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Modeling Ejecta in Supernova Remnant X-Ray Spectra John P. Hughes Rutgers University

Modeling Ejecta in Supernova Remnant X-Ray Spectra John P. Hughes Rutgers University. Parviz Ghavamian, Rutgers Pat Slane, CfA Sangwook Park, Penn State Gordon Garmire, Penn State Anne Decourchelle, Saclay. Cara Rakowski, Rutgers Jessica Warren, Rutgers Dave Burrows, Penn State

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Modeling Ejecta in Supernova Remnant X-Ray Spectra John P. Hughes Rutgers University

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  1. Modeling Ejecta in Supernova Remnant X-Ray SpectraJohn P. HughesRutgers University • Parviz Ghavamian, Rutgers • Pat Slane, CfA • Sangwook Park, Penn State • Gordon Garmire, Penn State • Anne Decourchelle, Saclay • Cara Rakowski, Rutgers • Jessica Warren, Rutgers • Dave Burrows, Penn State • John Nousek, Penn State • Peter Roming, Penn State SNoRe Cambridge, MA

  2. Where’s the 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 SNoRe Cambridge, MA

  3. 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 SNoRe Cambridge, MA

  4. SN Ia Integrated Yields Iwamoto et al, 1999, ApJS, 125, 439 SNoRe Cambridge, MA

  5. SN Ia Yields vs. Radius Mass (Msun) O 0.056-0.143 Ne 0.0008-0.0045 Mg 0.027-0.0158 Si 0.142-0.279 Fe 0.648-0.834 Iwamoto et al, 1999, ApJS, 125, 439 SNoRe Cambridge, MA

  6. 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 SNoRe Cambridge, MA

  7. 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 SNoRe Cambridge, MA

  8. Explosive Nucleosynthesis SNoRe Cambridge, MA

  9. Typical Mass Fractions SNoRe Cambridge, MA

  10. Major Yields (in Solar Masses) SNoRe Cambridge, MA

  11. SN II Yields vs. Radius 20 Msun model Hydrostatic nucl. M>2.05 Explosive nucl. ~1.6 <M<2.05 Mass cut set so 0.075 Msun of Fe is ejected Thielemann, Nomoto, and Hashimoto, 1996, ApJ, 460, 408 SNoRe Cambridge, MA

  12. Uncertainties • Thermonuclear SNe • Physics of flame front propagation • Precise progenitor system unknown – rate of accretion and composition unknown • Core Collapse SNe • Explosion mechanism unknown • Location of mass cut (compact object/ejecta) • Convection during He-burning • 12C(a,g)16O reaction rate SNoRe Cambridge, MA

  13. Useful General References • Trimble 1982, Rev Mod Phy, 54, 1183 (Supernovae Part I) • Trimble 1983, Rev Mod Phy, 55, 511 (Supernovae Part II) • Bethe 1990, Rev Mod Phy, 62, 801 (Supernova Mechanisms) • Arnett 1996, “Supernovae and Nucleosynthesis” (Princeton University Press: Princeton) • Wallerstein et al, 1997 Rev Mod Phy, 69, 995 (update of B2FH) SNoRe Cambridge, MA

  14. X-ray Emission/Atomic Processes Continuum emission – thermal bremsstrahlung: Line emission: Abundance of element Z Ionization fraction of ion i SNoRe Cambridge, MA

  15. Abundance Determination Issues • Thermodynamic State • Nonequilibrium Ionization (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 particle (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 SNoRe Cambridge, MA

  16. 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 SNoRe Cambridge, MA

  17. Overturning Our View of Cas A Hughes, Rakowski, Burrows, and Slane 2000, ApJL, 528, L109. SNoRe Cambridge, MA

  18. Oxygen-Rich SNR G292.0+1.8 Park et al 2001, ApJL, 564, L39 SNoRe Cambridge, MA

  19. 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 SNoRe Cambridge, MA

  20. 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 winbd boundary SNoRe Cambridge, MA

  21. Oxygen-Rich SNR G292.0+1.8 Point source Featureless power-law spectrum, photon index = 1.7 Surrounded by diffuse X-ray/radio nebula Off center, implied speed of ~800 km/s SNoRe Cambridge, MA

  22. PSR J1124-5916 in G292.0+1.8 • Discovered at Parkes (Camilo et al 2002) • P=0.1353140749 s, dP/dt=7.471E-13 • Characteristic age ~ 2900 yrs (SNR age ~ 1600 yrs) • Not detected in coherent FFT of Chandra HRC observation • 3.5 sigma detection from Zn2 test at radio parameters • Only ~130 pulsed events in 50 ks SNoRe Cambridge, MA

  23. PSR J1124-5916 • Image Analysis: point source and elliptical gaussian (small nebula) • Point source contains ~160 X-ray events • Pulsed fraction high ~80% • Unpulsed point source emission < 1.4E-3 cts/s • LBB< 1033 erg/s Below standard cooling curve for 2000 yr old PSR SNoRe Cambridge, MA

  24. DEM L71: Ejecta and Shock Physics Chandra/NASA Rutgers Fabry-Perot/NOAO Hard X-ray H alpha Soft X-ray Hughes, Ghavamian, Rakowski, and Slane, ApJL, 582, in press (10 Jan 2003) SNoRe Cambridge, MA

  25. Fe-Rich Ejecta SNoRe Cambridge, MA

  26. 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 SNoRe Cambridge, MA

  27. DEM L71: Shock Physics Nonradiative Balmer-dominated shock Measure post-shock proton temperature X-ray emission from thermal bremsstralung Measure post-shock electron temperature SNoRe Cambridge, MA

  28. Nonradiative Balmer Shocks • Nonradiative means that a radiative (cooling) zone does not form • Low density (partially neutral) gas • High velocity shocks • Narrow component: cold H I overrun by shock, collisionally excited • Broad component: hot postshock protons that charge exchange with cold H I (Chevalier & Raymond 1978; Chevalier, Kirshner, & Raymond 1980) Width of broad component yields post shock proton temperature Ghavamian, Rakowski, Hughes, and Williams 2002, ApJ, submitted. SNoRe Cambridge, MA

  29. Constraining the Electron Temperature • Fit NEI shock models to 3 spatial zones to follow evolution of Te • Study 5 azimuthal regions with sufficient Chandra statistics and broad Halpha component • Available data cannot constrain Te gradients • Data do determine mean Te • Suggest partial to compete temperature equilibration Rakowski, Ghavamian, Hughes, & Williams 2002, ApJ, submitted. SNoRe Cambridge, MA

  30. Results on Te/Tp from DEM L71 • Shows trend for higher equilibration for lower speed shocks • X-ray/Halpha results consistent with other purely Halpha ones SNoRe Cambridge, MA

  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) SNoRe Cambridge, MA

  32. N49B • Middle-aged SNR • 80” (19 pc) in radius • 5000-10,000 yrs old • Near N49 • Bright and faint rims • LMC composition • Varying ISM density • No PSR or PWN • LX < 3x1034 erg s-1 • Magnesium-rich ejecta • Equivalent-width maps • No O or Ne enhancement Park, Hughes, Slane, et al. ApJ, in prep. SNoRe Cambridge, MA

  33. SNR 0103-72.6 • Middle-aged SNR • 87” (25 pc) in radius • >10,000 yrs old (??) • 2nd brightest SMC SNR • No PSR or PWN • LX < 4x1034 erg s-1 • Circular outer shock • Low SMC-type abundances • Why so circular? • Central excess • Apparently O, Ne, Mg rich ejecta Park, Hughes, et al., ApJ, in prep. SNoRe Cambridge, MA

  34. THE END SNoRe Cambridge, MA

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