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Type Ia Supernovae: standard candles?

Type Ia Supernovae: standard candles?. Roger Chevalier. Type I – H absent Type II – H present. Supernovae – spectroscopic classification. Filippenko 97. Light curves. Filippenko 97. Late spectra. Filippenko 97. Why SN Ia for cosmology?. Luminous

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Type Ia Supernovae: standard candles?

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  1. Type Ia Supernovae:standard candles? Roger Chevalier

  2. Type I – H absent Type II – H present Supernovae – spectroscopic classification Filippenko 97

  3. Light curves Filippenko 97

  4. Late spectra Filippenko 97

  5. 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

  6. 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

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

  8. Chevalier 81

  9. Chevalier 81

  10. Woosley & Weaver 86

  11. Late spectrum

  12. Phillip’s relation (1993)

  13. Filippenko 97 Hamuy et al. 96

  14. Application of the Phillip’s relation Hamuy et al. 96

  15. Light Curve Shape method Reiss, Press, Kirshner 96

  16. SCP (Supernova Cosmology Project) • S. Perlmutter et al. • Used Phillip’s relation and light curve “stretch” • HZT (Hi – z Supernova Search Team) • B. Schmidt et al. • Used LCS method

  17. SN Ia Discoveries at z>1 from the HST Riess et al. 2004

  18. Spectra • SN type • Redshift z Riess et al.

  19. Riess et al.

  20. Riess et al.

  21. Riess et al.

  22. Evolution leading to SN Ia • Single degenerate in binary (standard model) • Low accretion of H – explodes and blown off • dM/dt>10-7 M/yr, stable accretion • dM/dt>3x10-7 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

  23. 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

  24. Explaining the Phillips’ relation • Metallicity – more CNO → more 22Ne → less 56Ni • Central density at time of ignition Travaglio et al. 05

  25. 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

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