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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