LSU - 25 Oct 071 Supernovae of Type Ia Ronald F. Webbink Department of Astronomy University of Illinois SN 1994D in NGC 4526 (HST)

LSU - 25 Oct 072 Hachinger et al Supernova taxonomy

LSU - 25 Oct 073 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

LSU - 25 Oct 074 All SNe Ia are not the same

LSU - 25 Oct 075 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?

LSU - 25 Oct 076 What do we know? Occur in both spiral and elliptical galaxies Li 2007

LSU - 25 Oct 077 What do we know? Occur in both spiral and elliptical galaxies Rate in spirals correlates with star formation rate (prompt component) McMillan & Ciardullo 1996

LSU - 25 Oct 078 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

LSU - 25 Oct 079 What do we know? Speed correlates with galaxy type Gallagher et al. 2005

LSU - 25 Oct 0710 What do we know? Speed correlates with galaxy type No H, He => M CSM < ~0.03 M sun Lundqvist 2007

LSU - 25 Oct 0711 What do we know? Speed correlates with galaxy type No H, He => M CSM < ~0.03 M sun Radio- and X-ray non-detections => dM/dt < ~10 -7 M sun yr -1 Panagia, et al Hughes et al. 2007

LSU - 25 Oct 0712 What do we know about the progenitors? White dwarf progenitors No H, He Some SNe Ia from old stellar populations

LSU - 25 Oct 0713 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

LSU - 25 Oct 0714 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 56 Ni to 56 Co to 56 Fe decay Spectra Light curves Röpke et al. 2007

LSU - 25 Oct 0715 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 56 Ni to 56 Co to 56 Fe decay Spectra Light curves Binary systems No other plausible way to trigger instability

LSU - 25 Oct 0716 Common envelope evolution Yungelson 2007

LSU - 25 Oct 0717 Stable mass transfer Yungelson 2007

LSU - 25 Oct 0718 SN Ia Progenitors Yungelson 2007

LSU - 25 Oct 0719 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

LSU - 25 Oct 0720 Cataclysmic Variables Outbursting binaries: Classical Novae (CN) Dwarf novae (DN) Novalike variables (NL) Magnetic CVs (MCV) M wd ~ M sun M donor < ~2/3 – 1 M sun Accretion events (DN, NL, MCV) dM/dt ~ – M sun yr -1 P crit ~ dyne cm -2 => Thermonuclear runaway

LSU - 25 Oct 0721 Nova ignition masses Townsley & Bildsten 2005

LSU - 25 Oct 0722 Gehrz et al. 1998

LSU - 25 Oct 0723 Classical nova outbursts Runaways erode M wd ! Many classical novae contain ONeMg white dwarfs

LSU - 25 Oct 0724 Recurrent Novae M wd close to M Ch Ejecta lack the heavy-element enhancements characteristic of classical novae => dM wd /dt > 0 ? Core composition unknown, but likely to be ONeMg white dwarfs (cf. CN) Rare: Death rate ~ SN Ia rate

LSU - 25 Oct 0725 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 M wd mostly unknown, but those in T CrB, RS Oph (erstwhile RNe) must be near M Ch Extremely H-rich environment

LSU - 25 Oct 0726 Munari & Zwitter 2002

LSU - 25 Oct 0727 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

LSU - 25 Oct 0728 Supersoft X-ray Sources Heterogeneous class of objects (incl. PNNe, SNR, Symbiotic Stars), but many are stable H-burning white dwarfs Population synthesis predicts ~10 3 SSS in M31 if SN Ia progenitors

LSU - 25 Oct 0729 SSS in M31 centerdisk Di Stefano 2007

LSU - 25 Oct 0730 Supersoft X-ray Sources Heterogeneous class of objects (incl. PNNe, SNR, Symbiotic Stars), but many are stable H-burning white dwarfs Population synthesis predicts ~10 3 SSS in M31 if SN Ia progenitors => 10 2 times number seen in X-rays Can they be hidden?

LSU - 25 Oct 0731 Evolution of SSS Di Stefano & Nelson 1996

LSU - 25 Oct 0732 Supersoft X-ray Sources Can they be hidden? Perhaps super-Eddington luminosity (accretion + burning) drives a massive stellar wind Hachisu & Kato 2003

LSU - 25 Oct 0733 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

LSU - 25 Oct 0734 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

LSU - 25 Oct 0735 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 10 9 yr

LSU - 25 Oct 0736 Problems with Single-Degenerate Progenitors Instability of He-burning shell

LSU - 25 Oct 0737 Thermal pulses in AGB stars Iben & Renzini 1983

LSU - 25 Oct 0738 Thermal pulses in accreting white dwarfs Cassisi, Iben & Tornambè 1998

LSU - 25 Oct 0739 Problems with Single-Degenerate Progenitors Instability of He-burning shell –What of Surface Hydrogen Burning?

LSU - 25 Oct 0740 Surface Hydrogen Burning Starrfield 2007

LSU - 25 Oct 0741 Surface Hydrogen Burning

LSU - 25 Oct 0742 Problems with Single-Degenerate Progenitors Instability of He-burning shell Ablation of H-rich donor in supernova event

LSU - 25 Oct 0743 Marietta, Burrows & Fryxell 2000

LSU - 25 Oct 0744

LSU - 25 Oct 0745 Problems with Single-Degenerate Progenitors Instability of He-burning shell Ablation of H-rich donor in supernova event Surviving companion?

LSU - 25 Oct 0746 Companion peculiar velocities Canal, Méndez & Ruiz-Lapuente 2001

LSU - 25 Oct 0747 Tycho (SN1572) Companion? Ruiz-Lapuente, et al. 2004

LSU - 25 Oct 0748 Companion Rotation Velocities Schmidt 2007

LSU - 25 Oct 0749 Tycho G revisited Schmidt 2007

LSU - 25 Oct 0750 Edge-Lit Detonations Degenerate ignition of ~0.1 M sun of He on ~1 M sun 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 M donor < ~0.05 M sun 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

LSU - 25 Oct 0751 Failed Double Detonation Bildsten 2007

LSU - 25 Oct 0752 CO +CO White Dwarf Mergers Wide range of delay times from GR inspiral Yungelson 2007

LSU - 25 Oct 0753 CO +CO White Dwarf Mergers Wide range of delay times from GR inspiral Eddington-limited accretion ignites carbon at the base of the accreted envelope (1D) Nomoto & Iben 1985

LSU - 25 Oct 0754 CO +CO White Dwarf Mergers Wide range of delay times from GR inspiral Eddington-limited accretion ignites carbon at the base of the accreted envelope (1D) But mass transfer occurs on a dynamical time scale

LSU - 25 Oct 0755 White dwarf coalescence Yoon, Podsiadlowski & Rosswog 2007

LSU - 25 Oct 0756 Merged Double White Dwarf Yoon, Podsiadlowski & Rosswog 2007

LSU - 25 Oct 0757 CO +CO White Dwarf Mergers Wide range of delay times from GR inspiral Eddington-limited accretion ignites carbon at the base of the accreted envelope (1D) But mass transfer occurs on a dynamical time scale Carbon ignition quenched in 2D or 3D by meridional expansion

LSU - 25 Oct 0758 Problems with Double-Degenerate Progenitors Tidal synchronization and preheating during approach to merger Iben, Tutukov & Fedorova 1998

LSU - 25 Oct 0759 Problems with Double-Degenerate Progenitors Tidal synchronization and preheating during approach to merger Angular momentum transport

LSU - 25 Oct 0760 Synchronization at low accretion rates KH – Kelvin-Helmholtz instability BC – Baroclinic instability TS – Tayler-Spruit dynamo Piro 2007

LSU - 25 Oct 0761 Problems with Double-Degenerate Progenitors Tidal synchronization and preheating during approach to merger Angular momentum transport Shock heating of accreted matter and the site of carbon ignition => Neutrino cooling of accreted envelope?

LSU - 25 Oct 0762 Are there enough double-degenerates? Napiwotzki 2007

LSU - 25 Oct 0763 Theoretical DD Search Yields

LSU - 25 Oct 0764 SN Ia Progenitor Comparative Yields Yungelson 2007

LSU - 25 Oct 0765 The Parting Shot: We’re looking for haystacks, not needles! Maoz 2007