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Supernovae of Type Ia

Supernovae of Type Ia. Supernovae of Type Ia. Ronald F. Webbink Department of Astronomy University of Illinois. SN 1994D in NGC 4526 (HST). Supernova taxonomy. www.astronomy.com. Hachinger et al. 2006. Cosmological significance. SNe Ia as standard candles

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Supernovae of Type Ia

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  1. Supernovae of Type Ia Supernovae of Type Ia Ronald F. Webbink Department of Astronomy University of Illinois SN 1994D in NGC 4526 (HST)

  2. Supernova taxonomy www.astronomy.com Hachinger et al. 2006

  3. Cosmological significance • SNe Ia as standard candles • Magnitude => Expansion of light sphere with respect to comoving coordinates • Redshift => Expansion of comoving coordinates Wood-Vasey, et al. 2007

  4. All SNe Ia are not the same www.nd.edu/~kkrisciu

  5. What is the physical cause of this dispersion? • Is it truly independent of redshift? • What secondary factors should affect SN Ia properties? => Physics of supernova explosions • What are their progenitors? www.nd.edu/~kkrisciu

  6. What do we know? • Occur in both spiral and elliptical galaxies Li 2007

  7. What do we know? • Occur in both spiral and elliptical galaxies • Rate in spirals correlates with star formation rate (prompt component) McMillan & Ciardullo 1996

  8. What do we know? • Occur in both spiral and elliptical galaxies • Rate in spirals correlates with star formation rate (prompt component) • Persistent rate among passive (elliptical) galaxies (delayed component) Sullivan et al. 2006

  9. What do we know? • Speed correlates with galaxy type Gallagher et al. 2005

  10. What do we know? • Speed correlates with galaxy type • No H, He => MCSM < ~0.03 Msun Lundqvist 2007

  11. What do we know? • Speed correlates with galaxy type • No H, He => MCSM < ~0.03 Msun • Radio- and X-ray non-detections => dM/dt < ~10-7 Msun yr-1 Panagia, et al. 2006 Hughes et al. 2007

  12. What do we know about the progenitors? • White dwarf progenitors No H, He Some SNe Ia from old stellar populations

  13. What do we know about the progenitors? • White dwarf progenitors No H, He Some SNe Ia from old stellar populations • Thermonuclear runaway Spectra No compact remnants found Stehle, et al. 2005

  14. What do we know about the progenitors? • White dwarf progenitors No H, He Some SNe Ia from old stellar populations • Thermonuclear runaway Spectra No compact remnants found • Powered by 56Ni to 56Co to 56Fe decay Spectra Light curves Röpke et al. 2007

  15. What do we know about the progenitors? • White dwarf progenitors No H, He Some SNe Ia from old stellar populations • Thermonuclear runaway Spectra No compact remnants found • Powered by 56Ni to 56Co to 56Fe decay Spectra Light curves • Binary systems No other plausible way to trigger instability

  16. Common envelope evolution Yungelson 2007

  17. Stable mass transfer Yungelson 2007

  18. SN Ia Progenitors Yungelson 2007

  19. Candidate Progenitors • Single Degenerates Cataclysmic Variables Recurrent Novae Symbiotic Stars Supersoft X-ray Sources • Edge-Lit Detonations sdHe/HeWD + CO WD • Double Degenerates CO + CO White Dwarfs

  20. Outbursting binaries: Classical Novae (CN) Dwarf novae (DN) Novalike variables (NL) Magnetic CVs (MCV) Mwd ~ 0.6-1.0 Msun Mdonor < ~2/3 – 1 Msun Accretion events (DN, NL, MCV) dM/dt ~ 10-11 – 10-8 Msun yr-1 Pcrit ~ 1019 dyne cm-2 => Thermonuclear runaway Cataclysmic Variables

  21. Nova ignition masses Townsley & Bildsten 2005

  22. Gehrz et al. 1998

  23. Classical nova outbursts • Runaways erode Mwd! • Many classical novae contain ONeMg white dwarfs

  24. Recurrent Novae • Mwd close to MCh • Ejecta lack the heavy-element enhancements characteristic of classical novae => dMwd/dt > 0 ? • Core composition unknown, but likely to be ONeMg white dwarfs (cf. CN) • Rare: Death rate ~ 10-2 SN Ia rate

  25. Symbiotic Stars • Heterogenous class of objects, mostly wind-accreting WD companions to luminous M giants or AGB stars • Hot components mostly powered by H burning on white dwarf • Mwd mostly unknown, but those in T CrB, RS Oph (erstwhile RNe) must be near MCh • Extremely H-rich environment

  26. Munari & Zwitter 2002

  27. Supersoft X-ray Sources • Heterogeneous class of objects (incl. PNNe, SNR, Symbiotic Stars), but many are stable H-burning white dwarfs Nomoto et al. 2007

  28. Supersoft X-ray Sources • Heterogeneous class of objects (incl. PNNe, SNR, Symbiotic Stars), but many are stable H-burning white dwarfs • Population synthesis predicts ~103 SSS in M31 if SN Ia progenitors

  29. SSS in M31 center disk Di Stefano 2007

  30. Supersoft X-ray Sources • Heterogeneous class of objects (incl. PNNe, SNR, Symbiotic Stars), but many are stable H-burning white dwarfs • Population synthesis predicts ~103 SSS in M31 if SN Ia progenitors => 102 times number seen in X-rays • Can they be hidden?

  31. Evolution of SSS Di Stefano & Nelson 1996

  32. Supersoft X-ray Sources • Can they be hidden? • Perhaps super-Eddington luminosity (accretion + burning) drives a massive stellar wind Hachisu & Kato 2003

  33. Supersoft X-ray Sources • Can they be hidden? • Perhaps super-Eddington luminosity (accretion + burning) drives a massive stellar wind • BUT such a model predicts • H, He-rich ejecta • Relatively dense stellar wind both in violation of observational limits

  34. Supersoft X-ray Sources • Can they be hidden? • Perhaps super-Eddington luminosity (accretion + burning) drives a massive stellar wind • BUT such a model predicts • H, He-rich ejecta • Relatively dense stellar wind both in violation of observational limits • Alternative: Super-Eddington accretion regenerates AGB giant

  35. Supersoft X-ray Sources • Can they be hidden? • Perhaps super-Eddington luminosity (accretion + burning) drives a massive stellar wind • BUT such a model predicts • H, He-rich ejecta • Relatively dense stellar wind both in violation of observational limits • Alternative: Super-Eddington accretion regenerates AGB giant • Maximum lifetime to carbon ignition (delay to SN Ia) ~ 1.6 X 109 yr

  36. Problems withSingle-Degenerate Progenitors • Instability of He-burning shell

  37. Thermal pulses in AGB stars Iben & Renzini 1983

  38. Thermal pulses in accreting white dwarfs Cassisi, Iben & Tornambè 1998

  39. Problems withSingle-Degenerate Progenitors • Instability of He-burning shell • What of Surface Hydrogen Burning?

  40. Surface Hydrogen Burning Starrfield 2007

  41. Surface Hydrogen Burning

  42. Problems withSingle-Degenerate Progenitors • Instability of He-burning shell • Ablation of H-rich donor in supernova event

  43. Marietta, Burrows & Fryxell 2000

  44. Problems withSingle-Degenerate Progenitors • Instability of He-burning shell • Ablation of H-rich donor in supernova event • Surviving companion?

  45. Companion peculiar velocities Canal, Méndez & Ruiz-Lapuente 2001

  46. Tycho (SN1572) Companion? Ruiz-Lapuente, et al. 2004

  47. Companion Rotation Velocities Schmidt 2007

  48. Tycho G revisited Schmidt 2007

  49. Edge-Lit Detonations • Degenerate ignition of ~0.1 Msun of He on ~1 Msun CO white dwarf can trigger double detonation • Mass transfer too rapid from non-degenerate He star donor to permit accreted envelope to cool to degeneracy and develop strong flashes • Degenerate donors have even higher mass transfer rates until Mdonor < ~0.05 Msun • Degenerate He ignition produces outward-propagating detonation, but fails to detonate CO core, or to produce intermediate-mass elements (e.g., Si) seen at maximum light

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