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Gamma-Ray Line Observations from Cosmic Nuclei

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Gamma-Ray Line Observations from Cosmic Nuclei Gamma-RayGamma-Ray LineLine ObservationsObservations fromfrom CosmicCosmic NucleiNuclei Roland Diehl MPE Garching • Gamma-Ray Line Astronomy: Tools, Objectives, Results • Specific Astrophysical Studies • Diffuse Radioactivity (26Al, 60Fe) • Supernovae (44Ti) • Prospects Gamma-RayGamma-Ray Astronomy:Astronomy: LinesLines ofof InterestInterest Radioactive Isotopes Decay Time > Source Dilution Time Yields > Instrumental Sensitivities Isotope Mean Decay Chain γ -Ray Energy (keV) Lifetime 7Be 77 d 7Be → 7Li* 478 56Ni 111 d 56Ni → 56Co* →56Fe*+e+ 158, 812; 847, 1238 57Ni 390 d 57Co→ 57Fe* 122 22Na 3.8 y 22Na → 22Ne* + e+ 1275 44Ti 89 y 44Ti→44Sc*→44Ca*+e+ 78, 68; 1157 26Al 1.04 106y 26Al → 26Mg* + e+ 1809 60Fe 2.0 106y 60Fe → 60Co* → 60Ni* 59, 1173, 1332 e+ …. 105y e++e- → Ps → γγ.. 511, <511 Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 Gamma-RayGamma-Ray Astronomy:Astronomy: InstrumentsInstruments 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 Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 Gamma-RayGamma-Ray Astronomy:Astronomy: MeasurementsMeasurements Satellite-Based Surveys and Balloon Experiments Pioneering Space Missions Apollo Gamma-Ray Detector (1977) HEAO-A1 (6 month sky survey, 1978/79) Balloon Experiments UCR, UNH and MPE Compton Telescopes (1978...1982) SN1987A Balloon Programs (1987) Ge Telescopes (HEXAGONE, GRIS, HIREGS) (1980-1998) Xe and Solid-State Detector Compton Telescopes (1995-...) Laue Telescopes (1998-...) Experiments for other Prime Objectives Solar Observatories (SMM, HESSI) (1985-...) “X-Ray” Missions (RXTE, BeppoSax, HETE-II) Compton Gamma-Ray Observatory OSSE & COMPTEL Gamma-Ray Line Surveys (1991-2000) Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 Gamma-RayGamma-Ray Astronomy:Astronomy: ResultsResults Live Cosmic Nucleosynthesis Detected e+ and 26Al in ISM (Haymes et al. 1976; Matteson et al. 1982) 56Ni and 57Ni in cc-SN (Matz et al. 1988; Kurfess et al. 1992) 44Ti from a cc-SN (Iyudin et al. 1994) 56Co Hints from a SN Ia (Morris et al. 1995) Cosmic Nucleosynthesis Environments Being Studied 26Al throughout the Galaxy (Diehl et al. 1995-2002) 26Al Decay at ~500 km s-1? (Naya et al. 1996) e+ Annihilation in Inner Galaxy (Purcell et al. 1997; Milne et al. 2001) 44Ti Source Limits & Constraints (Schönfelder et al. 2000; Vink et al. 2000) 56Co Limits for a SN Ia (Georgii et al. 2002) 22Na & 7Be Limits for Novae (Iyudin 1995-2002; Harris et al. 2001) 26Al & Massive Stars in Cygnus (Plüschke 2001, Cervino et al. 2002) 26Al from Orion OB1 (Diehl et al. 2002) Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 TheThe SkySky atat 18091809 keV:keV: 26AlAl Sco-Cen? Carina Vela Cygnus Inner-Galaxy Ridge Orion Auriga/α Per? Eridanus Complete CGRO Mission (Plüschke et al. 2001) Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 TheThe COMPTELCOMPTEL 26AlAl ImageImage Maximum-Entropy Method (“ME”): Global-Entropy-Damped & Misfit-Gradient Driven Iterations Towards Maximum-Likelihood Fit Multi-Resolution Expectation Maximization Method (“MREM”): Misfit-Gradient Driven and Scale-Hierarchically Noise-Damped Iterations (RL) Towards Maximum-Likelihood Fit Substantial Image ‘Noise’ (~4o FWHM!) Consolidated Galactic and Localized 26Al Sources Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 26AlAl MapsMaps && PossiblePossible SourceSource TracersTracers CO map of molecular gas IR map at 240 µm, dust Radio map at 53 GHz, free electrons Hα Emission Different Imaging Methods from Ionized (ME, MREM, MLik) Gas Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 26Al:Al: PlausiblePlausible SourcesSources && OpenOpen IssuesIssues Massive Stars are Dominating Sources (Diehl et al. 1995; Prantzos & Diehl 1996; Knödlseder 1999) Ionization Correlated to 26Al (free electrons) (Chen et al. 1995) Consistency Check on Massive-Star Outputs: Line-of-sight integrated I1.8MeV = Ifree-free_emission -5 26 Plausible ~8 10 Mo Average Yield of Al per “OV star” 26 Consistent total Al Mass of ~ 2.4 Mo Plausible ~10000 WR Stars in Galaxy But: => SN (II+Ib) rate ~ 1.8/100y (?) Agreement of 1.8 MeV Emission Distribution with Source Tracers Free-Electron Distribution (Pulsars; 53 GHz COBE) , i.e., mainly from Ionization by Massive-Star UV Photons Warm Dust Emission, i.e., from SN and Massive-Star Winds’ Heating of IS Dust (>100 µm COBE) Distribution of Known Massive Stars (i.e., Young Clusters, WR Stars, O Stars) (but: incomplete at d>3 kpc) Irregular Patterns of Massive-Star Locations Observed in LMC, M31; Same as Overall Irregularity of 1.8 MeV Emission? 26Al Disk Latitude Extent > Gas, But < Old Population (=> “puffed up” by SN/Wind Ejection?) Contributions From WR Stars, cc-SNae, Novae, AGB Stars ? Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 TheThe COMPTELCOMPTEL 26AlAl ImageImage Significances of Map Regions 0.7 37.7 3.9 12.1 13.2 6.4 5.8 7.4 Roland Diehl, Jan 2002 Complete CGRO Mission (Plüschke et al. 2001) Fits of ME Map in ROI, relative to flattened ROI Image Quality Adequate for Galactic and Localized Analyses of Counterparts Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 MassiveMassive StarStar ClustersClusters andand 26AlAl Diagnostics:Diagnostics: CygnusCygnus Candidate 26Al sources in the Cygnus region: WR stars, SNR, OB Associations (top view of Galaxy) Cygnus region OB Associations and Foreground Molecular Clouds Candidate Sources at <2.5 kpc, Relatively Well-Studied, No Bgd Sources Distance Uncertainties, Occultation (Massive-Star Census Incomplete) Bright Extended Diffuse 26Al Gamma-Ray Emission Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 ModelingModeling 26AlAl fromfrom StarStar ClustersClusters Stellar Content (OB Association Richness, IMF) Stellar Evolution Lifetime WR Phase 26Al Yields per Star yields 1.809 MeV “Light Curve” for a Massive-Star Cluster plus other Observables UV / Ionization (-> free-free Emission) Kinetic Energy / X Brightness -> Plüschke et al., 2001; Cerviño et al. 2002 Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 MassiveMassive StarStar ClustersClusters andand 26AlAl Diagnostics:Diagnostics: CygnusCygnus 26Al emission at 1809 keV (left), compared to a model map as derived from richness- corrected OB associations and individual known sources (right) The quality of the 1809 keV fit by different tracers (green) is approximately 1809 keV Images of Source Models of the Cygnus Region: the “raw” achieved with model based on known sources and OB association knowledge (left); astrophysical source the model after correction of OB association richness with CO column models after density normalized on Cyg OB2 (middle); the model after OB adjustment of their association richness correction and accounting for ejecta diffusion characteristics (blue) (right). Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 MassiveMassive StarStar ClustersClusters andand 26AlAl Diagnostics:Diagnostics: OrionOrion The COMPTEL 9-year Survey Detects Diffuse 1809 keV emission in the Orion/Eridanus Region at ~7σ significance ME-deconvolved Image: Background-subtracted Count Extended Emission Southward of the Spectra Clearly Show the 1809 keV Orion Clouds Line, Following the Features in the Image Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 MassiveMassive StarStar ClustersClusters andand 26AlAl Diagnostics:Diagnostics: OrionOrion Massive Stars of the OB1 Association Located at the Edge of the Orion Molecular Clouds Appears to Eject 26 Dust Emisssion (IRAS) and HI Al Radioactivity Trace Neutral Gas Around the into the Eridanus Eridanus Bubble, X-Ray Emission Cavity Traces Hot Gas Inside the Cavity l=210 Orion A,B Orion OB1 l=200 Eridanus Bubble l=185 Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 26AlAl SourceSource VarietyVariety inin LocalizedLocalized Regions:Regions: VelaVela Model Emissivity Along Galactic Plane COMPTEL 1.8 MeV C1-9 rod 05/2000 10.00 IR240/10 IR240/4 8.00 free-free/10 free-free/4 6.00 Model Amplitude 4.00 2.00 0.00 180 150 120 90 60 30 0 -30 -60 -90 -120 -150 -180 Galactic Longitude Interesting Nearby Sources in front of Vela Molecular Ridge Vela SNR (d~250 pc) γ2Velorum (WR11) (d~258/400pc) RXJ0852 (200pc<d<1500pc) Extended Diffuse 26Al Emission None of These Sources Clearly Seen in 26Al Roland Diehl Nuclei in the Cosmos VII, Fuji-Yoshida, 12 July 2002 26AlAl fromfrom Supernovae:Supernovae: HelpHelp fromfrom 60Fe?Fe? Production in SNae (and Stars) through n Capture on 56,58Fe (s-Process; 13C/22Ne(α,n)) 26Al/60Fe Flux Ratio Limits 0.60 R Diehl 1/99 01/1999: new bgd model; 0.3 syst error, 2sig stat error Decay Time 2 Myr + SN Yields -> 0.50 0.40 Al) Predicted from Theory Iγ ~0.16 Iγ for 26Al from SN only 26 60Fe 26Al 0.30 Fe)/I( 60 0.20 60Fe from 26Al Sources? I( 0.10 0.00 COMP'99 COMPTEL GRIS SMM OSSE 60Fe in Oceanic Crust => Nearby
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