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

are needed to see this picture.

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)

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

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