Explosive Nucleosynthesis in Core Collapse Supernovae

1

EXPLOSIVE NUCLEOSYNTHESIS IN

CORE COLLAPSE SUPERNOVAEMarco Limongi

INAF - Osservatorio Astronomico di Roma, ITALY [email protected]

Alessandro ChieffiINAF - Istituto di Astrofisica Spaziale e Fisica

Cosmica, ITALY [email protected]

mailto:[email protected]

mailto:[email protected]

2PRE-SUPERNOVA STAGE

The Fe core is partially degenerate

The pressure due to degenerate electrons dominate

3THE PATH TO THE EXPLOSIONPhotodisintegrations and Electron Captures Highly degenerate zone exceeds the Chandrasekhar Mass from a fast contraction to a collapse Highly degenerate zone

Fe core

Limiting Mass

4THE PATH TO THE EXPLOSIONPhotodisintegrations and Electron Captures Highly degenerate zone exceeds the Chandrasekhar Mass from a fast contraction to a collapseCollpase proceeds to nuclear densities ( ) – EOS stiffens ( ) – The inner core becomes incompressible, decelerates and rebounds

Woosley & Janka 2008

5THE PATH TO THE EXPLOSIONPhotodisintegrations and Electron Captures Highly degenerate zone exceeds the Chandrasekhar Mass from a fast contraction to a collapseCollpase proceeds to nuclear densities ( ) – EOS stiffens ( ) – The inner core becomes incompressible, decelerates and reboundsPrompt shock wave forms and propagates through the outer core – During this propagation it dissociates Fe nuclei into free nucleons and loses

Woosley & Janka 2008

6THE PATH TO THE EXPLOSIONPhotodisintegrations and Electron Captures Highly degenerate zone exceeds the Chandrasekhar Mass from a fast contraction to a collapseCollpase proceeds to nuclear densities ( ) – EOS stiffens ( ) – The inner core becomes incompressible, decelerates and reboundsPrompt shock wave forms and propagates through the outer core – During this propagation it dissociates Fe nuclei into free nucleons and loses The shock consumes its entire kinetic energy still within the Fe core - It turns into an accretion shock at a radius between 100 and 200 km and the Explosion Fails

7THE PATH TO THE EXPLOSIONPhotodisintegrations and Electron Captures Highly degenerate zone exceeds the Chandrasekhar Mass from a fast contraction to a collapseCollpase proceeds to nuclear densities ( ) – EOS stiffens ( ) – The inner core becomes incompressible, decelerates and reboundsPrompt shock wave forms and propagates through the outer core – During this propagation it dissociates Fe nuclei into free nucleons and loses The shock consumes its entire kinetic energy still within the Fe core - It turns into an accretion shock at a radius between 100 and 200 km and the Explosion FailsLots of neutrinos are emitted from the newly forming neutron star at the center - The persistent neutrino energy deposition behind the shock keeps the pressure high in this region and drives the shock outwards again, eventually leading to a supernova explosion.

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The most recent and detailed simulations of core collapse SN explosions show that:

the shock still stalls No explosion is obtainedthe energy of the explosion is a factor of 3 to 10 lower than usually observedWork is underway by all the theoretical groups to better

understand the problem and we may expect progresses in the next future

The simulation of the explosion of the envelope is needed to have information on:

the chemical yields (propagation of the shock wave compression and heating explosive nucleosynthesis)the initial mass-remnant mass relation

THE CURRENT CCSN MODELSAfter two decades of research the paradigm of the neutrino driven wind explosion mechanism is widely accepted, but….

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Propagation of the shock wave through the

envelope

Compression and

HeatingExplosive

Nucleosynthesis

The explosive nucleosynthesis calculations for core collapse supernovae are still based on explosions induced by injecting an arbitrary amount of energy in a (also arbitrary) mass location of the presupernova model and then following the development of the blast wave by means of an hydro code.

• Piston

• Thermal Bomb

• Kinetic Bomb

EXPLOSIVE NUCLEOSYNTHESIS

10EXPLOSION AND FALLBACK

Matter Falling Back

Mass Cut

Initial Remnan

t

Final Remnant

Matter Ejected into the ISMEkin1051 erg

• Piston (Woosley & Weaver)• Thermal Bomb (Nomoto & Umeda)• Kinetic Bomb (Chieffi & Limongi)

Different ways of inducing the explosion

FB depends on the binding energy: the higher is the initial mass the higher is the binding energy

Fe core

Shock WaveCompression and Heating

Induced Expansion

and Explosion

Initial Remnan

t

Injected Energy

11BASIC PROPERTIES OF THE EXPLOSION• Behind the shock, the pressure is dominated by

radiation• The shock propagates adiabatically

rT1

Fe core

r2

T2

r1

Shock

The peak temperature does not depend on the stellar structure

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Since nuclear reactions are very temperature sensitive, this cause nucleosynthesis to occur within few seconds that might otherwise have taken days or years in the presupernova evolution.

CHARACTERISTIC EXPLOSIVE BURNING TEMPERATURES

Where in general:

The typical burning timescale for destruction of any given fuel is:

13CHARACTERISTIC EXPLOSIVE BURNING TEMPERATURES

These timescales for the fuels He, C, Ne, O, Si are determined by the major destruction reaction:

and in general are function of temperature and density:

He burning:

C burning:

Ne burning:

O burning:

Si burning:

14CHARACTERISTIC EXPLOSIVE BURNING TEMPERATURES

If we take typical explosive burning timescales of the order of 1s

Explosive C burningExplosive Ne burningExplosive O burningExplosive Si burning

Thielemann et al. 1998

15

5000

Explosive O burning

6400

Explosive Ne burning

11750

Explosive C burning

13400RADIUS (Km)

No M

odifi

catio

n

By combining the properties of the matter at high temperature and the basic properties of the explosion we

expect

Explosive Si burning

This is independent of the details of the progenitor star

16ROLE OF THE PROGENITOR STAR• Mass-Radius relation @ Presupernova

Stage:determines the amount of mass contained in each volume determines the amount of mass processed by each explosive burning.

Explosive O burning

Explosive Ne burning

Explosive C burning

No M

odifi

catio

nExplosive Si burning

INTERIOR MASS

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• The Ye profile at Presupernova Stage:it is one of the quantities that determines the chemical composition of the more internal zones that reach the NSE/QSE stage

ROLE OF THE PROGENITOR STAR• Mass-Radius relation @ Presupernova


Ye=0.50 56Ni=0.63 – 55Co=0.11 – 52Fe=0.07 – 57Ni=0.06 – 54Fe=0.05Ye=0.49 54Fe=0.28 – 56Ni=0.24 – 55Co=0.16 – 58Ni=0.11 – 57Ni=0.08

T=5∙109 K r=108 g/cm3

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• The Ye profile at Presupernova Stage:it is one of the quantities that determines the chemical composition of the more internal zones that reach the NSE/QSE stage

• The Chemical Composition at Presupernova Stage:it determines the final composition of all the more external regions undergoing explosive (in non NSE/QSE regine)/hydrostatic burnings

ROLE OF THE PROGENITOR STAR• Mass-Radius relation @ Presupernova


19THE HYDRODYNAMICSSets the details of the physical conditions (temporal evolution of Temperature and Density) for each explosive burning the detailed products of each explosive burning

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• For T>5 109 K all the forward and the reverse strong reactions (with few exceptions) come to an equilibrium and a NSE distribution is quickly established

COMPLETE EXPLOSIVE SI BURNING

In this condition the abundance of each nucleus is given by:

These equations have the properties of favouring the more bound nucleus corresponding to the actual neutrons excess.

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jlik rr

i + k j + l

),max()(

jlik

jlik

rr

rrij

0)( ij

No equilibrium1)( ij

Full equilibrium

Since the matter exposed to the explosion has Ye>0.49

(h<0.02)

Most abundant isotope 56Ni

Elements also produced: Ti (48Cr) , Co (59Ni), Ni (58Ni)

COMPLETE EXPLOSIVE SI BURNING

22INCOMPLETE EXPLOSIVE SI BURNING• Temperatures between 4 109 K < T < 5 109 K are not high enough to

allow a complete exhaustion of 28Si, although the matter quickly reaches a NSE distribution

Main products: Ti (48Cr), V (51Cr), Cr (52Fe), Mn (55Co)

23EXPLOSIVE O BURNING• Temperatures between 3.3 109 K < T < 4 109 K are not high

enough to allow a full NSE

• Two equilibrium clusters form separted at the level of the bottleneck @ A=44

• Since the matter exposed to the explosion has A<44 and since there is a very small leackage through the bottleneck @ A=44, the path to the heavier elements is severely inhibited

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• Temperatures between 3.3 109 K < T < 4 109 K are not high enough to allow a full NSE

• Two equilibrium clusters forms separted at the level of the bottleneck @ A=44

• Since the matter exposed to the explosion has A<44 and since there is a very small leackage through the bottleneck @ A=44, the path to the heavier elements is severely inhibited

Main products: Si (28Si), S (32S) , Ar (36Ar), Ca (40Ca)

EXPLOSIVE O BURNING

25EXPLOSIVE C/NE BURNING• If T < 3.3 109 K the processes are far from the

equilibrium and nuclear processing occur through a well defined sequence of nuclear reactions.

Elements preferrentially synthesized in these conditions over the typical eplosion timescales:

• If T < 1.9 109 K no nuclear processing occur over the typical explosion timescales.

Si (28Si), P (31P), Cl (35Cl), K (39K), Sc (45Sc)

26COMPOSITION OF THE EJECTAEXPLOSIVE BURNINGS

Limongi & Chieffi 2006

27Hydrostatic Production Explosive Production Core He burning C

ShellC/Ne O Si-i Si-c

Si (28Si) 50 50P (31P) 15 25 60

S (32S) 30 30 35

Cl (60% 35Cl - 40% 37Cl) 35Cl 37Cl 100

100

Ar (36Ar) 30 70

K (39K) 70 20

Ca (40Ca) 15 75

Sc (45Sc) 35 25 35

Ti (30% 46Ti - 60% 48Ti) 46Ti 48Ti (48Cr)

50 4060 40

V [51V (51Cr)] 20 60 10

Cr [52Cr (20% 52Mn - 80% 52Fe) 52Mn 52Fe

6565

3535

Mn [55Mn (20% 55Fe - 80% 55Co) 55Fe 55Co

60 2070

2030

Fe [56Fe (56Ni)] 10 90

Co [59Co (80% 59Co - 20% 59Ni) 59Co 59Ni

50 50100

Ni (80% 58Ni - 20% 60Ni) 58Ni 60Ni

100100

This

pict

ure

may

cha

nge

sligh

tly b

y ch

angi

ng th

e in

itial

mas

s and

/or

met

allic

ity


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During the propagation of the shock wave through the mantle some amount of matter may fall back onto the compact remnant

It depends on the binding energy of the star and on the final kinetic

energy

FALLBACK AND FINAL REMNANT

29

Sic

Sc,Ti,FeCo,Ni

56Ni

Sii

Cr,V,Mn

56Ni

Ox

Si,S,ArK,Ca

Fe Core

Initial Mass Cut

Sic

Sc,Ti,FeCo,Ni

56Ni

Sii

Cr,V,Mn

56Ni

Si,S,ArK,Ca

Fe Core

Ox

Initial Mass Cut

Sic

Sc,Ti,FeCo,Ni

56Ni

Sii

Si,S,ArK,Ca

56Ni

Cr,V,Mn

Ox

Sic

Sc,Ti,FeCo,Ni

56Ni

Sii

Cr,V,Mn

56Ni

Si,S,ArK,Ca

Ox

Final Mass Cut

THE EJECTION OF 56NI AND HEAVY ELEMENTS

The amount of 56Ni and heavy elements strongly depends on the Mass Cut

Remnant

30THE EJECTED 56NIIn absence of mixing a high kinetic energy is required to

eject even a small amount of 56Ni

31MIXING BEFORE FALLBACK MODEL

56Ni and heavy elements can be ejected even with extended fallback

Sic

Sc,Ti,FeCo,Ni

56Ni

Sii

Cr,V,Mn

56Ni

Ox

Si,S,ArK,Ca

Fe Core

Initial Mass Cut

Sic

Sc,Ti,FeCo,Ni

Sii

Cr,V,Mn

56Ni

Ox

Si,S,ArK,Ca

Mixing RegionFe Core

Initial Mass Cut

Sic

Sc,Ti,FeCo,Ni

Sii

Cr,V,Mn

56Ni

Ox

Si,S,ArK,Ca

Mixing Region

Final Mass Cut

Isotopes produced in

the innermost

zones

Remnant

56Ni 56Ni

56Ni

56Ni

56Ni

56Ni

56Ni

56NiUmeda & Nomoto 2003

32

No Mas

s Loss

Final Ma

ss

He-Cor

e Mass

He-CC

Mass

CO-Core Mass

Fe-Core Mass

WNL

WNE WC/WO

Remnan

t Mass

Neutron Star

Black Hole

SNII SNIb/c

Fallba

ck

RSG

Z=Z

E=1051 ergNL00 WIND

THE FINAL FATE OF A MASSIVE STAR


33THE YIELDS OF MASSIVE STARS


34THE YIELDS OF MASSIVE STARS


35CHEMICAL ENRICHMENT DUE TO A SINGLE MASSIVE STAR

The Production Factors (PFs) provide information on the global enrichment of the matter and its distribution

Solar MetallicityModels

36CHEMICAL ENRICHMENT DUE TO A GENERATION OF MASSIVE STARS

Yields averaged over a Salpeter IMF

The integration of the yields provided by each star over an initial mass function provide the chemical composition of the

ejecta due to a generation of massive stars

Production Factors averaged over a

Salpeter IMF

37CHEMICAL ENRICHMENT DUE TO A GENERATION OF MASSIVE STARS

Massive stars contribute significantly to the production of elements from C to Sr (~2 < PF( C < Z < Sr ) < ~11)Elements produced by explosive burnings are almost co-produced with O and also in roughly solar proportions except for the Fe peak elementsMassive stars contribute to the production of the Fe peak elements for about 30% of the global production.


38SUMMARY

Assuming a Salpeter IMF, massive stars contribute significantly to the production of elements from C to Sr (~2 < PF( C < Z < Sr ) < ~11)

Explosive nucleosynthesis (EN) occurs in the innermost zones (R<13500 km) of the exploding envelope (above the Fe core) of any massive starEN modifies significantly the presupernova abundances and is responsible for the production of all the elements from Si to Ni (with few exceptions)Because of the large binding energy, and hence large remnant masses, stars with M>30 M do not contribute to the enrichment of elements produced by EN

Elements produced by explosive burnings are almost co-produced with O and also in roughly solar proportions except for the Fe peak elementsMassive stars contribute to the production of the Fe peak elements for about 30% of the global production.

39MAIN UNCERTAINTIES IN THE EXPLOSIVE NUCLEOSYNTHESIS

All the uncertainties connected with the induced explosion model (how to kick the blast wave, where to inject the initial energy and in which form) How much energy required to infinity amount of fall back, freezoutTreatment of fallback (multidimensional calculations, jet induced explosions)Weak interactions working during the presupernova stages Ye profile chemical composition where NSE/QSE is reached during the explosion

Lack of selfconsistent model for core collapse explosion

4044TI NUCLEOSYNTHESIS

CasA as seen by IBIS/ISGRI onboard INTEGRALDistance 3 Kpc -- 335 yr old -- Mini 30 M Mend

16 M 3 lines : 67.9 KeV, 78.4 KeV, 1.157 MeVObserved: M(44Ti)=1.6 10-4 M

Predicted: M(44Ti)=3.0 10-5 M

Reanud et al. 2006

4144TI NUCLEOSYNTHESISNo production in normal freezout

4244TI NUCLEOSYNTHESISProduction in a-rich freezout

43THE ROLE OF THE MORE MASSIVE STARS

Large Fall Back

Mass Loss Prevents Destruction

Which is the contribution of stars with M ≥ 35 M?

They produce:~60% of the total C and N (mass loss)~40% of the total Sc and s-process elements (mass loss)No intermediate and iron peak elements (fallback)

44CHEMICAL ENRICHMENT DUE TO MASSIVE STARS

The average metallicity Z grows slowly and continuously with respect to the evolutionary timescales of the stars that contribute to the

environment enrichment

Most of the solar system distribution is the result (as a first approximation) of the ejecta of ‘‘quasi ’’–solar-

metallicity stars.

The PFs of the chemical composition provided by a generation of solar metallicity stars should be

almost flat

45CHEMICAL ENRICHMENT DUE TO MASSIVE STARS

Secondary Isotopes?

No room for other sources (AGB)

Remnant Masses? Type IaAGB?

n process. Other sources

uncertainExplosion?

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Explosive Nucleosynthesis in Core Collapse Supernovae