Type Ia Type Ia Supernovae:Supernovae:

standard standard candles?candles? Roger ChevalierRoger Chevalier

Supernovae – spectroscopic Supernovae – spectroscopic classificationclassification

Type I – H Type I – H absentabsent

Type II – H Type II – H presentpresent

Filippenko 97

Light curvesLight curves

Filippenko 97

Late spectraLate spectra

Filippenko 97

Why SN Ia for Why SN Ia for cosmology?cosmology?

LuminousLuminous Can occur in older stellar Can occur in older stellar

population; not closely tied to star population; not closely tied to star forming regionsforming regions

Uniform in propertiesUniform in properties

e.g., Colgate 79

Basic interpretation (c. Basic interpretation (c. 1980)1980)

Thermonuclear explosion of Thermonuclear explosion of Chandrasekhar mass (1.4 MChandrasekhar mass (1.4 M) white dwarf) white dwarf

Not a complete detonationNot a complete detonation No compact remnantNo compact remnant The white dwarf accretes in a binary The white dwarf accretes in a binary

systemsystem The burning produces ~0.6 MThe burning produces ~0.6 M of of 5656Ni, the Ni, the

decay of which powers the light curvedecay of which powers the light curve

Nuclear fusion gives ~10Nuclear fusion gives ~105151 ergs ergs Adiabatic expansion in going from 10Adiabatic expansion in going from 1099 cm to cm to

10101515 cm cm Power for radiation (~10Power for radiation (~104949 ergs) provided by ergs) provided by

radioactivityradioactivity

dayeFeCo

dayeCoNi

e

e

78

1.6

2/15626

5627

2/15627

5628

=+++→

=+++→+

+

τγν

τγν

Chevalier 81

Chevalier 81

Woosley & Weaver 86

Late Late spectruspectru

mm

Phillip’s Phillip’s relation relation (1993)(1993)

Hamuy et al. 96

Filippenko 97

Application of Application of the Phillip’s the Phillip’s relationrelation

Hamuy et al. 96

Light Light Curve Curve Shape Shape

methodmethod

Reiss, Press, Kirshner 96

SCP (Supernova Cosmology Project)SCP (Supernova Cosmology Project) S. Perlmutter et al.S. Perlmutter et al. Used Phillip’s relation and light curve Used Phillip’s relation and light curve

“stretch”“stretch” HZT (Hi – z Supernova Search HZT (Hi – z Supernova Search

Team)Team) B. Schmidt et al.B. Schmidt et al. Used LCS methodUsed LCS method

Riess et al. Riess et al. 20042004

SN Ia SN Ia Discoveries at Discoveries at z>1 from the z>1 from the HSTHST

SpectraSpectra

SN typeSN type Redshift zRedshift z

Riess et al.

Riess et al.

Riess et al.

Riess et al.

Evolution leading to SN Evolution leading to SN IaIa

Single degenerate in binary (standard Single degenerate in binary (standard model)model) Low accretion of H – explodes and blown offLow accretion of H – explodes and blown off dM/dt>10dM/dt>10-7-7 M M/yr, stable accretion/yr, stable accretion dM/dt>3x10dM/dt>3x10-7-7 M M/yr, build up envelope /yr, build up envelope

→→ spiral-in? spiral-in? ““Hachisu” wind?Hachisu” wind?

Double degenerateDouble degenerate Gravitational radiation drives binary evolutionGravitational radiation drives binary evolution But, unstable mass transfer But, unstable mass transfer →→ burning to ONe burning to ONe

WD WD →→ accretion induced collapse accretion induced collapse

Explosion physicsExplosion physics 1-dimensional (spherical) models1-dimensional (spherical) models

DeflagrationDeflagration DD – delayed detonationDD – delayed detonation PDD – pulsating delayed detonationPDD – pulsating delayed detonation

3-dimensional models3-dimensional models Importance of Rayleigh-Taylor instabilityImportance of Rayleigh-Taylor instability

Ropke & Hillebrandt 05

Explaining the Phillips’ Explaining the Phillips’ relationrelation

Metallicity – more Metallicity – more CNO CNO →→ more more 2222Ne Ne →→ less less 5656NiNi

Central density at Central density at time of ignitiontime of ignition

Travaglio et al. 05

Conclusions Conclusions

We do not understand evolution We do not understand evolution leading to explosion, explosion leading to explosion, explosion mechanism, Phillips’ relation…mechanism, Phillips’ relation…

But, there are no indications that the But, there are no indications that the high-z SNe Ia are different from high-z SNe Ia are different from nearby onesnearby ones