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Jürgen Knödlseder

Gamma-ray observations of stellar nucleosynthesis processes. Jürgen Knödlseder. Reuven Ramaty Predictions: 1976: 26 Al from ISM 1976: Lines from ISM grains. Donald Clayton Predictions: 1965: 254 Cf from Crab and SN I 1969: 56 Ni and 44 Ti from SN I 1971: 60 Fe from ISM

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Jürgen Knödlseder

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  1. Gamma-ray observations of stellar nucleosynthesis processes Jürgen Knödlseder

  2. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Reuven Ramaty Predictions: 1976: 26Al from ISM 1976: Lines from ISM grains Donald Clayton Predictions: 1965: 254Cf from Crab and SN I 1969: 56Ni and 44Ti from SN I 1971: 60Fe from ISM 1974: 22Na and e+e- from novae 1981: 7Be from novae Historical context

  3. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Isotopes of relevance to gamma-ray astronomy

  4. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Thermonuclear stellar explosions (SN Ia) • Open questions • How and where do the stars ignite (centre/off centre/surface) • How does the flame propagate (sub/supersonic) • How symmetric are the explosions? • What are the progenitor systems? • How to explain the SN Ia diversity? • Gamma-ray diagnostics • Lightcurves of lines (and Compton continua) • Line shapes Isern et al. (2008) 56Co 847 keV line Credit: F. Röpke 56Co 847 keV line Gomez-Gomar et al. (1998)

  5. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN 1998bu – the deepest Ia search ever M 96 and SN 1998bu Predicted lightcurves and upper limits Isern et al. (2008) Crédits: N. Suntzeff • M 96 at 11.3 ± 0.9 Mpc • 0.77 M of 56Ni inferred from optical lightcurve • 88 days of COMPTEL/CGRO observation • 847 keV line flux < 3.1 x 10-5 ph/cm2/s (2 sigma) • Upper limit constrains visible 56Ni mass to < 0.35 M • Only DET model excluded (but who really believed in it before?)

  6. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN 1991T – a possible Ia detection? NGC 4527 and SN 1991T COMPTEL/CGRO spectrum Morris et al. (1995) • NGC 4527 at 13-14 Mpc (HST Cepheid distance) • brighter than “normal” SNIa, early occurrence of Fe lines, more than 1 M of 56Ni? • Early occurrence of Fe lines suggests nucleosynthesis products near surface • Delayed detonation? Double detonation? White-dwarf merger? • 28 daysof COMPTEL/CGRO observation • Lichti et al. (1993): 847/1238 keV line flux < 3 x 10-5 ph/cm2/s (2 sigma) • Morris et al. (1995): 847/1238 keV line flux = (5 ± 2) x 10-5 ph/cm2/s • 42 days of OSSE/CGRO observations • Leising et al. (1995): 847/1238 keV line flux < (4.1-6.6) x 10-5 ph/cm2/s (99% conf.)

  7. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Thermonuclear supernova status Predicted lightcurves and constraints • Data still inconclusive and little constraining • Significant technological step forward required to enter physics(see talk by Peter von Ballmoos) Isern et al. (2008)

  8. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN1987A – an exciting core collapse detection The Tarantula and SN 1987A Lines ... Matz et al. (1988) Kurfess et al. (1992) … lightcurves … spectra ... Leising & Share (1990) Teegarden (1994)

  9. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN1987A – an exciting core collapse detection The Tarantula and SN 1987A Lines ... • GRS/SMM: 847 keV line from 56Co • OSSE/CGRO: 122 keV line from 57Co • First direct prove of 56Ni nucleosynthesisin a supernova • 57Ni / 56Ni isotope ratio ~1.5-2 x solar • Overall expectations fromnucleosynthesis modelling confirmed Matz et al. (1988) Kurfess et al. (1992) … lightcurves … spectra ... Leising & Share (1990) Teegarden (1994)

  10. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN1987A – an exciting core collapse detection The Tarantula and SN 1987A Lines ... • GRS/SMM: 847 keV line from 56Co • OSSE/CGRO: 122 keV line from 57Co • First direct prove of 56Ni nucleosynthesisin a supernova • 57Ni / 56Ni isotope ratio ~1.5-2 x solar • Overall expectations fromnucleosynthesis modelling confirmed Matz et al. (1988) Kurfess et al. (1992) … lightcurves … spectra ... • More than 2 years of monitoringwith GRS/SMM • Gamma-ray emission turns onearlier than expected • Requires either enhancedtransparency (“swiss cheese”) orenhanced mixing of innermostejecta in outer envelope Leising & Share (1990) Teegarden (1994)

  11. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN1987A – an exciting core collapse detection The Tarantula and SN 1987A Lines ... • GRS/SMM: 847 keV line from 56Co • OSSE/CGRO: 122 keV line from 57Co • First direct prove of 56Ni nucleosynthesisin a supernova • 57Ni / 56Ni isotope ratio ~1.5-2 x solar • Overall expectations fromnucleosynthesis modelling confirmed Matz et al. (1988) Kurfess et al. (1992) … lightcurves … spectra ... • Observation of redshifted847 keV line using GRISballoon-borne high-resolutionspectrometer • Contrasts with expected blueshift(due to absorption of gamma-raysform receeding 56Co) • Do we see 56Co bullets? • More than 2 years of monitoringwith GRS/SMM • Gamma-ray emission turns onearlier than expected • Requires either enhancedtransparency (“swiss cheese”) orenhanced mixing of innermostejecta in outer envelope Leising & Share (1990) Teegarden (1994)

  12. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 SN1987A – more to come? The Tarantula and SN 1987A Bolometric lightcurve Tomsick (2011) • Late time lightcurve well explained by positrons from the radioactive decay of 44Ti (T1/2 = 60 ± 1 yr) • 44Ti yield: (1.4 ± 0.5) x 10-4 M (Jerkstrand et al. 2011) • Expected 68/78/1157 keV line flux: 2002: 3.9 x 10-6 ph/cm2/s (84%) 2012: 3.5 x 10-6 ph/cm2/s (75%)

  13. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Unveiling the historic Galactic supernova population COMPTEL/CGRO 1157 keV line 44Ti allsky map Renaud et al. (2008) Collmar (private communication) • Cas A is the only confirmed 44Ti source detected in gamma-rays • A tentative detection in Vela (“Vela Junior”) has not been confirmed • Current upper line flux limits: ~10-5 ph/cm2/s (COMPTEL/CGRO, IBIS/INTEGRAL) • Absence of further 44Ti gamma-ray sources may start to pose problems (The et al. 2006), but we're dealing with small number statistics … • NuSTAR may detect 44Ti in known historic remnants, but unlikely will discover new historic remnants Credit: NASA/CXC/SAO/P. Slane et al. (2004)

  14. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Novae • Open questions • What are the main nucleosynthetic products of novae and how much do they contribute to the chemical evolution of the Galaxy? • What is the origin of the mixing between core and envelope, and how strong is this mixing? • How can theory explain the large ejection masses inferred from observations? • What is the link between novae and SN Ia? Are the former the progenitor of the latter? • Gamma-ray diagnostics • Abundance measurements of radioactive species Credit: David A. Hardy & PPARC • Short-lived e+ emitters:13N (t=862 s): 511 keV + continuum18F (t=158 min): 511 keV + continuum • 7Be (t=77 d): 478 keV main product for CO composition • 22Na (t=3.75 yr): 1275 keV main product for ONe composition Observational challange • Transitent 511 keV + continuum (hours) • 478/1275 keV signals faint (only novae with few 100 pc in reach) CO buffer ONe mixing Hernanz & José (2004)

  15. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Observational status Simulated e+ signal in SPI ACS Upper limits (7Be) Upper limits (22Na) • Status • Upper limits for individual novae still about one order of magnitude above expectations (22Na), even worse for 7Be • Upper limits from cumulative emission provide no better constraint than observation of individual novae • No transient e+ signal so far, and flux estimates are now reduced w/r to initial estimates Prospects • First detection(s) require either an instrument with 10-100 times better sensitivity, or a nova explosion within few 100 pc of the Sun ... Jean (private communication) Simulated 1275 keV sky Jean et al. (2000)

  16. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 V407 Cyg – the first gamma-ray nova ! Abdo et al. (2010)

  17. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Using radioisotopes as a tracer – the case of 26Al & 60Fe COMPTEL/CGRO 1809 keV line map (26Al) SPI/INTEGRAL 60Fe lines Knödlseder (1997) Wang et al. (2007) • Open questions • What are the domintant nucleosynthesis channels for 26Al and 60Fe? • Where in the Galaxy do these elements form? • How do they propagate away from their formation sites? • What do they tell us about stellar physics (stellar mixing and winds, explosion physics)? Gamma-ray diagnostics • Detailled spatial mapping of 26Al (1809 keV) and 60Fe (1173/1332 keV) decay lines • Line shifts for bulk kinematics • Line broadenings for ejecta dynamics

  18. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 26Al nucleosynthesis in the Cygnus region Radio Infrared Gamma (1809 keV) Thermal emission from gas ionized by massive stars. Emission from dust that re-radiates stellar UV photons. Radioactive decay of 26Al. • The Cygnus region is one of the massive star forming regions in our Galaxy, at less than 2 kpc from the Sun • The region is highly ionized by ~200 O stars, there is only one known SNR (gamma Cygni) in the field • The presence of a bright 1809 keV source in coincidence with one of the largest concentrations of O stars known in the Galaxy and the additional absence of SNRs provides the strongest evidence for hydrodynamic nucleosynthesis being the primary channel for 26Al formation Martin et al. (2010)

  19. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Recent news from SPI/INTEGRAL Inner Galaxy 26Al decay in Sco-Cen (?) Credit: Diehl • SPI/INTEGRAL detects 1809 keV line emission towards Sco-Cen with a flux of 6 x 10-5 ph/cm2/s • Is this consistent with COMPTEL/CGRO data? • Cygnus flux is also 6 x 10-5 ph/cm2/s, but the Cygnus region is significantly brighter in the COMPTEL image than the Sco-Cen region … and COMPTEL was more sensitive for 26Al studies than SPI is .. Diehl et al. (2006) • SPI/INTEGRAL measures 1809 keV line shifts that are consistent with being due to bulk velocity shifts as result of Galactic rotation of 26Al • This technique may ultimately allow to kinematically estimate the distance of26Al decay sites, yet so far the current sensitivity does not allow to resolve individual velocity components Martin (2008)

  20. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 A guaranteed positron source About 85% of the 26Al decays are accompanied by the emission of a positron. 1809 keV A detailed comparison of 1809 keV and 511 keV sky maps allows inferring positron propagation properties. (see talk by Pierre Jean) 511 keV

  21. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Gamma (200 MeV - 20 GeV) Ionised gas (H) LMC LMC HE : interactions of cosmic rays with ambient gas ( ~106-7 yr) The link to cosmic rays Gamma (1809 keV) Ionised gas (DMR/COBE) Massive stars: sources of ionising (UV) photons (due to high surface temp.) ( ~106-7 yr) 26Al: stellar nucleosynthesis product ( ~106 yr)

  22. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 Expectations for nearby galaxies Assumption: M26Al ~ L>100 MeV Detecting 26Al beyond the Milky Way is challenging, yet for a sensitivity of 10-6 ph cm-2 s-1 the LMC may be in reach. Detecting the LMC in 1,8 MeV gamma rays holds potential for studying the relation between massive star formation and 26Al production and diffusion/mixing. Warning: metallicity effects have not been taken into account for the estimates.

  23. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 The origin of 60Fe After 2 decades of observations, lines from 60Fe have been detected at the sensitivity limit of current instruments. Sensible imaging (à la COMPTEL 1,809 keV map) requires x10 times more signal/sensitivity. 14 ± 6% of the 1809 keV flux • 60Fe nucleosynthesis channels: • r-process (SN) Clayton (1971) • s-process (OB stars, AGB) Prantzos et al. (1987, 1989) • Carbon deflagration SN Ia (Woosley 1997) To first order, 60Fe should be distribution similar to 26Al, yet in individual star forming regions there could be some subtle time delays (e.g. Cygnus). Martin et al. (2010)

  24. J. Knödlseder, Advanced Topics in Astrophysics, A tribute to Jordi Isern in his 60th anniversary, Llafranc, 4-6 May 2011 • Gamma-ray line astrophysics holds the potential to provide valuable constraints on stellar nucleosynthesis processes. Current achieved sensitivites (at best ~10-5 ph/cm2/s for gamma-ray lines) are not sufficient to fully exploit this science potential. • Observing decay products from thermonuclear and core collapse supernovae is (still) a very attractive tool to better understand the physics of the explosions.Requires x 10 better sensitivity than COMPTEL/SPI. • Interesting news on 44Ti nucleosynthesis and young Galactic supernova remnants may soon come from the NuSTAR mission.Focusing definitely helps to gain sensitivity! • Observing radioactive decay products from novae seems difficult to achieve in the near future.Requires at least x 10, better x 100 increased sensitivity w/r COMPTEL/SPI. • We still lack an image of Galactic 60Fe radioactivity (determine the origin of Galactic 60Fe nucleosynthesis). Requires x 10 better sensitivity than COMPTEL/SPI. • Imaging of 26Al in the LMC would allow to better understand the link between massive star formation and diffusion/mixing of 26Al.Requires x 20-30 better sensitivity than COMPTEL/SPI. Summary

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