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

2. SN Rates, Florence22.5.20082 Obs.Rel.1: The Phillips Relation (Absolute Magnitude - Decline Rate) Phillips 1992

3. SN Rates, Florence22.5.20083 O.R. 2: Bolometric Light Curves Contardo et al. 2000 Lpeak - decline rate or LC shape

4. SN Rates, Florence22.5.20084 SNe Ia @ maximum “Branch normals”

5. SN Rates, Florence22.5.20085 SNe Ia @ 20 days after maximum “Branch normals”

6. SN Rates, Florence22.5.20086 SNe Ia: late-time spectra Mazzali et al. 1998 Δm15(B) 1.93 1.77 1.27 1.51 0.87

7. SN Rates, Florence22.5.20087 O.R.3: Nebular line width - decline rate after Mazzali et al. 1998 56 Ni mass and distribution and decline rate (≡Luminosity) are related

8. SN Rates, Florence22.5.20088 OR4: Velocity Gradients: an alternative SN Ia classification Benetti et al. (2005): Classify SNeIa according to rate of change of post-maximum photospheric velocity of SiII 6355  3 SN groups: High Velocity Gradient Low Velocity Gradient Faint Groups separate out in v-ΔM 15 (B) plot

9. SN Rates, Florence22.5.20089 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) Mazzali et al (2005)

10. SN Rates, Florence22.5.200810 HVFs trace the outer explosion What makes the HVFs? Abundance enhancement unlikely Density enhancement more reasonable (incl. H) Ejection of blobs or CSM interaction? Blobs: line profiles depend on orientation

11. SN Rates, Florence22.5.200811 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

12. SN Rates, Florence22.5.200812 Need a few blobs or a thick torus

13. SN Rates, Florence22.5.200813 Use blobs to fit spectra

14. SN Rates, Florence22.5.200814 III. Abundance Stratification Model spectral sequence to derive composition layering: explore the depth of the star  How did the star burn? Stehle et al 2005

15. SN Rates, Florence22.5.200815 Modelling late-time spectra Full view of inner ejecta ( 56 Ni zone) Monte Carlo LC code + NLTE nebular code No radiative transfer Estimate masses

16. SN Rates, Florence22.5.200816 Result: Composition in a typical SN Ia SN 2002bo  m 15 (B)=1.15 (average) Elements more mixed than in typical 1D models

17. SN Rates, Florence22.5.200817 Test: Modelling Light Curve Monte Carlo code Use W7 density Composition from tomography 56 Ni ~0.50M   Model LC matches data very well

18. SN Rates, Florence22.5.200818 IV. The Global View Late time spectra suggest M( 56 Ni)  Δm 15 (B) [  M(Bol)]  v(Fe)

19. SN Rates, Florence22.5.200819 Role of 54 Fe, 58 Ni Stable Fe group isotopes radiate but do not heat Some anticorrelation between 56 Ni and ( 54 Fe, 58 Ni) Very good correlation beween Σ(NSE) and Δm 15 (B)

20. SN Rates, Florence22.5.200820 Composition Layering Outer extent of NSE zone varies (  Δm 15 (B), Lum) Inner extent of IME matches outer extent of NSE Outer extent of IME ~ const.

21. SN Rates, Florence22.5.200821 Putting it all together: “ orro” diagram A basic property of SNe Ia Mass burned ~ constant  Progenitor mass also probably constant: M Ch  KE ~ const What does it all mean? Delayed detonation? Multi-spot ignited deflagration? Other possibilities….? Stable 54Fe, 58Ni 56 Ni IME Mazzali et al. (2006), Science

22. SN Rates, Florence22.5.200822 The Role of Fe-group, IME on LC 56 Ni: light, opacity, KE 54 Fe, 58 Ni: opacity, KE IME: KE, some opacity CO (if any): little opacity

23. SN Rates, Florence22.5.200823 V. Explaining the Phillips’ Relation Models with increasing 56 Ni content reproduce Phillips’ Relation (Mazzali et al. 2001)

24. SN Rates, Florence22.5.200824 Spectra also reproduced Mazzali et al. 2001 -7daysMax

25. SN Rates, Florence22.5.200825 Using Zorro to reconstruct Phillips’ Rel’n Use composition to compute LC parameters Derive Phillips Relation

26. SN Rates, Florence22.5.200826 Using Zorro to reconstruct Phillips’ Rel’n Use composition to compute LC parameters  Derive Phillips Relation 

27. SN Rates, Florence22.5.200827 Effect of stable NSE ( 54 Fe, 58 Ni) Amount of 54 Fe, 58 Ni may be a fn. of WD metallicity (Timmes et al. 2003) Ratio 56 Ni/NSE affects light, not KE or opacity  LCs w/ different peak brightness, same decline rate  May cause spread about the Phillips’ Relation. (Mazzali & Podsiadlowski 2006)

28. SN Rates, Florence22.5.200828 Conclusions There is some regularity among SNe Ia (surprise surprise…) Ejecta reflect stratified composition of models Total mass burned may be constant 56 Ni determines luminosity (not new) Total NSE determines LC shape Degree of neutronization can give rise to dispersion in luminosity-decline rate relation Z evolution may confuse cosmological parameters