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Exploring the global properties of SNe Ia

Exploring the global properties of SNe Ia. Paolo A. Mazzali Max-Planck Institut f ϋ r Astrophysik, Garching Astronomy Department and RESearch Centre for the Early Universe, University of Tokyo Istituto Naz. di Astrofisica, OATs. Spectra of Supernovae: the photospheric phase.

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Exploring the global properties of SNe Ia

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  1. Exploring the global properties of SNe Ia Paolo A. Mazzali Max-Planck Institut fϋr Astrophysik, Garching Astronomy Department and RESearch Centre for the Early Universe, University of Tokyo Istituto Naz. di Astrofisica, OATs

  2. Spectra of Supernovae:the photospheric phase SN Ia SN II SN Ic SN Ib Galileo Galilei Institute

  3. SNe Ia have similar light curvesAre they also equally luminous? Branch & Tammann 1992 Galileo Galilei Institute

  4. 87 SNe Ia: Observed B Light Curves Galileo Galilei Institute

  5. 87 SNe Ia: Normalised B Light Curves Galileo Galilei Institute

  6. 87 SNe Ia: Stretched B Light Curves Galileo Galilei Institute

  7. The Phillips Relation (Absolute Magnitude - Decline Rate) Phillips 1992 Galileo Galilei Institute

  8. Cosmology with SNe Ia Distant SNe are FAINT for their redshift From B.Schmidt Galileo Galilei Institute

  9. Cosmology with SNe Ia Riess et al. 1999 Galileo Galilei Institute

  10. empty universe fainter • High-z SN Search Team • (Riess et al. 1998) • Supernova Cosmology Project • (Perlmutter et al. 1999) brighter nearer further SN Ia as distance indicators • surprising result: • Distant SNe Ia appear fainter • than standard candles in an • empty Friedmann model • of the universe! • SN Ia luminosity distances • indicate • accelerated expansion! • Are SNIaStandard Candles • independent of age? • Or is there some evolution • of SN Ia luminosity with age? • Spectroscopy is a • powerful tool to • search for differences! Galileo Galilei Institute

  11. Cosmology with SNe Ia: the Cosmological Constant From E.Baron Galileo Galilei Institute

  12. Bolometric Light Curves Contardo et al. 2000 Galileo Galilei Institute

  13. Soon after explosion (first few weeks), ejecta density is high enough for a `pseudo-photosphere’ to form. “Photospheric Epoch” (early time) P-Cygni Profiles superposed on continuum Later on, photosphere disappears as densities decrease. “Nebular Epoch” (late time) Emission-line spectrum Supernova Spectra evolve Galileo Galilei Institute

  14. SNIa Spectral Evolution Gomez & Lopez 1998 Galileo Galilei Institute

  15. Homologous expansion (v ≈ R) Ejecta are dense “Photospheric Epoch” Early-time spectrum absorption continuum τ=1 Galileo Galilei Institute

  16. Early-time spectrum • Lines have P-Cygni profiles with But velocities are high: many lines overlap: “Line Blanketing” Galileo Galilei Institute

  17. SNe Ia @ maximum “Branch normals” Galileo Galilei Institute

  18. SNe Ia @ 20 days after maximum “Branch normal” Galileo Galilei Institute

  19. Late-time spectra Spectrum: no continuum. Emission line profiles depend on velocity, abundance distribution. Homologous expansion, homogenous density and abundance: parabolic profiles Ejecta are thin: “Nebular Epoch” Gas heated by deposition of γ’s and cooled by forbidden line emission τ < 1 Galileo Galilei Institute

  20. SNe Ia: late-time spectra Δm15(B) 1.93 1.77 1.27 1.51 0.87 Mazzali et al. 1998 Galileo Galilei Institute

  21. Thermonuclear SNe (Type Ia)White Dwarf in BinarySystem WD accretes H until MWD~1.4M⊙, T~109K • Thermonuclear burning (C burning) to NSE • Explosion (KE~1051 erg) • Total disruption of WD • 56Ni produced (~0.7M⊙) RG CO-WD C,O Si, S 56Ni Galileo Galilei Institute

  22. Type Ia SN 1996X spectral evolution Salvo et al. 2000 Galileo Galilei Institute

  23. The Classical SN Ia explosion model: W7 Branch et al. 1985 Galileo Galilei Institute

  24. I. Using observables to understand SNe Ia Questions • Properties of SNe Ia (eg Phillips rel’n) • Mode of explosion (deflagration, delayed detonation, other even less reasonable modes…) • Cosmology? Methods • Look at/model spectra & light curves Galileo Galilei Institute

  25. What we need • Excellent photometric and spectroscopic coverage of a number of nearby SNe Ia • Comparison with the high-z sample • 3D models of the explosion Galileo Galilei Institute

  26. How we get it: the EU-RTN • 16 well observed SNe (2002-2006)  Abundance Tomography  More signatures of CSM interaction Galileo Galilei Institute

  27. Data: SNe 2002bo, 2003du Galileo Galilei Institute

  28. Modelling early-time spectra Monte Carlo code • Composition • Density • Luminosity • Velocity Galileo Galilei Institute

  29. Abundance Stratification • Model sequence of spectra to derive composition layering • How did the star burn? Stehle et al 2005 Galileo Galilei Institute

  30. Model late-time spectra Monte Carlo LC code + NLTE nebular code • No radiative transfer • Get full view of inner ejecta (56Ni zone) • Estimate masses Galileo Galilei Institute

  31. Composion in a typical SN Ia • Elements more mixed than in typical 1D models Galileo Galilei Institute

  32. Test: Light Curve Monte Carlo code • Use W7 density • Composition from tomography • (56Ni ~0.50M⊙ )  Model LC matches data very well Galileo Galilei Institute

  33. II. Outer regions of the ejecta: HVFs • Nearly all SNe show very high velocity (~20000 km/s) absorption features (HVF) in Ca II (some also in Si II) Galileo Galilei Institute

  34. HVFs come in various forms Mazzali et al. (2005) Tanaka et al. (2006) Galileo Galilei Institute

  35. What makes the HVFs • Abundance enhancement unlikely • Density enhancement more reasonable • Ejection of blobs or CSM interaction? • Blobs: line profiles depend on orientation Galileo Galilei Institute

  36. Distribution of HVFs • Any model should reproduce the observed distribution of HVF wavelength (blob velocity) and strength (optical depth, covering factor) • Single blob does not Galileo Galilei Institute

  37. Need a few blobs or a thick torus Galileo Galilei Institute

  38. Use blobs to fit spectra Galileo Galilei Institute

  39. 3D Simulations (MPA) Reinecke et al. 2000 Galileo Galilei Institute

  40. III. The Global View • Late time spectra suggest M(56Ni)  Δm15(B) [ M(Bol)]  v(Fe) Galileo Galilei Institute

  41. Role of 54Fe, 58Ni • Stable Fe group isotopes radiate but do not heat • Some anticorrelation between 56Ni and (54Fe, 58Ni) • Very good correlation beween Σ(NSE)andΔm15(B) Galileo Galilei Institute

  42. Composition Layering • Outer extent of Fe zone varies ( Δm15(B), Lum) • Inner extent of IME matches outer extent of Fe • Outer extent of IME ~ const. Galileo Galilei Institute

  43. Include 54Fe, 58Ni: “Zorro” diagram A basic property of SNe Ia Mass probably constant Amount of burned material also probably constant • KE ~ const • What does it all mean? • Delayed detonation? • Multi-spot ignited deflagration? • Other possibilities….? Galileo Galilei Institute

  44. IV. Role of Fe-group, IME on LC • 56Ni: light, opacity, KE • 54Fe, 58Ni: opacity, KE • IME: KE, (some opacity) • CO (if any): little opacity Galileo Galilei Institute

  45. Explaining Phillips’ Relation • 56Ni: light, opacity, KE Reproduce • 54Fe, 58Ni: opacity, KE Phillips’ Relation • IME: KE, (some opacity) • CO (if any): little opacity (Mazzali et al. 2001) Galileo Galilei Institute

  46. Spectra @ -7 days Mazzali et al. 2001 Galileo Galilei Institute

  47. Spectra @ Maximum Mazzali et al. 2001 Galileo Galilei Institute

  48. Spectra @ +15 days Mazzali et al. 2001 Galileo Galilei Institute

  49. Using Zorro to reconstruct Phillips’ Rel’n • Use composition to compute LC parameters  • Derive Phillips Relation  Galileo Galilei Institute

  50. Effect of 54Fe, 58Ni • Amount of 54Fe, 58Ni may be a fn. of WD metallicity (Timmes et al. 2003) • Ratio 56Ni/NSE affects light, not KE or opacity • LCs w/ different peak brightness, same decline rate • May explain spread in Phillips’ Relation. Galileo Galilei Institute

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