1. Supernova Nucleosynthesis and Extremely Metal-Poor Stars
Nozomu Tominaga
(Univ. of Tokyo)
Collaborators: H.Umeda, K.Maeda, N.Iwamoto, K.Nomoto
OMEG07, 4-7 Dec. 2007, Hokkaido Univ.

2. Core-Collapse SNe C O Si Fe Massive Star (>10M8) He H Core collapse
e--capture SNe (8-10M8)
Temp [108K]
Burning Stage
Products
0.2 H He
1.5
C,O 7 C
Ne,Mg 15 Ne
O,Mg 30 O Si 40
Cr,Mn 50
NSE
56Ni H He C
Core collapse
Compact object
n emission
Energy deposition O Si Fe

3. CCSN Explosion Mechanism
Black hole-forming SNe
Accretion disk
Jet
Rapidly-rotating star
Core collapse
Accretion disk
Neutrino
Magnetic field
Jet formation
しかし、その爆発メカニズム、つまりどのようにして解放されたエネルギーを放出物質に伝えるかということは、いまだに明らかになっていません。中性子星、ブラックホールを形成するそれぞれの超新星において、核力、ニュートリノやニュートリノ、磁場・回転が重要だと考えられています。が、第一原理から行われている重力崩壊シミュレーションでは超新星の爆発に成功しないことが知られています。
Jet-induced explosion
35M8 star (MacFadyen et al. 99)

4. Explosive Nucleosynthesis
Post-shock Temperature
T∝R-3/4E1/4
Shock Propagation
T [109K] Fe
Complete Si burning
Fe,α,Ni,Zn,Co,V
Incomplete Si burning
Fe,Si,Cr,Mn
O burning Si 5 4
The elements synthesized not only in the evolution of stars but in the explosion of stars.
Explosive elements depend on temperatures.
Since the post-shock temperature is inversely proportional to the radius,
the explosive elements depend on positions like this figure.
After the explosion, In the inner region, the central remnant, a neutron star or a black hole is formed.
We call the boundary between the ejecta and the central remnant the mass cut.
The yield is the integration of the materials outside the masscut.
So, the yield of the SN depends on the mass cut. R
ejecta
NS/BH 3

5. Supernova-induced star formation
(e.g., Cioffi et al. 1988)
The metal-poor stars are formed
by the SN shock compression from
the mixture of
the materials ejected from SN
(Fe, C, O, etc.)
and
swept-up by shockwave
(H, He).
H, He
Fe, C, O, Mg, Si, Ca
The abundance patterns of EMP stars
reflect
nucleosynthesis in the parent star and SN.

6. Jet-induced explosion
Mms=40M8, Z=0
Edep=1.5x1052erg
BH/NS BH
cf. “Collapsar”(e.g., MacFadyen et al. 01)
Magnetorotational Supernovae
(e.g., Moiseenko et al. 06) .
With the code, we investigated hydrodynamics and nucleosynthesis in the jet-induced explosions. In our calculation, we assume the jet generation around a central remnant and injected the parameterized jet from the inner boundary. As the time proceeds, the materials of the horizontal region fallback onto the central region. And the jets propagate the stars. In this study, we investigate the dependence on the energy injection rate, E dot jet with applying other parameters same.
Edep[erg/s]:
Energy deposition rate
parameter
(NT et al. 07)

7. Dependence: energy deposition rates.
Edep↓: Infall↑ M(Fe)↓ [C/Fe]↑ . .
Edep=120x1051erg/s
Edep=1.5x1051erg/s H H He He
The energy deposition rate affects not only on the initiation of the jet injection but also on the lateral expansion of the jets and cocoon. The white regions show where the infallen materials locate in the progenitor star. The infall region is larger for the smaller energy deposition rate and the infall decreases the inner materials relative to the outer materials. Thus the ratios C/O, C/Mg, and C/Fe are larger for the smaller energy deposition rates.
O/C
O/C
Infall Si
O/Mg Fe
Infall

8. (tending to be lower [Fe/H])
Results: M(Fe) & [C/X]
Larger Edep .
Larger M(Fe)
Smaller M(Fe)
Explosive
Larger Edep .
Jet
HMP
EMP stars
CEMP stars
UMP stars
HMP stars
[C/Mg]
UMP
CEMP
It would be interesting to count the number of the observed GRBs and metal-poor stars, although the statistics is too poor. 5 nearby GRBs are observed so far, consisting of 3 GRB-HNe and 2 no-SN GRBs. On the other hand, 13 metal-poor stars with [Fe/H] smaller than -3.5 are observed so far, consisting of 7 EMP stars, 4 CEMP stars, and 2 HMP stars. The ratios are shown in the figure and both ratios are consistent. Further, the region of the models, that would be the ultra metal-poor stars, is narrow. It could be an origin of the metallicity desert.
[C/Fe]
EMP
Higher [C/Fe] for
smaller M(Fe)
(tending to be lower [Fe/H])
[C/O]

9. . . . Abundance patterns EMP stars CEMP stars HMP stars
Edep=30x1051erg/s
M(56Ni)~0.1M8 .
CEMP stars
Edep=3x1051erg/s
M(56Ni)~8x10-4M8 .
HMP stars
Edep= x1051erg/s
M(56Ni)~3-4x10-6M8 .

10. . . Summary-1 UMP EMP stars HMP SNe with various E and Mms CEMP
(NT, Umeda, Nomoto 07)
When Edep is large .
HMP
CEMP
EMP
EMP, CEMP, (UMP), HMP stars
Jet-induced SNe with various Edep .

11. A peculiar EMP stars: HE1424-0241
A peculiar Si-deficient star (Cohen et al. 07) Fe Si Mg He
Jet
R/1014 [cm]
[Mg/Si]~1.4
A possible explanation
Angular dependent yield
(NT 07 arXiv: )
Abundance mixing due to the ISM interaction??

12. . . Summary-1 UMP EMP stars HMP SNe with various E and Mms CEMP
(NT, Umeda, Nomoto 07)
When Edep is large .
HMP
CEMP
EMP
EMP, CEMP, (UMP), HMP stars
Jet-induced SNe with various Edep
Angular dependence?? .

13. Summary-2 Abundance patterns of the EMP stars
Jet-induced explosion of stars as massive as SNe in the present days (Mms <100M8)
Variations of the EMP stars
Variation of energy deposition rate
Higher [C/Fe] tends to be realized for lower [Fe/H].
Variation of progenitor mass and explosion energy
Angular dependence → Outliers of the EMP stars
According to the simulation of First Star formation
(e.g., Yoshida et al. 06)
First stars are more massive than 100M8
Second stars with 40M8 are formed from primordial gas?