Explosive Nucleosynthesis in Core Collapse Supernovae

1. Explosive Nucleosynthesis in Core Collapse Supernovae Marco Limongi INAF - Osservatorio Astronomico di Roma, ITALY marco.limongi@oa-roma.inaf.it Alessandro Chieffi INAF - Istituto di AstrofisicaSpazialeeFisicaCosmica, ITALY alessandro.chieffi@iasf-roma.inaf.it

2. Pre-SuperNova Stage The pressure due to degenerate electrons dominate The Fe core is partially degenerate

3. The Pathto the Explosion • Photodisintegrations and Electron Captures  Highly degenerate zone exceeds the Chandrasekhar Mass  from a fast contraction to a collapse Highly degenerate zone Fe core Limiting Mass

4. The Pathto the Explosion • Photodisintegrations and Electron Captures  Highly degenerate zone exceeds the Chandrasekhar Mass  from a fast contraction to a collapse • Collpaseproceedstonucleardensities ( ) – EOS stiffens ( ) – The innercorebecomesincompressible, decelerates and rebounds Woosley & Janka 2008

5. The Pathto the Explosion • Photodisintegrations and Electron Captures  Highly degenerate zone exceeds the Chandrasekhar Mass  from a fast contraction to a collapse • Collpaseproceedstonucleardensities ( ) – EOS stiffens ( ) – The innercorebecomesincompressible, decelerates and rebounds Prompt shock wave forms and propagates through the outer core – During this propagation it dissociates Fe nuclei into free nucleons and loses Woosley & Janka 2008

6. The Pathto the Explosion • Photodisintegrations and Electron Captures  Highly degenerate zone exceeds the Chandrasekhar Mass  from a fast contraction to a collapse • Collpaseproceedstonucleardensities ( ) – EOS stiffens ( ) – The innercorebecomesincompressible, decelerates and rebounds Prompt 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

7. The Pathto the Explosion • Photodisintegrations and Electron Captures  Highly degenerate zone exceeds the Chandrasekhar Mass  from a fast contraction to a collapse • Collpaseproceedstonucleardensities ( ) – EOS stiffens ( ) – The innercorebecomesincompressible, decelerates and rebounds Prompt 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 Lots 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.

8. The Current CCSN Models After two decades of research the paradigm of the neutrino driven wind explosion mechanism is widely accepted, but…. The mostrecent and detailedsimulationsofcorecollapse SN explosions show that: • the shock still stalls  No explosion is obtained • the energyof the explosionis a factorof3to 10 lowerthanusuallyobserved Work isunderwaybyall the theoreticalgroupstobetterunderstand the problem and wemayexpectprogresses in the next future The simulationof the explosionof the envelopeisneededtohave information on: • the chemical yields (propagation of the shock wave  compression and heating explosive nucleosynthesis) • the initialmass-remnant mass relation

9. ExplosiveNucleosynthesis Propagationof the shock wavethrough the envelope Compression and Heating ExplosiveNucleosynthesis 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 presupernovamodeland thenfollowing the development of the blast wavebymeansofanhydro code. • Piston • Thermal Bomb • Kinetic Bomb

10. Explosion and Fallback Matter Falling Back Matter Ejected into the ISM Ekin1051 erg Shock Wave Compression and Heating Induced Expansion and Explosion Mass Cut Final Remnant Initial Remnant Initial Remnant Injected Energy Fe core • Piston (Woosley & Weaver) • ThermalBomb (Nomoto & Umeda) • KineticBomb (Chieffi & Limongi) Differentwaysofinducing the explosion FB depends on the bindingenergy: the higheris the initial mass the higheris the bindingenergy

11. BasicPropertiesof the Explosion • Behind the shock, the pressureisdominatedbyradiation • The shock propagates adiabatically Shock Fe core T1 T2 r1 r r2 The peak temperature doesnotdepend on the stellar structure

12. CharacteristicExplosiveBurningTemperatures Sincenuclearreactions are very temperature sensitive, this cause nucleosynthesistooccurwithinfewsecondsthatmightotherwisehavetakendays or years in the presupernovaevolution. The typicalburningtimescalefordestructionofanygivenfuelis: Where in general:

13. CharacteristicExplosiveBurningTemperatures Thesetimescalesfor the fuelsHe, C, Ne, O, Si are determinedby the major destructionreaction: Heburning: Cburning: Ne burning: O burning: Si burning: and in general are functionof temperature and density:

14. CharacteristicExplosiveBurningTemperatures Ifwe take typicalexplosiveburningtimescalesof the orderof 1s Thielemann et al. 1998 Explosive C burning Explosive Ne burning Explosive O burning Explosive Si burning

15. Bycombining the propertiesof the matter at high temperature and the basicpropertiesof the explosionweexpect Explosive O burning Explosive Ne burning Explosive C burning Explosive Si burning No Modification 5000 6400 11750 13400 RADIUS (Km) Thisisindependentof the detailsof the progenitor star

16. Roleof 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 Explosive Si burning No Modification INTERIOR MASS

17. Roleof 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. • The Yeprofile at Presupernova Stage: itisoneof the quantitiesthatdeterminesthe chemicalcompositionof the more internalzonesthatreach the NSE/QSE stage r=108g/cm3 T=5∙109 K Ye=0.50  56Ni=0.63 – 55Co=0.11 – 52Fe=0.07 – 57Ni=0.06 – 54Fe=0.05 Ye=0.49  54Fe=0.28 – 56Ni=0.24 – 55Co=0.16 – 58Ni=0.11 – 57Ni=0.08

18. Roleof 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. • The Yeprofile at Presupernova Stage: itisoneof the quantitiesthatdeterminesthe chemicalcompositionof the more internalzonesthatreach the NSE/QSE stage • The ChemicalComposition at Presupernova Stage: itdetermines the finalcompositionofall the more externalregionsundergoingexplosive (in non NSE/QSE regine)/hydrostaticburnings

19. The Hydrodynamics Sets the details of the physical conditions (temporal evolution of Temperature and Density) for each explosive burning  the detailed products of each explosive burning

20. Complete Explosive Si Burning • ForT>5109 Kall the forward and the reverse strong reactions (withfewexceptions) come toanequilibrium and a NSE distributionisquicklyestablished In thiscondition the abundanceofeachnucleusisgivenby: Theseequationshave the propertiesoffavouring the more boundnucleuscorrespondingto the actualneutronsexcess.

21. Complete Explosive Si Burning j + l i + k Since the matterexposedto the explosionhasYe>0.49 (h<0.02) Mostabundant isotope 56Ni No equilibrium Full equilibrium Elementsalsoproduced: Ti (48Cr) , Co (59Ni), Ni (58Ni)

22. Incomplete Explosive Si Burning • Temperaturesbetween4 109 K < T < 5 109 K are not high enoughtoallow a complete exhaustionof28Si, although the matterquicklyreaches a NSE distribution Mainproducts: Ti (48Cr), V (51Cr), Cr (52Fe), Mn (55Co)

23. Explosive O Burning • Temperaturesbetween3.3 109 K < T < 4 109 K are not high enoughtoallow a full NSE • Twoequilibriumclustersformseparted at the levelof the bottleneck @ A=44 • Since the matterexposedto the explosionhas A<44 and sincethereis a verysmallleackagethrough the bottleneck @ A=44, the pathto the heavierelementsisseverelyinhibited

24. Explosive O Burning • Temperaturesbetween3.3 109 K < T < 4 109 K are not high enoughtoallow a full NSE • Twoequilibriumclustersformsseparted at the levelof the bottleneck @ A=44 • Since the matterexposedto the explosionhas A<44 and sincethereis a verysmallleackagethrough the bottleneck @ A=44, the pathto the heavierelementsisseverelyinhibited Mainproducts: Si (28Si), S (32S) , Ar (36Ar), Ca (40Ca)

25. ExplosiveC/Ne burning • IfT < 3.3 109K the processes are far from the equilibrium and nuclear processing occurthrough a welldefinedsequenceofnuclearreactions. Elements preferrentially synthesized in these conditions over the typical eplosion timescales: Si (28Si), P (31P), Cl (35Cl), K (39K), Sc (45Sc) • IfT< 1.9 109K no nuclear processing occurover the typicalexplosiontimescales.

26. Compositionof the Ejecta EXPLOSIVE BURNINGS Limongi & Chieffi 2006

27. This picture may change slightly by changing the initial mass and/or metallicity Limongi & Chieffi 2006

28. Fallback And FinalRemnant During the propagationof the shock wavethrough the mantle some amountofmattermayfall back onto the compact remnant Itdepends on the bindingenergyof the star and on the finalkineticenergy

29. TheEjectionof56Ni and HeavyElements Ox Ox Ox Ox Sii Sii Sii Sii 56Ni 56Ni 56Ni 56Ni Sic Sic Sic Sic 56Ni 56Ni 56Ni 56Ni Fe Core Fe Core Sc,Ti,Fe Co,Ni Sc,Ti,Fe Co,Ni Sc,Ti,Fe Co,Ni Sc,Ti,Fe Co,Ni Cr,V,Mn Cr,V,Mn Cr,V,Mn Cr,V,Mn Final Mass Cut Initial Mass Cut Initial Mass Cut Si,S,Ar K,Ca Si,S,Ar K,Ca Si,S,Ar K,Ca Si,S,Ar K,Ca Remnant The amountof56Ni and heavyelementsstronglydepends on the Mass Cut

30. TheEjected56Ni In absenceof mixing a high kineticenergyisrequiredtoejecteven a smallamountof56Ni

31. Mixing Before Fallback Model 56Ni Isotopes produced in the innermost zones Ox Ox Ox 56Ni 56Ni Sii Sii Sii Sic Sic 56Ni Sic Mixing Region 56Ni 56Ni 56Ni Fe Core Fe Core 56Ni Mixing Region Remnant 56Ni Sc,Ti,Fe Co,Ni Sc,Ti,Fe Co,Ni Sc,Ti,Fe Co,Ni Cr,V,Mn Cr,V,Mn Cr,V,Mn 56Ni Initial Mass Cut Initial Mass Cut Final Mass Cut 56Ni Si,S,Ar K,Ca Si,S,Ar K,Ca 56Ni Si,S,Ar K,Ca Umeda & Nomoto 2003 56Ni and heavyelements can beejectedevenwithextendedfallback

32. Z=Z E=1051 erg NL00 No Mass Loss WIND SNII SNIb/c RSG WNL Final Mass WC/WO WNE He-Core Mass Fallback Remnant Mass He-CC Mass CO-Core Mass Black Hole Fe-Core Mass Neutron Star The Final Fate Of A Massive Star Limongi & Chieffi 2007

33. The Yieldsof Massive Stars Limongi & Chieffi 2006

34. The Yieldsof Massive Stars Limongi & Chieffi 2006

35. ChemicalEnrichment due to a Single Massive Star The Production Factors (PFs) provide information on the global enrichmentof the matter and itsdistribution SolarMetallicity Models

36. ChemicalEnrichment dueto a Generation of Massive Stars The integrationof the yieldsprovidedbyeach star overaninitial mass functionprovide the chemicalcompositionof the ejecta due to a generation of massive stars Yieldsaveragedover a Salpeter IMF Production Factorsaveragedover a Salpeter IMF

37. ChemicalEnrichment dueto a Generation of Massive Stars Limongi & Chieffi 2007 Massive starscontributesignificantlyto the production ofelementsfromCto Sr (~2 < PF( C < Z < Sr ) < ~11) Elementsproducedbyexplosiveburnings are almostco-producedwith O and also in roughlysolarproportionsexceptfor the Fe peakelements Massive starscontributeto the production of the Fe peakelementsforabout 30% of the global production.

38. Summary Explosivenucleosynthesis (EN) occurs in the innermostzones (R<13500 km) of the explodingenvelope (above the Fe core) ofany massive star EN modifiessignificantly the presupernovaabundances and isresponsiblefor the production ofall the elementsfrom Si to Ni (withfewexceptions) 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 Assuming a Salpeter IMF, massive starscontributesignificantlyto the production ofelementsfromCto Sr (~2 < PF( C < Z < Sr ) < ~11) Elementsproducedbyexplosiveburnings are almostco-producedwith O and also in roughlysolarproportionsexceptfor the Fe peakelements Massive starscontributeto the production of the Fe peakelementsforabout 30% of the global production.

39. MainUncertainties in the ExplosiveNucleosynthesis Lackofselfconsistentmodelforcorecollapseexplosion All the uncertaintiesconnectedwith the inducedexplosionmodel (howtokick the blastwave, wheretoinject the initialenergy and in whichform) Howmuchenergyrequiredtoinfinity amount of fall back, freezout Treatment 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

40. 44Ti Nucleosynthesis CasAasseenby IBIS/ISGRI onboard INTEGRAL Distance 3 Kpc -- 335 yr old -- Mini 30 M Mend 16 M 3 lines : 67.9 KeV, 78.4 KeV, 1.157 MeV Observed: M(44Ti)=1.6 10-4 M Predicted: M(44Ti)=3.0 10-5 M Reanud et al. 2006

41. 44Ti Nucleosynthesis No production in normalfreezout

42. 44Ti Nucleosynthesis Production in a-richfreezout

43. The Roleof the More Massive Stars Which is the contribution of stars with M ≥ 35 M? Mass Loss Prevents Destruction Large Fall Back 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)

44. Chemical 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

45. ChemicalEnrichment due to Massive Stars No roomforothersources (AGB) RemnantMasses? Secondary Isotopes? AGB? Type Ia n process. Other sources uncertain Explosion?

46. THE END