supernovae of type ia

LSU - 25 Oct 07 1

Supernovae of Type Ia

Supernovae of Type Ia

Ronald F. Webbink

Department of Astronomy

University of Illinois

SN 1994D in NGC 4526 (HST)

LSU - 25 Oct 07 2Hachinger et al. 2006

Supernova taxonomy

www.astronomy.com

LSU - 25 Oct 07 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

LSU - 25 Oct 07 4

All SNe Ia are

not the same

www.nd.edu/~kkrisciu

LSU - 25 Oct 07 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

LSU - 25 Oct 07 6

What do we know?

• Occur in both spiral and elliptical galaxies

Li 2007

LSU - 25 Oct 07 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

LSU - 25 Oct 07 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

LSU - 25 Oct 07 9

What do we know?

• Speed correlates with galaxy type

Gallagher et al. 2005

LSU - 25 Oct 07 10

What do we know?

• Speed correlates with galaxy type

• No H, He => MCSM < ~0.03 Msun

Lundqvist 2007

LSU - 25 Oct 07 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

LSU - 25 Oct 07 12

What do we know about the progenitors?• White dwarf progenitors

No H, He

Some SNe Ia from old stellar populations

LSU - 25 Oct 07 13

What do we know about the progenitors?• White dwarf progenitors

No H, He

Some SNe Ia from old stellar

populations

• Thermonuclear runawaySpectra

No compact remnants found

Stehle, et al. 2005

LSU - 25 Oct 07 14

What do we know about the progenitors?• White dwarf progenitors

No H, He

Some SNe Ia from old stellar

populations

• Thermonuclear runawaySpectra

No compact remnants found

• Powered by 56Ni to 56Co

to 56Fe decaySpectra

Light curves Röpke et al. 2007

LSU - 25 Oct 07 15

What do we know about the progenitors?• White dwarf progenitors

No H, He

Some SNe Ia from old stellar populations

• Thermonuclear runawaySpectra

No compact remnants found

• Powered by 56Ni to 56Co to 56Fe decaySpectra

Light curves

• Binary systemsNo other plausible way to trigger instability

LSU - 25 Oct 07 16

Common envelope evolution

Yungelson 2007

LSU - 25 Oct 07 17

Stable mass transfer

Yungelson 2007

LSU - 25 Oct 07 18

SN Ia Progenitors

Yungelson 2007

LSU - 25 Oct 07 19

Candidate Progenitors• Single Degenerates

Cataclysmic VariablesRecurrent NovaeSymbiotic StarsSupersoft X-ray Sources

• Edge-Lit DetonationssdHe/HeWD + CO WD

• Double DegeneratesCO + CO White Dwarfs

LSU - 25 Oct 07 20

Cataclysmic Variables

• 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

LSU - 25 Oct 07 21

Nova ignition masses

Townsley & Bildsten 2005

LSU - 25 Oct 07 22

Gehrz et al. 1998

LSU - 25 Oct 07 23

Classical nova outbursts

• Runaways erode Mwd!

• Many classical novae contain ONeMg white dwarfs

LSU - 25 Oct 07 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

LSU - 25 Oct 07 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

LSU - 25 Oct 07 26Munari & Zwitter 2002

LSU - 25 Oct 07 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

LSU - 25 Oct 07 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

LSU - 25 Oct 07 29

SSS in M31

center disk

Di Stefano 2007

LSU - 25 Oct 07 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?

LSU - 25 Oct 07 31

Evolution of SSS

Di Stefano & Nelson 1996

LSU - 25 Oct 07 32

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 07 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

LSU - 25 Oct 07 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

LSU - 25 Oct 07 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

LSU - 25 Oct 07 36

Problems withSingle-Degenerate Progenitors

• Instability of He-burning shell

LSU - 25 Oct 07 37

Thermal pulses in AGB stars

Iben & Renzini 1983

LSU - 25 Oct 07 38

Thermal pulses in accreting white dwarfs

Cassisi, Iben & Tornambè 1998

LSU - 25 Oct 07 39

Problems withSingle-Degenerate Progenitors

• Instability of He-burning shell– What of Surface Hydrogen Burning?

LSU - 25 Oct 07 40

Surface Hydrogen Burning

Starrfield 2007

LSU - 25 Oct 07 41

Surface Hydrogen Burning

LSU - 25 Oct 07 42

Problems withSingle-Degenerate Progenitors

• Instability of He-burning shell• Ablation of H-rich donor in supernova event

LSU - 25 Oct 07 43

Marietta, Burrows & Fryxell 2000

LSU - 25 Oct 07 44

LSU - 25 Oct 07 45

Problems withSingle-Degenerate Progenitors

• Instability of He-burning shell• Ablation of H-rich donor in supernova event• Surviving companion?

LSU - 25 Oct 07 46

Companion peculiar velocities

Canal, Méndez & Ruiz-Lapuente 2001

LSU - 25 Oct 07 47

Tycho (SN1572) Companion?

Ruiz-Lapuente, et al. 2004

LSU - 25 Oct 07 48

Companion Rotation Velocities

Schmidt 2007

LSU - 25 Oct 07 49

Tycho G revisited

Schmidt 2007

LSU - 25 Oct 07 50

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

LSU - 25 Oct 07 51

Failed Double Detonation

Bildsten 2007

LSU - 25 Oct 07 52

CO +CO White Dwarf Mergers

• Wide range of delay times from GR inspiral

Yungelson 2007

LSU - 25 Oct 07 53

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 07 54

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 07 55

White dwarf coalescence

Yoon, Podsiadlowski & Rosswog 2007

LSU - 25 Oct 07 56

Merged Double White Dwarf

Yoon, Podsiadlowski & Rosswog 2007

LSU - 25 Oct 07 57

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 07 58

Problems withDouble-Degenerate Progenitors

• Tidal synchronization and preheating during approach to merger

Iben, Tutukov & Fedorova 1998

LSU - 25 Oct 07 59

Problems withDouble-Degenerate Progenitors

• Tidal synchronization and preheating during approach to merger

• Angular momentum transport

LSU - 25 Oct 07 60

Synchronization at low accretion rates

• KH – Kelvin-Helmholtz instability

• BC – Baroclinic instability

• TS – Tayler-Spruit dynamo

Piro 2007

LSU - 25 Oct 07 61

Problems withDouble-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 07 62

Are there enough double-degenerates?

Napiwotzki 2007

LSU - 25 Oct 07 63

Theoretical DD Search Yields

LSU - 25 Oct 07 64

SN Ia ProgenitorComparative Yields

Yungelson 2007

LSU - 25 Oct 07 65

The Parting Shot:We’re looking for haystacks, not needles!

Maoz 2007