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Nuclear Astrophysics

Nuclear Astrophysics. Roland Diehl Nuclear Astrophysics Science Issues Specific Sub-Topics: Status, Challenges, Requirements Next Steps for Gamma-Ray Astronomy Missions. The Key Science Questions of Nuclear Astrophysics.

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Nuclear Astrophysics

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  1. Nuclear Astrophysics Roland Diehl Nuclear Astrophysics Science Issues Specific Sub-Topics: Status, Challenges, Requirements Next Steps for Gamma-Ray Astronomy Missions

  2. The Key Science Questions of Nuclear Astrophysics • How are the elements and isotopes formed, which we see throughout the universe? • How do nuclear transmutations affect the sites where they occur?

  3. Key Science Question 1: The Cosmic Abundance Pattern factor 100000! factor 100000! • How are the elements and isotopes formed, which we see throughout the universe?

  4. Key Science Question 1: (current-day frontier)Cosmic Nuclear Reaction Dynamics QSE Network: Si Burning 45Sc(p,g)46Ti • How are the elements and isotopes formed, which we see throughout the universe? • Nuclear-Reaction Dynamics • Specific Isotopic Abundances as “Calibration Marks” Cas A @ 1.157 MeV: 44Ti (T1/2~59y)

  5. Key Science Question 2: (e.g.:) Stellar Evolution • How do nuclear transmutations affect the sites where they occur? Stars are gravitationally- confined thermonuclear reactors Stellar structure <-> Nuclear-reaction physics

  6. Key Science Question 2: (current-day frontier)Cosmic Explosions • How do nuclear transmutations affect the sites where they occur? 500 msec (=fast!) R~10000km) • SNIa - HOW? • Explosive C Burning • Flame Propagation Dynamics • Issues: • Rapid Time Scales • Huge Range in Spatial Dimensions

  7. Key Science Question 1: The Present Status • How are the elements and isotopes formed, which we see throughout the universe? • Basics ~known (“processes”) • Details ~poorly understood: (e.g.) • SNIa Fe yield 0.5 ±0.4 Mo • Unknown sites for r-process(es), p nuclei synthesis • Unknown relevant nuclear-reaction rates • Uncertain relevance of neutrino reactions (ccSN) • Stability of heavy nuclei (deformations, skin,…?) • Cosmic-ray nucleosynthesis (LiBeB) contribution uncertain • …

  8. Nuclear Reaction Uncertainties in Astrophysics 82 126 50 Quenched 82 28 20 50 protons neutrons 8 28 2 20 8 2 New Effects: EC in initial cc-SN: n shells partly occupied at finite (SN) temperature Experimentally-Unaccessible Reactions: Target and Projectile areRadioactive/shortlived

  9. Key Science Question 2 in Nuclear Astrophysics • How do nuclear transmutationsaffect the sites where they occur? • Basics ~known (“stellar phases”, “explosions”) • Details ~poorly understood • SNIa lightcurves vs. composition and GCE • Shell burnings in massive stars and AGB • Explosive C burning in SNIa • Explosive shell burnings in SNII • Burried C burning in Type-I XRB Superbursts • …

  10. Key Science Question 2: (current-day frontier)Cosmic Explosions, Stars Quenched protons neutrons • How do nuclear transmutations affect the sites where they occur? • SNIa: • Nuclear-Burning Front • CC-SN: • p+e->n initial collapse • Stars: • Stellar Core Sizes <-> • 12C(a,g)16O

  11. Key Science Question 2: (current-day frontier) Stellar Structure in Late Phases • Episodes of Core and Shell Burning • Impacts on Pre-SN Core Size & Composition • Nucleosynthesis Products

  12. Key Science Questions: Interested? If we want to go beyond empirical models of the effects of • Sources of nucleosynthesis -> chemical evolution • Stellar structure & explosions -> object/event frequencies then we need to proceed investigating the nuclear physics in cosmic environments ~MeV Gamma-rays are a “natural” messager • (nuclear binding energies)

  13. Key Science Questions: Relevant? • If we want to go beyond current nuclear astronomy data of • Gamma-ray observatories (survey @10-5 ph cm-2 s-1; E/dE~500) • Indirect methods (e.g. inferred abundances from meteorites, recombination) • then we must identify the uniqueness of cosmic gamma-rays in nuclear-astrophysics topics

  14. “Cosmic Vision” in Nuclear Astrophysics • We seek understanding of cosmic phenomena in terms of nuclear-physics • We want to add new qualities to existing astronomy

  15. Gamma-Ray Lines for Nucleosynthesis Study • Radioactive Trace Isotopes as Nucleosynthesis By-Products • For Gamma-Spectroscopy We Need: • Decay Time > Source Dilution Time • Yields > Instrumental Sensitivities

  16. Status and Issues,in more detail • Thermonuclear Supernovae (56Ni) • Core Collapse Supernovae (56Ni, 44Ti) • Novae (22Na, 7Be, e+) • Cumulative Nucleosynthesis • Cosmological (56Ni) • Massive Stars (26Al, 60Fe) • Supernovae and Novae (e+ annihilation)

  17. Thermonuclear Supernovae (SNIa) SN1991T Morris et al. ‘95 • Rarely SNIa 56Ni Decay Gamma-Rays are Above Instrumental Limits (~10-5 ph cm-2 s-1) • ~2 Events captured / 9 Years CGRO • Signal from SN1991T (3s) (13 Mpc) • Upper Limit for SN1998bu (11 Mpc) • ~2 Candidate Events / 2 Years INTEGRAL • Gamma-Ray Results: • Controversial • Exceptional Events (1991T)? • Systematic Uncertainty too Large!

  18. Thermonuclear Supernovae (SNIa) 20d, 5Mpc DET DEL DEF SUB Close Binary System SN IaProgenitor Models Giant WD White Dwarf Merger Binary Mass Transfer C/O Layer He Layer • Issues • The 56Ni Power Source: 0.5 Mo of 56Ni?? • Which Progenitor Path? • Which Explosion Model? WD at MCh He Shell Flash SN Ia Central C Ignition

  19. Gravitational Core Collapse Supernova Shock Wave Shell-Structured Evolved Massive Star n n n n n n n n n n n n n n n n n n n n n n n n n-heated Shock Region Explosive Nucleosynthesis Proto-Neutron Star Neutrino Heating of Shock Region from Inside Core Collapse-Supernovae: Model Empirical / Parametrized Models for Explosion(Explosion Energy, Mass Cut) • Explosion Mechanism = Competition Between Infall and Neutrino Heating • 3D-Effects Important for Energy Budget AND Nucleosynthesis

  20. Core Collapse Supernovae: 56Ni and 44Ti • Consistency of cc-SN Model: Cas A vs. … • 44Ti from Models/SN1987A/g-Rays • 44Ti Correlation to • Large Explosion Energy • Large Mass of 56Ni (Bright Supernova) Aspherical explosions?? (->GRB) Need Event Statistics, 44Ti Spectra

  21. Core Collapse Supernovae: 60Fe  =2.0 My - (2%)  59 keV  = 5.3 y -  1.173 MeV  1.332 MeV 60Fe 60Co 60Ni • Neutron Capture on 56,58Fe • n Sources: • 13C(a,n)16O (He Burning) • 20Ne(a,n)23Na (O/Ne Burning) • Sites/Locations: • CC-Supernova O/Ne Shell and Bottom of He Shell • Giant Phase of Massive Star He Shell, C Shell • Astrophysical Significance: Clarify SN Nuclear-Reaction Parameters (multi-paramter issue!): • CC-SN Shell Structure • n Capture from Fe-Group Elements-> r-process feeding

  22. Novae CO Nova (1 kpc; 0.8 Mo) O-Ne Nova (1 kpc; 1.2 Mo) • None SeenYet • Need <<2kpc • 511 keV Flash survey • Brief Annihilation Flash • b Decay Continuum (before optical nova!) • 22Na Radioactivity (O-Ne Novae)

  23. SNIa Cosmology with Gamma-Rays • Cosmological SN Fill in ~MeV Emission to Diffuse Background (‘gap’ between AGN and Blazars; SN lines + redshift-> characteristic cont) • SN rate (z>5), SNIa/cc-SN ratio (z; SNIa delay)

  24. Massive Stars: 26Al COMPTEL Plüschke et al. 2001 SPI SPI Diehl et al. 2005 Knödlseder et al. 2004 • Nucleosynthesis in the Current Galaxy (t~106y) • Massive Stars are dominating sources • COMPTEL imaging • Massive-Star clusters of “right age” are 26Al-bright • Population synthesis • Nucleosynthesis products from massive-star clusters ejected into ISM cavities • COMPTEL Orion • SPI Line Shapes • Astronomical window to massive-star activity

  25. “26Al Astronomy” ISM ISM thermal turbulent SN dust formation SNR & Wind Bubbles Re-accelerated (CR) ejecta 26Al velocity OB stars 26Al brightness Eridanus superbubble • Massive-Star Clusters • Characteristic 26Al Lightcurve 3-7 My, WR->SNe-> Cluster Ages • ISM Properties Near 26Al Sources • 26Al Ejected into Hot Cavities (WR Winds, …)-> ISM Turbulence <-> Line Width-> 26Al Source Offset from Clusters • 26Al Condensed on Dust, Re-accelerated-> High-Velocity Tail? Orion OB1 Plüschke et al. 2001

  26. Galactic Astronomy of 26Al Sources deZeeuw et al. 1999 Starforming Complexes (Russeil 2003) Galaxy Nearby Groups of Stars

  27. The 60Fe Puzzle      g-rays  Prantzos 2004 • No Source Would Bring the 60Fe/26Al Gamma-Ray Intensity Ratio Close to Measurement Constraints! (~Factor 5!) • Nuclear Physics? • Model Sample Statistics? Model Predictions Uncertainties: • n Capture Cross Sections for Fe Isotopes • b Decay Rate for 59Fe • Development of Hot-Base He Shell, C Shell • n Source Activation

  28. Lonjou et al. 2004 Jean et al. 2005 Annihilation in Hot ISM instrumentalbgd line All-sky map; Richardson-Lucy, Smoothed Knödlseder et al. 2004 Annihilation of Positrons in the Galaxy • Positron-Source Variety • Nucleosynthesis Sources (SNIa, …) • Pulsars, Binaries, Jet Sources • Light Dark Matter Annihilations • Annihilation in Diluted ISM (t~105y) Status (INTEGRAL / SPI): • Annihilation Rate (@GC) 1.4 1043 s-1 • Annihilation in Warm ISM Phase • Extended 511 keV Line Emission • Extended, ~bulge-like Emission (dl~8o,db~7o) • Weak Disk Emission; No “Fountain” -> Young Stars make Minor Contribution • Old stellar population! • Dark-Matter Annihilations?

  29. Positron Annihilation: Prospects All-sky map; Richardson-Lucy, Smoothed Knödlseder et al. 2004 • After INTEGRAL: • Annihilation emission mapped throughout the Galaxy • Inner-Galaxy 511 keV line shape well-measured • Issues: • Other galaxies? • Point sources? • Specific regions with known sources? • Dark matter constraints?

  30. Unique Nuclear-Astrophysics Info from Gamma-Rays • SNIa: • Absolute Amount of 56Ni Radioactivity • Progenitor Type • Inner Explosion Kinematics • CC-SNe: • Inner Core of SN Explosion (near mass cut) • Shell Structure and Explosive Burning • n Capture on Fe-Group Nuclei • Novae • Progenitor Evolution, Burning-Zone Mixing • Cumulative Nucleosynthesis • Cosmic SNIa Rate • Massive-Star Group Nucleosynthesis • ISM Around Massive Stars at 106y Time Scale • Positron Transport in ISM/Galaxy

  31. Future Telescopes for Gamma-Ray Lines • Laue Lens Photon Concentrator P. von Ballmoos et al. -> “MAX” • Advanced Compton Telescope • Steve Boggs et al. -> “Elemental Origins Probe”

  32. Instrumental Sensitivities for Gamma-Ray Lines Advanced Compton Telescope Courtesy S. Boggs, 2003

  33. Unique Nuclear-Astrophysics Info from Gamma-Rays • SNIa: • Absolute Amount of 56Ni Radioactivity • Progenitor Type • Inner Explosion Kinematics • CC-SNe: • Inner Core of SN Explosion (near mass cut) • Shell Structure and Explosive Burning • n Capture on Fe-Group Nuclei • Novae • Progenitor Evolution, Burning-Zone Mixing • Cumulative Nucleosynthesis • Cosmic SNIa Rate • Massive-Star Group Nucleosynthesis • ISM Around Massive Stars at 106y Time Scale • Positron Transport in ISM/Galaxy

  34. Key Science in Nuclear Gamma-Ray Astrophysics • Understand Supernova Explosions • Exploit “Line Astronomy” in 26Al and e+ Annihilation

  35. Unique Nuclear-Astrophysics Info from Gamma-Rays • SNIa: • Absolute Amount of 56Ni Radioactivity • Progenitor Type • Inner Explosion Kinematics • CC-SNe: • Inner Core of SN Explosion (near mass cut) • Shell Structure and Explosive Burning • n Capture on Fe-Group Nuclei • Novae • Progenitor Evolution, Burning-Zone Mixing • Cumulative Nucleosynthesis • Cosmic SNIa Rate • Massive-Star Group Nucleosynthesis • ISM Around Massive Stars at 106y Time Scale • Positron Transport in ISM/Galaxy • ?? +++ +++ ++ +++ ++ + + + +++ +++ ++

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