Type Ia Supernovae: standard candles?

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Type Ia Supernovaestandard candles?

• Roger Chevalier

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Supernovae spectroscopic classification

• Type I H absent
• Type II H present

Filippenko 97
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Light curves
Filippenko 97
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Late spectra
Filippenko 97
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Why SN Ia for cosmology?

• Luminous
• Can occur in older stellar population not
  closely tied to star forming regions
• Uniform in properties

e.g., Colgate 79
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Basic interpretation (c. 1980)

• Thermonuclear explosion of Chandrasekhar mass
  (1.4 M?) white dwarf
• Not a complete detonation
• No compact remnant
• The white dwarf accretes in a binary system
• The burning produces 0.6 M? of 56Ni, the decay
  of which powers the light curve

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• Nuclear fusion gives 1051 ergs
• Adiabatic expansion in going from 109 cm to 1015
  cm
• Power for radiation (1049 ergs) provided by
  radioactivity

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Chevalier 81
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Chevalier 81
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Woosley Weaver 86
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(No Transcript)
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Late spectrum
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Phillips relation (1993)
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Filippenko 97
Hamuy et al. 96
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• Application of the Phillips relation

Hamuy et al. 96
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Light Curve Shape method
Reiss, Press, Kirshner 96
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• SCP (Supernova Cosmology Project)
• S. Perlmutter et al.
• Used Phillips relation and light curve stretch
• HZT (Hi z Supernova Search Team)
• B. Schmidt et al.
• Used LCS method

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Riess et al. 2004

• SN Ia Discoveries at zgt1 from the HST

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Spectra

• SN type
• Redshift z

Riess et al.
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Riess et al.
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Riess et al.
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Riess et al.
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Evolution leading to SN Ia

• Single degenerate in binary (standard model)
• Low accretion of H explodes and blown off
• dM/dtgt10-7 M?/yr, stable accretion
• dM/dtgt3x10-7 M?/yr, build up envelope
  ? spiral-in?
• Hachisu wind?
• Double degenerate
• Gravitational radiation drives binary evolution
• But, unstable mass transfer ? burning to ONe WD
  ? accretion induced collapse

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Explosion physics

• 1-dimensional (spherical) models
• Deflagration
• DD delayed detonation
• PDD pulsating delayed detonation
• 3-dimensional models
• Importance of Rayleigh-Taylor instability

Ropke Hillebrandt 05
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Explaining the Phillips relation

• Metallicity more CNO ? more 22Ne
  ? less 56Ni
• Central density at time of ignition

Travaglio et al. 05
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Conclusions

• We do not understand evolution leading to
  explosion, explosion mechanism, Phillips
  relation
• But, there are no indications that the high-z SNe
  Ia are different from nearby ones