Transcript Document

Stellar core collapse with
QCD phase transition
Ken’ichiro Nakazato
（Tokyo University of Science）
with K. Sumiyoshi（Numazu CT）and S. Yamada（Waseda U）,
EOS project: T. Miyatsu （Soongsil U）and S. Yamamuro（TUS）
Compact Stars in the QCD Phase Diagram IV @ Prerow, Sep. 27, 2014
Fates of massive stars
• Stars with > 10Msolar make a gravitational collapse and, possibly, a supernova explosion.
• Stars with > 25Msolar are thought to form a
black hole （BH）.
• Observations show
2 branches.
– Hypernovae
（Rapid rotation）
– Faint or Failed
Supernovae
（Weak rotation）
Normal
SN
Nomoto+ （2006）
Failed supernova neutrinos
• Failed supernova progenitor makes bounce
once and recollapse to the black hole.
• In this process, temperature and density of
central region gets a few times 10 MeV and
a few times r 0 (saturation density of nuclear
matter), and a lot of neutrinos are emitted.
Proto-neutron star
Massive star
n
Core
Collapse
Bounce
n
n
n
n
Mass accretion
Black hole
Motivation
• Collapsing core would be enough hot and
dense to undergo QCD transition.
~150MeV
Early
Universe
T
heavy ion
collision
Hadronic
Phase
Quark Phase
Mixed Phase
Black Hole
Formation
Supernova
0
r0
Compact stars
r
Aims of this study
Nakazato, Sumiyoshi and Yamada（2008a, 2010b, 2013b）.
• We compute the dynamics and n emission
for the black hole formation of 40Msolar
（failed supernova） and supernova explosion
of 15Msolar non-rotating progenitor involving
equation of state （EOS） with QCD transition.
– General relativistic n radiation hydrodynamics in
spherical symmetry （Sumiyoshi+ 2005）.
– QCD transition: Shen EOS + MIT bag
• We investigate the impacts on the dynamics
and n signal.
Hydrodynamics & Neutrinos
Yamada, Astrophys. J. 475 （1997）, 720
Yamada et al., Astron. Astrophys. 344 （1999）, 533
Sumiyoshi et al., Astrophys. J. 629 （2005）, 922
Spherical, Fully GR Hydrodynamics
metric：Misner-Sharp （1964）
mesh：255 non uniform zones
+
Neutrino Transport （Boltzmann eq.）
Species : ne ,ne , nm （ = nt ） ,nm （ =nt ）
Energy mesh : 14 zones （0.9 – 350 MeV）
Reactions : e- + p ↔ n + ne, e+ + n ↔ p +ne, n + N ↔ n + N,
n + e ↔ n + e, ne + A ↔ A’ + e-, n + A ↔ n + A,
e- + e+ ↔ n +n, g* ↔ n +n, N + N’ ↔ N + N’ + n +n
Hadron-quark mixed EOS
Nakazato et al., PRD 77 （2008a）, 103006
• Shen EOS （1998） for Hadronic phase
• MIT Bag model （Chodos et al. 1974） for Quark phase
– Bag constant: B = 90, 150 and 250 MeV/fm3
• Gibbs conditions are satisfied in Mixed phase.
– mn = mu + 2md ,
– PH = PQ

mp = 2mu + md
b equilibrium （n trapping） is assumed in Mixed
and Quark phase.
– md = ms ,
mp + me = mn + mn
Results for 40M☉ star
• Evolution of the
central density.
• QCD transition
fastens the BH
formation.
• At the bounce,
the case with
B = 90 MeV/fm3
has high density
while others are
similar.
B = 90 MeV/fm3
B = 150 MeV/fm3
B = 250 MeV/fm3
Without Quarks （Shen）
Compositions （B = 250 MeV/fm3）
Nakazato et al., Astrophys. J. 721 （2010b）, 1284
density （g/cm3） fraction
27 ms before
BH formation
1
0.07 ms before
BH formation
d
s
n
0.5
at BH formation
u
1
0.5
p
0
0
1015
1015
AH
1013
0
10
radius （km）
20 0
10
radius （km）
20 0
10
radius （km）
1013
20
• Quark transition occurs at the very late phase
and trigger the black hole formation.
Compositions （B = 90 MeV/fm3）
density （g/cm3） fraction
Nakazato et al., Astron. Astrophys. 558 （2013b）, A50
100 ms after
at bounce
at BH formation
bounce
1
u
n
0.5
s
1
d
0.5
p
0
0
1015
1015
AH
1013
0
10
radius （km）
20 0
10
radius （km）
20 0
1013
10
radius （km）
• Quarks appear already at bounce.
→ the central density gets higher.
20
energy（MeV） luminosity（1053erg/s）
Neutrino Signal
ne
2
90
150
nm /nm / nt /nt
ne
250
90
150
250
2
90
1
150
250
1
0
0
40
40
20
20
0
0
0
0.5
1
time （s）
1.5 0
1
0.5
time （s）
1.5 0
1
0.5
time （s）
1.5
• Apart from end points, there is no difference
even for the model with B = 90 MeV/fm3.
• Neutrinos emitted from the outer region.
Fate of 15M☉ star
• For the cases with B = 250,150 MeV/fm3 ,
QCD transition does not occur at least 1 sec
after the bounce.
mass trajectory
→ no SN explosion
Quark
Hadron
Mix
103
radius （km）
Phase diagram: B = 250 MeV/fm3
Yℓ = 0.3
Central r and T of 1 s after bounce
100
10
0
0.2 0.4 0.6 0.8 1
time after bounce （s）
（Sumiyoshi et al. 2005）
nd
2
bounce with B = 90 MeV/fm3
• Confirming 2nd bounce and shock formation
occurs for 15M☉ model. （Sagert+ 2009, Fischer+ 2011）
s = 4.0kB
Yℓ = 0.35
Mix → Quark
200.5 ms
Hadron → Mix
Our recent work
and ADVERTISEMENT
Japanese proverb
• 木に竹を接ぐ（Ki ni také wo tsugu）
– Joining bamboo to a tree: disharmony
tree
bamboo
New EOS for neutron star matter
Miyatsu, Yamamuro & Nakazato, ApJ 777 （2013）, 4
• Chiral quark-meson coupling （CQMC） model
– involving the coupling of scalar and vector fields
to the quarks within nucleons
• Relativistic Hartree-Fock
i
j
j
i
i
j
i
j
PI: Dr. Tsuyoshi Miyatsu
New EOS for neutron star matter
Miyatsu, Yamamuro & Nakazato, ApJ 777 （2013）, 4
• Crust EOS with Thomas-Fermi model
– consistent with atomic mass data
New EOS for neutron star matter
Miyatsu, Yamamuro & Nakazato, ApJ 777 （2013）, 4
• Mmax = 1.95Msolar with hyperons
New EOS for neutron star matter
Miyatsu, Yamamuro & Nakazato, ApJ 777 （2013）, 4
• http://asphwww.ph.noda.tus.ac.jp/myn/
Thank you for your attention
Chiral quark-meson coupling model
• 一様核物質の状態方程式
： Chiral quark-meson coupling model から
s dependence を取り込む（非線形効果）
– ベクトル中間子のテンソル結合により、ハイペロンの
生成が抑制される。
→ コア部分の状態方程式。
Coupling constant
• Thomas-Fermi 計算により、原子核の質量・核
子分布を計算し、N との結合定数を決める。
– gsN, gwN, grN : mass data
– gsY : Hyperon potential
（Oyamatsu & Iida 2003）
– gwY, grY, fwB, frB : ESC model を gwN, grN で scale
Thomas-Fermi 計算
• バルクエネルギーに一様核物質 EOS を用いる。
– Chiral quark-meson coupling model
n
陽子
幅 dr の領域
では一様
中性子
r
• 結合エネルギーを最大化
表面
エネルギー
クーロン
エネルギー
saturation パラメータ
n0 = 0.155 fm－3
w0 = -16.1 MeV
K0 = 274 MeV
Esym = 32.7 MeV
L = 75.8 MeV
Li et al.
arXiv:1211.1178
Esym (MeV)