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

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

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

SN Rates, Florence SNe maximum “Branch normals”

SN Rates, Florence SNe 20 days after maximum “Branch normals”

SN Rates, Florence SNe Ia: late-time spectra Mazzali et al Δm15(B)

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

SN Rates, Florence 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

SN Rates, Florence 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)

SN Rates, Florence 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

SN Rates, Florence 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

SN Rates, Florence Need a few blobs or a thick torus

SN Rates, Florence Use blobs to fit spectra

SN Rates, Florence 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

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

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

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

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

SN Rates, Florence 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)

SN Rates, Florence 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.

SN Rates, Florence 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

SN Rates, Florence 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

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

SN Rates, Florence Spectra also reproduced Mazzali et al daysMax

SN Rates, Florence Using Zorro to reconstruct Phillips’ Rel’n Use composition to compute LC parameters Derive Phillips Relation

SN Rates, Florence Using Zorro to reconstruct Phillips’ Rel’n Use composition to compute LC parameters  Derive Phillips Relation 

SN Rates, Florence 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)

SN Rates, Florence 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