大質量星の超新星爆発:
ガンマ線バーストと金属欠乏星

冨永 望(東京大学)
Submitted to ApJ Letter

Collaborators:
前田啓一, 梅田秀之,野本憲一, 田中雅臣(東大),岩本信之(JAEA),
P. A. Mazzali(MPA)Gamma-ray bursts (GRBs)

Discovered in 1970’s.
Gamma-ray (~100keV)
is emitted instantly.

Long GRBs with HNez 3 long GRBs are associated with HNe.
 GRB 980425/SN 1998bw (z=0.0085, Nakamura et al. 2001)
 GRB 030329/SN 2003dh (z=0.1687, Mazzali et al. 2003)
 GRB 031203/SN 2003lw (z=0.1055, Mazzali et al. 2006)[Cf., GRB 060218/SN 2006aj (z=0.0335, Mazzali et al. 2006) is a X-ray Flash (XRF).]HNe are very energetic explosion
massivestars.
(>1052erg)Γ~of100
Γ~ 10The luminosities are very high.
M(56Ni)~0.3M

GRB 060505 & GRB 060614
Della Valle et al. 2006, Gal-Yam et al. 2006,Fynbo et al. 2006, Gehrels et al. 2006

GRB 060505 at z=0.089

GRB 060614 at z=0.125

The associated SNe have not been detected andthe upper limits to SNe are ~1/100 of SN1998bw.

M(56Ni)<10-3M
http://swift.gsfc.nasa.gov/

Why the SNe were not detected?

Chance superposition?
Schaefer & Xiao 2006, Cobb et al. 2006

z~0.1-0.2
Cobb et al. 2006

but....
Gehrels et al. 2006

GRB060505
GRB060614

Possibilities: chance superposition0.5”

Della Valle et al. 2006

z Galaxy counts Æ 1%

Cobb et al. 2006z HST image Æ x 0.2%

2x10-5 : Gehrels et al. 2006

AV ~ 0.1

AV ~ 0.5

0.01x0.002 = 1/(2x105)GRBs
Gal-Yam et al. 2006 (HST)~200 GRBs are detected by Swift.

Short GRBs with long tails?
tlag

GRB060614: Gehrels et al. 2006
Long GRBs

The isotropic γ-ray energy of GRB060614 is~1051erg, being larger than typical short GRBs.
Can the long tail be reproduced by thecompact star merger model? SN GRBs
Short GRBs

Long GRBs with Faint SNe?
z Faint SNe are Type II SNe.
(Detected by bright plateau.) SN 1994W (Sollerman et al. 1998)
M(56Ni)<2.6 x 10-3M
 SN 1997D (Turrato et al. 1998)
10-3M <M(56Ni)<10-2M

The explosion energies are small (E<1051 ergs).
Can small M(56Ni) be compatible withthe formation of energetic GRBs?

Jet-induced explosion
JetJetBH/NS

BH

cf. Collapsar model(MacFadyen, Woosley, & Heger 2001)

.

Edep:
Energy deposition rate
(Rotation etc.)
Same mass and explosion energy
40M

15x1051erg

Relativistic jets
inducedNucleosynthesisJet parameters.E , Γ , E , f
dep

θjet

Mremjetdep.E :
dep

Energy deposition ratethProgenitor: Z=0, MMS=40M
Total deposited enegy:
Edep=1.5x1052erg
Initial remnant mass:
Mrem=1.4M
Initial opening angle: θjet=15o
Initial velocity: Γjet=100
Ratio of thermal to total
deposited energies:
fth=Eth/ Edep=10-3

Energy deposition rate [1051 erg s-1]

Initiation of the jet injection
C+O layer: shallow ρ(r)1

101010-2

In order to initiate
the jet injection,

Pjet>Pfall

3x1051erg/s
Freefall-1

10ρ, vfall

Pjet

1020

Pfall

.

Spherical infall
calculation

Edep(Pjet=Pfall)

Pfall ∝ ρ vfall2 ∝ ρ02 r09/2

Fryer & Meszaros 2003
2 4 6 8 10 12 14 16 18 20 Maeda & NT 2007
Infalled
mass [M]Mass
NT et al. 2007

Sites of 56Ni production
z Explosive nucleosynthesis(e.g. Maeda & Nomoto 2003)z Jet

Mjet~Edep /c2/Γmax~10-4M
(Edep =1.5x1052ergs, Γmax=100)

Shock
BH

.

.

Dependence:
Edep E ↓: Infall↑.
depM(56Ni)↓.

Larger Edep.

Smaller Edep

He layerO/C layer
O/Mg layer

SiFe

InfallInfallEjected 56Ni masses
100

Explosive

Ejected 56Ni masses [M]

10-1

10

GRB-HN
Sub-luminous SN-2

10

10-4

10-5

Faint SN.

-3

The explosions with small Edep yieldsmall M(56Ni),
Jet even if the explosions
accompany relativistic jets.
GRB060505
GRB060614

3x1051erg/s10-6110100

Energy deposition rates [1051 erg s-1]

1000Otherelements.

Smaller Edep
Smaller M(56Ni)
Larger [C/Fe]
Nucleosynthesis
in a single SN

Metal-poor stars

Metal-poor stars
These stars reflect nucleosynthesis in a single Pop III SN.

HMP
4UMP

Cayrel et al. 2004
Honda et al. 2004
HMP stars[C/Fe]

3[Fe/H]>-2.8

2

Hierarchical Chemical Evolution(Tumlinson 2006)
Integration of several SNe.

C-rich EMP

1EMP

0-1
-5-4-3
Metallicity [Fe/H]-2-10

CEMP stars(Depagne et al. 2002)

M(56Ni)~8x10-4MEMP stars(Cayrel et al. 2004)

M(56Ni)~0.2M

HMP stars(Christlieb et al. 2002)(Frebel et al. 2005)

M(56Ni)~3x10-6M

Counts

60%(3/5)
40%(2/5)

5 nearby GRBs
3 GRB-HNe
2 no-SN GRBs
(excluding XRF060218)

15%(2/13)
For [Fe/H]<-3.5
13 metal-poor stars
7 EMP stars
4 CEMP stars
2 HMP stars

25%(4/13)
60%(7/13)

BH-forming SNe with relativistic jets
GRBs

Metal-poor stars

GRB-HNeEMP stars

No-SN GRBs

CEMP stars
HMP stars

Larger.

Edep
Smaller

No-SN GRBs are also massive stellar deaths.
BH-forming SNe with relativistic jets are responsible
for GRBs-HNe and no-SN GRBs and metal-poor stars.