the theoretical understanding of
Type Ia Supernovae
Daniel Kasen
Supernova Discovery History
Asiago Catalog (all supernova types)
SN cosmology“super-nova”
Supernova FactoryLick observatory SN searchCfA SN groupCarnegie SN projectESSENCESupernova Legacy Survey
Supernova Discovery Future
Rough predictions and promises…
PanStarrsDark Energy SurveyJDEMLarge Synoptic Survey Telescope (LSST)
ProposedDark Energy Measurements
Systematic error, not statistical error, is the issue (e.g., luminosity evolution)
Aim for Type Ia SNe as reliable standard candles to a few %
SN Ia ProgenitorsAccreting white dwarf near the Chandrasekhar
limit
Accretion rate:10-7 Msun / year
White Dwarf IgnitionKuhlen, Woosley, and Glaitzmeier (2006)
QuickTime™ and aYUV420 codec decompressor
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t = 0.0 sect = 0.5 sect = 1.0 sec
3D Deflagration ModelSubsonic turbulent flame burning
t = 1.5 sec
Roepke et al. (2005)
C/O
boom
Fe
56Ni
Si/S/Ca
C/O
Type Ia Supernova Light Curves
powered by the beta decay: 56Ni 56Co 56Fe
Type Ia Supernova Spectrum
20 days after explosion
Spectroscopic Homogeneity and Diversity
monitoring silicon expansion velocitiesfrom Leonard et al, ApJ 2006
Type Ia Width-Luminosity Relation
brighter supernovae have broader light curves
Supernova Ejecta Opacity
blending of millions of line transitions
FeII bound-boundFeIII bound-bound
free expansion
Light Curves / Spectra(~100 days)
radioactive decay / radiative transfer
Type Iasupernovatheoreticalsimulation challenge
ignition
Presupernova Evolution(~100-109 years)
accreting, convective white dwarf
Explosion (~1-100 secs)
turbulent nuclear combustion / hydrodynamics
Observations
DOE: Scientific Discovery through Advanced Computing (SciDAC)
The “Computational Astrophysics Consortium” (CAC) Stan Woosley (PI)
UC Santa Cruz, UC Berkeley, Stanford, Arizona, Stony Brook, JHU,LANL, LLNL, LBNL
Models
3-dimensional Time-Dependent Monte Carlo Radiative Transfer
SEDONA CodeExpanding atmosphereRealistic opacitiesThree-dimensionalTime-dependentMulti-wavelengthIncludes spectropolarizationIncludes radioactive decay and gamma-ray transferIterative solution for thermal equilibrium
Kasen et al 2006 ApJ
Large Scale Computing
Jacquard, NERSC
Incite award, Oak Ridge Lab: 4 million hours/yearAtlas “grand challenge” LLNL: 4 million hours/yearNERSC award, LBL: 3 million hours/year
Fe
56Ni
Si/S/Ca
C/OGrid of Type Ia Supernova Modelsw/ Stan WoosleySergei BlinikovElena Sorokina
130 one-dimensionalChandrasekhar massmodels with varied composition
ParametersMFe
MNi
MSi
“mixing”MFe + MNi + MSi + Mco = MCH
Broadband Synthetic Light Curves
Model Compared to observations of SN 2001el
Kasen (2006) ApJ
ParametersMFe = 0.1 Msun MNi = 0.6 Msun
MSi = 0.4 Msun
Kasen, ApJ 2006
Day 35 after explosion
Time Evolution of Spectrum
Recession of photosphere reveals deeper layers
Fe
56Ni
Si/S/Ca
C/ODay 15 after explosion
ModelSN1994D
Width-Luminosity Relationship
Kasen and Woosley, ApJ, 2007 Vary 56Ni productionMNi = 0.35 to 0.70 Msun
The Width-Luminosity Relationship
Kasen and Woosley, ApJ, 2007
Vary 56Ni production
Brighter models are hotter andmore ionized and have different opacity behavior
The Width-Luminosity Relationship
Kasen and Woosley, ApJ, 2007
Vary 56Ni production
Vary silicon production(explosion energy)
Multi-Dimensional Models
Roepke et al (2005)
2D Deflagration Model
MNi = 0.2 Msun
EK = 0.3 x 1051 ergs
Roepke, Kasen, Woosley
DeflagrationToDetonationKhokhlov (1991)Hoeflich (1994)Gamezo et al (2005)
But how to detonate?
Gamezo et al.
2D Delayed Detonation
MNi = 0.5 Msun
EK = 1.2 x 1051 ergs
Roepke, Kasen, Woosley
Earlier Detonation (higher densities)gives more 56Ni production
Off-Center Ignition
University of Chicago FLASH Center
Detonation From Failed Deflagration Plewa, ApJ (2007)
Is the transition robust in3-dimensional calculations?
Off-center ExplosionPlewa (2007) Kasen and Plewa (2007)
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Asymmetry and SN Ia Diversity
Maximum Light Spectrum
Asymmetry and SN Ia Diversity
B-band Light Curve and the Phillips Relation
How and where does ignition happen?
How might the deflagration transition into a detonation?
Can we reproduce the observed spectra and light curves from first principles?
How do the light curves depend upon progenitor environment?
Pressing Questions
The Theoretical Understanding of Type Ia Supernovae