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X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes

X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes Rutgers University. Why X-rays?. Ly a lines of all species from C (0.368 keV) to Zn (9.3 keV) kT ~ 10 6 K to 10 8 K from shocks in ejecta and CSM/ISM. ASCA. W49B. S. Si. Ar. Ca. Fe.

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X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes

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  1. X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes Rutgers University Carnegie Symposum

  2. Why X-rays? • Lya lines of all species from C (0.368 keV) to Zn (9.3 keV) • kT ~ 106 K to 108 K from shocks in ejecta and CSM/ISM ASCA W49B S Si Ar Ca Fe Carnegie Symposum

  3. X-ray Emission/Atomic Processes Continuum emission – thermal bremsstrahlung: Line emission: Abundance of element Z Ionization fraction of ion i Carnegie Symposum

  4. Abundance Determination Issues • Thermodynamic State • Nonequilibrium Ionization (NEI) (net~105 cm-3 yr) • T, n evolution with time/radius (e.g., Sedov) • Other effects: • Heating/cooling in pure element ejecta • Te/Tp • Nonthermal particles (rates and excitation) • Absolute abundances (e.g., Si/H, O/H, Fe/H) • Rely on assumption of H/He-dominated continuum • Relative abundances (e.g., Mg/Si, O/Fe) • OK, if species have the same spatial distribution Carnegie Symposum

  5. Ejecta Mass Determination Issues • Volume estimation • Clumping (reduces actual mass) • Distance (M~D5/2) • Source of electrons • Measure EM = nenIV • Solar abundance: ne ~ nH ~ nFe/107.6-12 ~ 25000nFe • Pure Fe: ne ~ 20nFe • Inferred Mpure Fe /Msolar ~ 35 Carnegie Symposum

  6. Where do we find ejecta? • Optical: SNRs with high velocity oxygen-rich features Galactic: Cas A, G292.0+1.8, Puppis A LMC/SMC: N132D, E0540-69.3, E0102.2-72.2 Other: an unresolved SNR in NGC 4449 • Remnants of historical SNe e.g., SN1006, SN1572 (Tycho), SN1604 (Kepler) Based on [Fe II] in absorption; X-ray spectra • Ejecta-dominated SNRs e.g., W49B, G352.7-0.1, G337.2-0.7, G309.2-0.6 Based on X-ray spectra (mostly ASCA) • Nearly all remnants up to ages of at least ~10,000 yrs!!! N49, N63A, DEM71, N49B, and E0103-72.6 Based on Chandra spectro-imaging Carnegie Symposum

  7. Core Collapse Supernovae • SN II, SN Ib/c (Zwicky & Baade 1934) • Massive stars that explode with (SN II) or w/out (SN Ib/c) their H envelopes • Photodisintegration of Fe, plus electron capture on nuclei, remove central P support • Core collapses, leading to NS or BH • Core stiffens, rebounds and drives an outward moving shock • Neutrinos or jets needed to produce explosion • Mean Rate ~ 1.3 SNU Carnegie Symposum

  8. Nucleosynthesis in CC SNe • Hydrostatic nucleosynthesis • During hydrostatic evolution of star • Builds up shells rich in H, He, C, O, and Si • Amount of C, O, Ne, Mg ejected varies strongly with progenitor mass • Explosive nucleosynthesis • Some mechanism drives a shock wave with 1051+ erg through the Fe-core • Burning front T’s of ~109 K cause explosive O- and Si-burning • Only affects the central parts of the star – outer layers retain their pre-SN composition Carnegie Symposum

  9. Explosive Nucleosynthesis Carnegie Symposum

  10. Overturning Our View of Cas A Hughes, Rakowski, Burrows, and Slane 2000, ApJL, 528, L109. Carnegie Symposum

  11. Cas A - Doppler Imaging by XMM • Similar velocity structures in different lines • SE knots blueshifted • N knots redshifted • Tight correlation between Si and S velocities • Fe • Note velocity distribution in N • Extends to more positive velocities than Si or S Willingale et al 2002, A&A, 381, 1039 Carnegie Symposum

  12. Cas A – 3D Ejecta Model “Plane of the sky” “Rotated” Red: Si Ka Green: S Ka Blue: Fe Ka Circle: Main shock Fe-rich ejecta lies outside Si/S-rich ejecta Carnegie Symposum

  13. Oxygen-Rich SNR G292.0+1.8 Park et al 2001, ApJL, 564, L39 Carnegie Symposum

  14. Oxygen-Rich SNR G292.0+1.8 Ejecta Rich in O, Ne, and Mg, some Si [O]/[Ne] < 1 No Si-rich or Fe-rich ejecta Carnegie Symposum

  15. Oxygen-Rich SNR G292.0+1.8 Normal Composition, CSM Central bright bar – an axisymmetric stellar wind (Blondin et al 1996) Thin, circumferential filaments enclose ejecta-dominated material – red/blue supergiant wind boundary Carnegie Symposum

  16. Thermonuclear Supernovae • SN Ia (Hoyle & Fowler 1960) • No hydrogen, a solar mass of 56Ni, some intermediate mass elements (O, Mg, Si, S,…) • Subsonic burning (deflagration) of approx. one Chandrasekhar mass of degenerate C/O • C-O white dwarf accreting H/He-rich gas from a companion • No compact remnant • Mean rate ~ 0.3 SNU Carnegie Symposum

  17. Identifying Remnants of SN Ia Tycho • Balmer-dominated SNRs (partially neutral ISM) • Ejecta abundances (Si and Fe rich, poor in O and Ne) • Remnant structure (uniform ISM, “smoother” ejecta, little spectral variation) E0509-67.5 Carnegie Symposum

  18. SN Ia Spectra and Abundances • Comparison to models • O, Ne, Mg: relatively low • Si, S, Ar, Ca: consistent • Fe: very low (<0.1) • Other spectral results • Fe: co-spatial with Si, but hotter and lower net W7: Nomoto et al 1984, Thielemann et al 1993 WDD1: Iwamoto et al 1999 NEI fit: Warren et al 2003 Carnegie Symposum

  19. ISM Abundances of the LMC • Using SNRs as a probe of the ISM • 7 SNRs, ages from 2,000 yr to 20,000 yr • Data from ASCA • Spectra calculated for evolutionary models (Sedov solution) • spatial variation • temporal variation Carnegie Symposum

  20. LMC SNRs: Integrated Abundances From fits to ASCA global X-ray spectra of 7 evolved LMC remnants N49B DEM L71 Hughes, Hayashi, & Koyama 1998, ApJ, 505, 732 Carnegie Symposum

  21. LMC Metal Abundances HHK95: ASCA X-ray SNRs Duf84: UV/Optical spectra H II regions (Dufour 1984) RD92: F supergiants (Mg, Si, Fe) (Russell & Bessel 1989) H II regions, SNRs (O, Ne, S) (Russell & Dopita 1990) Carnegie Symposum

  22. DEM L71 • Middle-aged SNR • 36” (8.7 pc) in radius • 4,000 yrs old • Rims: LMC composition • Core: [Fe]/[O] > 5 times solar • Ejecta mass: 1.5 Msun SN Ia ejecta Hughes, Ghavamian, Rakowski, & Slane 2003, ApJ, 582, L95 Carnegie Symposum

  23. N49B • Middle-aged SNR • 80” (19 pc) in radius • 5000-10,000 yrs old • Bright and faint rims • LMC composition • ISM density varies by x10 • Ejecta • Revealed by equivalent-width maps • Mg & Si rich, no strong O or Ne Park, Hughes, Slane, Burrows, Garmire, & Nousek 2003, ApJ, submitted. Carnegie Symposum

  24. SNR 0103-72.6 • Middle-aged SNR • 87” (25 pc) in radius • >10,000 yrs old (?) • Circular rim • SMC composition • Central bright region • O, Ne, Mg, Si-rich ejecta • No Fe enhancement Park, et al 2003, ApJ, in prep. Carnegie Symposum

  25. Summary • Core Collapse SNe • Cas A • X-ray ejecta dominated by Si, S, and Fe • explosive nucleosynthesis • Extensive mixing and overturning of ejecta layers • G292.0+1.8 • X-ray ejecta dominated by O, Ne, and Mg (no Fe) • Ambient medium strongly modified by progenitor • Contains “normal” young pulsar and its wind nebula Highly Structured Ejecta/Environment Carnegie Symposum

  26. Summary • Thermonuclear SNe (Tycho, E0509-67.5) • X-ray ejecta dominated by Si, S, and Fe • Stratification (most of the Fe core unshocked) • Fe: higher kT, lower net – due to: • evolution (ejecta density profile) • radioactivity • Ejecta relatively smooth and symmetric • only factor of 2 intensity variations • little spectral variation • few (one or two) clumps of Fe-rich ejecta Carnegie Symposum

  27. Summary • Evolved LMC SNRs • Global X-ray abundances consistent with optical/UV values • Individual SNRs show obvious signs of ejecta • DEM L71: 4,000 yrs, Si and Fe-rich SN Ia ejecta • N49B: 5,000-10,000 yrs, Mg and Si-rich ejecta • E0103-72.6: 10,000+ yrs, O, Ne, and Mg-rich ejecta • Issues for nucleosynthesis models • O/Ne ratio < 1 (G292.0+1.8) • O,Ne/Mg << 1 (N49B) Carnegie Symposum

  28. THE END Carnegie Symposum

  29. SN Ia Spectra and Abundances Carnegie Symposum

  30. Properties of DEM L71 Ejecta • Outer rim: lowered abundances, ~0.2 solar (LMC ISM) • Core: enhanced Fe abundance, [Fe]/[O] > 5 times solar (ejecta) • Thick elliptical shell, 32” by 40” across (3.9 pc by 4.8 pc) • Dynamical mass estimate Wang & Chevalier 2001 r’ ~ 3.0 Mej = 1.1 Mch (n/0.5 cm-3) • EM mass estimate EM ~ ne nFe V MFe < 2 Msun • Main error: source of electrons Fe-rich, low mass SN Ia Carnegie Symposum

  31. N63A • Middle-aged SNR • 34” (8.2 pc) in radius • 2000-5000 yrs old • 2nd brightest LMC SNR • “Crescent”-shaped features • Similar to features in Vela • Clumps of high speed ejecta • Not ejecta dominated • Triangular hole • X-ray absorption • Approx. 450 solar mass cloud • On near side • No PSR or PWN • LX < 4x1034 erg s-1 Warren, Hughes, & Slane, ApJ, in press (20 Jan 2003) Carnegie Symposum

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