αn,γ) 9 Be(α,n) 12 C 35%(1σ) Sumiyoshi, Utsunomiya, Goko, and Kajino, Nucl. Phys. A709 (2002), 467 Woosley & Hofmann ApJ 395 (1992)

37 Radiative-Capture Reaction Photo-Disintegration Reaction 37

38 (2)α(t,γ) 7 Li 30%(1σ) REMOVING UNCERTAINTY! R-PROCESS & BIG-BANG REACTION E cm (MeV) STRUCTURE 38

39 (3) 7 Li(n,γ)8Li(α,n) 11 B Factor 2 (1σ) H. Ishiyama et al. AIP Conf. Proc. 704 (2004) Li(α,n) 11 B 8 Li+α 11 B* Excited 11 B* 11 B gr Ground 11 B gr 39

40 INHOMOGENEOUS BIG-BANG NUCLEOSYNTHESIS Kajino and Boyd, ApJ 359 (1990) 267; Orito, Kajino, Boyd & Mathews, ApJ 488 (1997) Be 7 Li(n,γ) 8 Li (n,γ) 9 Li(e - ν) 9 Be, Inhomogeneous Big-Bang 7 Li(t,n) 9 Be, 7 Li( 3 He,p) 9 Be 7 Li(n,γ) 8 Li(α,n) 11 B Standard Big-Bang 7 Li(α,γ) 11 B [O/H] 40

41 SENSITIVITY of Relevant Reactions to R-Process Sasaqui, Kajino, Mathews, Otsuki & Nakamura, ApJ (2005), in press. Y 0,r + δy r = Y 0,r {1+2σ} α (1) α(αn,γ) 9 Be 1σ = 35% (Y 0 +δy)/y 0 = (2) α(t,γ) 7 Li 1σ = 30% (3)(4) 7 Li (n,γ) 8 Li(α,n) 11 B 1σ = 35%, x (Th/Eu)=0.7 T G = 7.2 Gy! 41

42 Relevant Reactions in R-Process & SENSITIVITY Sasaqui, Kajino, Mathews, Otsuki & Nakamura, ApJ (2005) submitted. 42

43 New Waiting Points in Light-Mass Nuclei 130 In HEAVY NUCLEI β LIGHT NUCLEI 129 Cd 130 Cd 131 Cd N = 82 WAITING (α,n) Both (n,γ) and (α,n) are FAST enough so that 18 C waits for β-decay. β NEW WAITING 43

44 Neutron-Capture Cross Section σ( 18 C(n,γ) 19 C) [µb] EXPERIMENT Coulomb Dissociation (Virtual Photon) 100 Nakamura et al. PRL83 (1999) THEORY Hausser-Feshbach Estimate Extended Hausser-Feshbach 44

45 Abundance Evolution of Carbon Isotopes Sasaqui et al. (2005) 16 C(α,n) 19 O 18 C(α,n) 21 O Abundance Y A 19 C 100 Time (sec) 45

46 SENSITIVITY of 232 Th & 235,238 U to 18 C(α,n) 21 O Sasaqui, Kajino, Mathews, Otsuki & Nakamura, ApJ (2005) in press Gy Th/Eu-Chronometer 6.47 Gy 46

47 We detected ν s, then NEUTRON STAR once formed! Can core-collapse supernova produce R-PROCESS elements like 232 Th(τ 1/2 =14.05Gy) which is an celestial cosmic clock? SN1987A Why hasn t PULSAR yet been observed in this SN-remnant for more than 18 years? Did BLACK HOLE form after ν-emission? 47

48 Neutrino Luminosity If the Black Hole forms, the ν emission is t c = cutoff time CUT OFF! time = 0 SN ν - Kamiokande (1987) time = 0 48

49 ν -CUTOFF EFFECT ON ACTINOID early cutoff ABUNDANCE late cutoff no cutoff A 49

50 Neutrino Effects on Black Hole vs. Neutron Star Formation Sasaqui, Kajino & Balantekin 2005, ApJ, in press. (astro-ph/ ) Pauli Blocking important! umimportant! A = 4 He! Early ν - cutoff :- makes them impotent! :- keeps neutron-rich! important! unimportant: p has gone! -1 <

51 Sasaqui, Kajino & Balantekin 2005, ApJ, in press, (astro-ph/ ) R-elements in Black-Hole vs. Neutron Star Formation BLACK HOLE FORMATION Th Eu τ dyn = 5 ms OBSERVED BAND NEUTRON STAR FORMATION t CUT 51 (sec)

52 Different Supernova-Flow (τ dyn ) Models BLACK HOLE FORMATION UNIVERSAL SCALING OBSERVED BAND t CUT (sec) NEUTRON STAR 52 FORMATION

53 SUBARU Telescope HDS Honda et al. 2004, ApJ 607, 474 Why scatter? BH formation? AGE of these oldest stars 0 Gy 15 Gy older 53

54 Conclusions Core-collapse supernovae are the viable astrophysical sites for the r-process nucleosynthesis. We still needs more precise nuclear physics data for light-to- Intermediate as well as heavy mass neutron-rich nuclei: Some new key reactions: α(αn,γ) 9 Be, α(t,γ) 7 Li, 7 Li(n,γ) 8 Li, 8 Li(α,n) 11 B Key data: S n, β-lives, ν-induced n-emission and fission rates. New concept of SEMI-WAITING: (n, γ) and (α, n) reactions are fast enough to wait for β-decay on 8 Li, 15 B, 16, 18 C, 24 O, We studied the neutrino cutoff effect due to the Black-Hole formation in core-collapse supernovae. The r-process drastically changes if τ dyn < t CUT, making maximal effect on the 232 Th and 235,238 U. Detection of this effect in SN1987A ejecta is highly desirable to find a signature for the Black Hole formation. 54