Roland Diehl. MPE Garching

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1 Gamma-Ray Astronomy Roland Diehl MPE Garching Astrophysical Objects & Nuclear Physics Supernova and Nova Issues, Observations, Nuclear Physics Aspects Diffuse Radioactivities and Positron Annihilation Applications for Cosmic-Rays and Near Compact Objects Prospects in Astronomy Instrumentation

2 Astronomical Observations throughout the e.m. Spectrum Radio- Waves Infrared Radiation Optical Light UV Radiation X-Rays Gamma-Rays 100km 50km 10km Reflection CO 2,H 2 O,O 3... Absorption Bands due to O 3, N, O log 10 log 10 λ

3 Gamma-Ray Astrophysics: Basic Processes Physical Source Processes at kev GeV:

4 Astrophysical Cycles of Matter M~ M o 10 8 y condensation dense molecular clouds star formation (~3%) interstellar medium stars y M > 0.08 M o infall y dust dust winds SN explosion mixing Galactic halo outflow SNR's & hot bubbles y ~90% SNIa compact remnant (WD, NS,BH) Associate Radiation Source Processes with Desired Astrophysical Parameter Roland Diehl e.g. Stellar-Atmosphere Abundance <-> SN Physics VISTARS Workshop, Russbach (A), 7 March 2005

5 Astrophysics and Nuclear Physics Nuclear Reactions in Cosmic Environments Nucleosynthesis Radioactive Isotopes Elemental Abundances in Stars and ISM (SNR), IGM Excited Nuclei Cosmic Ray Population Environment of Compact Stars Models for Astrophysical Object Types Supernovae Type Ia Core Collapses Black Holes, Neutron Stars, Sun

6 Relevant Astronomical Observations Abundances of Elements (Isotopes) Optical Absorption/Emission Lines Stellar and Supernova Atmospheres Interstellar and Intergalactic Gas (ionized, neutral) X-Ray Emission Lines Supernova Remnants Interstellar & Intergalactic Gas Gamma-Ray Lines Supernovae and Young Supernova Remnants Interstellar Gas Broad-Band Emission Characteristics & Energy Budgets Supernovae Gamma-Ray Bursts Neutron Stars Black-Hole Candidates

7 Gamma-Ray Astronomy: Instruments Photon Counters and Telescopes Simple Detector (& Collimator) (e.g. HEAO-C, SMM, CGRO-OSSE) Spatial Resolution (=Aperture) Defined Through Shield Coded Mask Telescopes (Shadowing Mask & Detector Array) (e.g. SIGMA, INTEGRAL) Spatial Resolution Defined by Mask & Detector Elements Sizes Focussing Telescopes (Laue Lens & Detector Array) (CLAIRE, MAX) Spatial Resolution Defined by Lens Diffraction & Distance Compton Telescopes (Coincidence-Setup of Position-Sensitive Detectors) (e.g. CGRO-COMPTEL, LXeGRiT, MEGA, ACS) Spatial Resolution Defined by Detectors Spatial Resolution Achieved Sensitivity: ~10-5 ph cm -2 s -1, Angular Resolution deg

8 INTEGRAL Successfully Launched! 17 October 2002: INTEGRAL on its way (as planned) 12:00 INTEGRAL safely on its way, all systems normal 08:35 Both solar wings successfully deployed 08:13 Separation of Integral from upper stage 06:50 Separation of upper stage and Integral from third stage 06:41 Launch of Integral

9 INTEGRAL Orbit Goals Minimize Cosmic-Ray Activation Background Variations Maximize Science Observing Time Highly Eccentric 72-hour orbit Inclination 51.6 o Perigee 9078km, Apogee km 90% Above 40000km Realtime Telemetry (->GRB!) Launch Proton, From Baikonur Ground Stations Redu (Belgium ) Goldstone (California)

10 The INTEGRAL Spectrometer (SPI) Coded-Mask Telescope 19 Ge Detectors (5.5x5.5x7cm) BGO Anticoincidence Detector & Shield Stirling Cryocooler Energy Range kev Energy Resolution ~ kev Angular Resolution ~2 arcmin Field-of-View 16x16 o Timing Resolution 52 µs

11 Maintaining High Spectral Resolution Degradation ~2% per Orbit, ~20% in 6 Months (@1 MeV) ~35% Slower at 85K Annealing: 126(36) hrs at 105C Few hrs at 90K 12 Feb Jul Nov 2003 FWHM = *rev

12 SPI Sensitivity for Gamma-Ray Lines 3σ narrow line sensitivity (photons s -1 cm -2 ) HEAO3 OSSE SPI COMPTEL T obs = 10 6 s E (MeV) 1 The early estimate had ignored the instrumental line contributions Pulse Shape Rejection of background is less effective than estimated

13 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 Isotope Mean Lifetime Decay Chain γ -Ray Energy (kev) 7 Be 77 d 7 Be 7 Li* Ni 111 d 56 Ni 56 Co* 56 Fe*+e + 158, 812; 847, Ni 390 d 57 Co 57 Fe* Na 3.8 y 22 Na 22 Ne* + e Ti 89 y 44 Ti 44 Sc* 44 Ca*+e + 78, 68; Al y 26 Al 26 Mg* + e Fe y 60 Fe 60 Co* 60 Ni* 59, 1173, 1332 e y e + +e - Ps γγ.. 511, <511

14 Radioactive Material Measurements Gamma-Rays Penetrate ~g/cm 2 (Galaxy=transparent) Weak Decay -> No Excitation Function Gamma-Ray Intensity Independent from T, ρ, Radioactive Decay Gamma-Ray Flux and Radioactive Mass M X A Z Known Distance -> Radioactive Mass Known Source Yield -> Source Distance Known Distance & Yield -> Age of Event [ M Θ ] = I γ [ ph cm 2 sec 1 N = N 0 e t τ 2 4πd τa 1pc ] n N γ A 2 2 [ cm] 1yr[sec] M [ g] Θ

15 Specific Studies & Results

16 A Hot Issue : Are SNIa Standard Candles? Branch, 1998; 2003 Spectra and Light Curves are Surprisingly Homogeneous (after normalization by decline in B band) Need a Well-Regulated Process/Event Type, Producing Much Fe Diversity Can Be Recognized, Nevertheless

17 What Makes a Supernovae Ia SN Ia Models Close Binary System WD Giant White Dwarf Merger Binary Mass Transfer WD at M Ch C/O Layer He Layer SN Ia Central C Ignition He Shell Flash

18 How Does a SNIa Explode? C Ignition at M Ch Limit (possibly many ignition points) Turbulent Flame Propagation WD Expansion -> Flame Extinction Issues: Rapid Time Scales! Nuclear Burning C+O-> 56 Ni Expansion Mixing

19 Variations of a Thermonuclear WD Explosion Flame Propagation Slow Flame Fizzles, Fast Flame at ρ>10 7 g cm -3 Yields Ni Only Deflagration -> Detonation Transition Chemical Composition of Accreted Matter Accretion Rate C/O (WD Merger): Rapid C Burning. But: Accretion-Induced Collapse or SN? He: off-center C Detonation after He Flash H: Accumulation of Matter? (M ej(nova) ~M accr ) Build-Up Fuel Layer for Explosion. How Slow? -> Fe/Ca Element Ratio -> Sub-Ch Progenitors -> Sub-Ch Progenitors -> Supersoft XRS e.g.h: Novae (dm/dt < 10-9 M o yr -1 )? Flashes? Steady Burning? Common Envelope (dm/dt > 10-6 M o yr -1 )? e.g.he: 10-9 < dm/dt < 5x10-8 M o yr -1 Need Sufficient WD s for SNIa Event Rate Key Measurements: E kin, E radioactive (Ni Mass, Envelope Structure), Ejecta Composition

20 Gamma-Rays from Supernovae Ia Rarely SNIa 56 Ni Decay Gamma-Rays are Above Instrumental Limits (~10-5 ph cm -2 s -1 ) COMPTEL ~2 Events / 9 Years CGRO ~2 Events / 2 Years INTEGRAL Mission Signal from SN1991T (3σ) (13 Mpc) Upper Limit for SN1998bu (11 Mpc) The 56 Ni Power Source -0.5 M o of 56 Ni?? Which Model?

21 X-Rays from Young SNR: SNIa Diagnostics Imaging plus Spectroscopy Map Spatial Distribution of Elements After Explosion Tycho SNR: Images in Elemental Lines (XMM, top) Hi-Res Image (Chandra, bottom)

22 Core Collapse-Supernovae: Model Shell-Structured Evolved Massive Star Gravitational Core Collapse Supernova Shock Wave Shock Region Explosive Nucleosynthesis Proto-Neutron Star Neutrino Heating of Shock Region from Inside Explosion Mechanism = Competition Between Infall and Neutrino Heating 3D-Effects Important for Energy Budget AND Nucleosynthesis

23 Nuclear-Physics Issues in CC-Supernova Models 45 Sc(p,γ) 46 Ti 3D-Effects Important for Energy Budget AND Nucleosynthesis Location of Ejecta/Remnant Separation? 44 Ti Produced at r < 10 3 km from QSE/Si-Burning & α-rich Freeze-Out, => 44 Ti Gamma-Rays are Unique Probe (+Ni Isotopes)

24 Core-Collapse Collapse Supernovae: 44 Ti from Cas A τ =89y, EC 44 Ti 44 Sc τ = 5.4 h, β + 44 Ca Detections: Iyudin et al. 1994: COMPTEL MeV Vink et al. 2001; 2005: SAX & IBIS 68/78 kev Comparable Upper Limits by RXTE, OSSE 44 Ti Decay: τ~89y Difficult γ-ray Region (78, 68, 1157 kev) -> Young SNR -> Uncertain I γ, I X -> 44 Ti Ejected Mass ~ M o

25 Cas A: A Well-Studied Young Nearby SNR Chandra ISO XMM-Newton ~330 year-old SNR at ~3.4 kpc Massive Progenitor (10-25 M o ) Filaments, Fast Ejecta (knots), Fe-rich Clumps, No Onion-Shell- Like Elemental Morphology, Jet: Asymmetric Explosion 44 Ti (and 56 Ni) Ejection Unseen SN -> CSM Dust Central Object (NS/BH?) => (?) Core Collapse SN with Unusual Asymmetries? 44 Ti Emission Affected by Ionization? HST

26 44 Ti Decay in a Young SNR 44 Ti Decay: e Capture -> Ionization!?! E ion,k =6.6 kev, E ion,l =1.6 kev SN Composition Profile: Fe & Ti Similar Fe/Ti Clump Ionization by Reverse Shock 44 Ti Decay Rate Modifications: Inhibit Early, -> Enhance Later (wrt 44 Ti Mass / Exponential Decay) Days Days Cas A 44 Ti Mass ~ as Predicted by Theory? 44 Ti EC, τ~89y 44 Sc EC/β, τ~5.4h 44 Ca

27 44 Ti Emission from cc-sne: Open Issues Consistency of Cas A cc-sn Model: 44 Ti from Models/SN1987A/γ-Rays: ~ M o 44 Ti Ejection Should Be Correlated to High-Entropy Material -> a-rich Freeze-Out Large Explosion Energy Large Mass of Ejected 56 Ni (Bright Supernova) Only in aspherical explosions?

28 44 Ti Emission from cc-sne: Open Issues Consistency of Cas A cc-sn Model: 44 Ti from Models/SN1987A/γ-Rays: ~ M o 44 Ti Ejection Should Be Correlated to High-Entropy Material -> a-rich Freeze-Out Large Explosion Energy Large Mass of Ejected 56 Ni (Bright Supernova) No 44 Ti Sources in Inner Galaxy Parent Distribution of Sources ~ 26 Al Monte-Carlo Study -> 44 Ti SNR Number Low Small-Number Statistics? Observational Bias? Metallicity Anticorrelation? The et al., 2000 Can 44 Ti Sources Reveal... Inner SN Velocity Profiles? Ionization-Inhibited Decay (EC)? ( 44 Ti Line Shape!) Asymmetric Core Collapses?

29 Novae Classical Novae: Accreting WD in Binary System Runaway H Burning with Nuclear Processing of Upper WD Layer (p process) Ejection of ~10-4 M o Issues: Burning Time Profile Fuel Composition and Mixing Ejected Mass Nuclear Reactions

30 Nova Diagnostics with Nuclear Lines CO Nova (1 kpc; 0.8 M o ) O-Ne Nova (1 kpc; 1.2 M o ) Brief Annihilation Flash β Decay Continuum (before optical nova!) 22 Na Radioactivity (O-Ne Novae)

31 Nova Gamma-Ray Light Curves Need Sky Survey Optical Nova (=discovery) After Characteristic Gamma- Ray Signals Hernanz et al.,

32 The Sky at 1809 kev: 26 Al Sco-Cen? Auriga/α Per? Cygnus Inner-Galaxy Ridge Carina Vela Orion Eridanus Superimposed Nucleosynthesis Sources (10 6 Years) Complete CGRO Mission (Plüschke et al. 2001)

33 26 Al Maps & Possible Source Tracers synchrotron radiation thermal dust emission free-free radiation Different Linear Combinations of Narrow-Band Radio Maps (WMAP) Different Imaging Methods (ME, MREM, MLik)

34 26 Al Line Shape Astrophysics SN dust formation ejecta ISM SNR & Wind Bubbles ISM thermal turbulent Re-accelerated (CR) 26 Al velocity Ejection and Slowing-Down of 26 Al from Sources 26 Al Ejected into Hot Cavities (WR Winds, ) -> ISM Turbulence <-> Line Width 26 Al Condensed on Dust, Re-accelerated -> High-Velocity Tail? Chen et al. 1997; Sturner & Naya 1999 Galactic Rotation 26 Al Sources in Spiral Arms, Along Line-of-Sight -> 26 Al Source Location Along LoS Gehrels et al. 1996; Kretschmer et al. 2003

35 Imaging Spectroscopy with SPI: Al Line Shape ~ 3 Msec of Observations of Inner Galaxy Search Signal Amplitude in Fine Energy Bins, Assuming ~Galactic-Plane Distribution Gaussian Fit COMPTEL 26 Al Map (-180 o +180 o / -10 o +10 o ) GeSat bgd; scale per kev,det The Galactic 26 Al Line is not significantly broadened Gaussian with Width of instrumental Bgd Feature Gaussian with Width of effective instrumental Resolution Gaussian with Width of best-achieved instrumental Resolution

36 The 26 Al Line Width GRIS (Naya 1996) RHESSI (Smith 2003) SPI (Diehl et al 2003) Broad Line was Difficult to Understand, Seems not Confirmed Cygnus Region May Show ISM Turbulence SPI; in Cygnus (Knödlseder et al 2004) SPI preliminary (Diehl et al 2005)

37 Nucleosynthesis in the Current Galaxy: 26 Al Astrophysics: 26 Al Reflects Sources of Nucleosynthesis (τ~10 6 y) COMPTEL Imaging -> Massive Stars are Dominating Sources Source Complexes: Decay in ISM -> narrow line Large Cavities -> broad line Young Clusters -> broad line INTEGRAL/SPI Results: Narrow Line in Inner Galaxy SPI COMPTEL SPI GRIS s 540km s -1 result (difficult, for τ=10 6 y) Somewhat Broadened Line in Cygnus Region (~200 km s -1 ) WR-Wind Dominated (v WR ~10 3 km s -1, d~pc) Ejecta in Hot/Turbulent Phase & pre-blown Bubbles

38 60 Fe Radioactivity Gamma-Rays Production in Supernovae and Massive Stars Neutron Capture on 56,58 Fe (s-process) n Sources: 13 C(α,n) 16 O (He Burning) 20 Ne(α,n) 23 Na (O/Ne Burning) Locations: CC-Supernova O/Ne Shell and Bottom of He Shell Giant Phase of Massive Star He Shell, C Shell Astrophysical Significance: Identify Dominating 26 Al Sources Core-Collapse Supernovae Identical Diffuse-Emission Morphologies of 26 Al Line and 60 Fe Lines Images Wolf Rayet Phase of (M 25-40M o ) Stars No 60 Fe from 26 Al Sources I 60Fe-lines /I 26Al-line Prediction (?) for SN Origin: ~0.16 (MeV Lines) ~0.03 (59 kev Line) 60 Fe 60 Co 60 Ni τ =2.0 My β - (2%) τ = 5.3 y γ β - 59 kev γ MeV γ MeV

39 Terrestrial 60 Fe Detections Current Terrestrial Record Ocean Crust Analysis Slow, Fe-rich Growth (2mm/My) Dating with CR-Produced 10 Be AMS Atom Counting Nearby SN 2.8 My ago? Knie et al. 2004

40 Interstellar 60 Fe: Gamma-Ray Constraints Upper Limits, and two tentative detections RHESSI (2.6σ), SPI (3σ)

41 60 Fe: The Puzzle Model Predictions Prantzos 2004 γ-rays No Source Would Bring the 60 Fe/ 26 Al Gamma-Ray Intensity Ratio Close to Measurement Constraints! (~Factor 5!) Nuclear Physics? Model Sample Statistics? Uncertainties: n Capture Cross Sections for Fe Isotopes β Decay Rate for 59 Fe Development of Hot-Base He Shell, C Shell n Source Activation

42 Positrons from Nuclear Reactions (<2001) Annihilation 511 kev OSSE Map of Inner Galaxy e+ Budget: Nucleosynthesis (β + decays) Pulsars & Jet Sources Other Exotic Sources? CGRO-OSSE ref s: Purcell et al. 1997; Kinzer et al. 1998; Milne et al. 1999

43 Annihilation of Positrons in the Galaxy Astrophysics: Positron-Source Variety in Inner Galaxy Nucleosynthesis Sources (SNIa, ) Pulsars, Binaries, Jet Sources Light Dark Matter Annihilations Annihilation in Diluted ISM (τ~10 5 y) Results (INTEGRAL / SPI) : instrumental bgd line Lonjou et al Annihilation in Hot ISM Jean et al kev Line Characteristics : I = ph cm -2 s -1 -> Annihilation Rate (@GC) s -1 e+ annihilation line: kev; MaxEnt +20 Strong et al Broadened Line: Deconvolved FWHM = 2.76 kev Expectation: Hot-ISM->~4 kev, Grains->~2 kev -> Annihilation in Warm ISM Phase 511 kev Line Emission Morphology: Extended, ~bulge-like Emission (δl~18 o,δb~13 o ) All-sky map; Richardson-Lucy, Smoothed Knödlseder et al No/Weak Disk Emission Seen; No Fountain -> Young Stars make Minor Contribution Old stellar population! Dark-Matter Annihilations?

44 Gamma-Ray Lines from Cosmic Nuclei: Summary Live Cosmic Nucleosynthesis Detected. More? ISM: e + 26 Al 60 Fe; SNae: 56 Ni, 57 Ni, 44 Ti 22 Na? Cosmic Nucleosynthesis Environments Being Studied 26 Al and e + Annihilation 44 Ti 5 44 Ti Decay Gamma-ray Fluxes from Cas A 4 I * 10-5 ph cm -2 s COMPTEL 1999 OSSE 1996 RXTE 1997 SAX Ni

45 Instrumental Sensitivities for Gamma-Ray Lines Courtesy S. Boggs, 2003

46 Gamma-Ray Lines from Cosmic Nuclei: Prospects Astrophysics: Origin of 26 Al, e+, 60 Fe -> Massive Stars and SNae Core Collapse SNae: Inner Explosion, Asymmetries Thermonuclear SNae: Deflagration/Detonation Transition Novae: Progenitor Evolution, Mixing? Radioactive Ejecta? Cosmic-Ray Acceleration -> Excitation Lines Observatories: Gamma-Ray Line Shapes -> INTEGRAL Surveys at Improved Sensitivity Deep SN Measurements -> MEGA, ACT -> Laue Tel.

47 Gamma-Ray Lines from Cosmic Nuclei: Summary Live Cosmic Nucleosynthesis Detected. More? ISM: e + 26 Al 60 Fe; SNae: 56 Ni, 57 Ni, 44 Ti 22 Na? Cosmic Nucleosynthesis Environments Being Studied 26 Al and e + Annihilation 44 Ti 5 44 Ti Decay Gamma-ray Fluxes from Cas A 4 I * 10-5 ph cm -2 s COMPTEL 1999 OSSE 1996 RXTE 1997 SAX Ni