Nuclear matter in neutron stars

1
Nuclear matter in neutron stars investigated by
experiments and astronomical observations ???????
????????????
A research project applying a Grant-in-Aid to
create a new science area (15M USD) ????????
(15??) ???
H. Tamura Department of Physics, Tohoku Unviersity
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1. Motivation
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World of matter made of u, d, s quarks
Stable
Higher density
How well can we understand neutron stars from
strangeness nuclear physics?
3-dimensional nuclear chart

by M. Kaneta inspired by HYP06 conference poster
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Maximum mass of n stars and hyperon mixing
(1.97??0.04)M?,
(1.97??0.04)
NNNNN
NNNNN
NNNNN YN YY
NNNNN YN YY
central density
Radius
Z.H. Li and H.-J. Schulze, PRC78(2008) 028801
n-star mass seems to be explained by hyperon
mixing.(but slightly too light)
1.44M
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Heavy neutron star?
Shapiro delay
Heavy neutron star?

• Nature 467 (2010) 1081
• J1614-2230
• (1.97??0.04)Msun

To obtain robust error estimates, we used a
Markov chain Monte Carlo (MCMC) approach to
explore the post-fit ? space and derive posterior
probability distributions for all timing model
parameters
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Hyperon mixing in neutron stars
Hyperon (and kaon) fractions are sensitive
to hyperon (kaon) potentials (YN, YY, KbarN
interactions)
USlt0 U?lt0
We need XN force (both I 1 and 0), LL
force SN force (I 3/2 (S-n) is particularly
important) KbarN force (both I1 and 0)
LN-SN and LNN force, LN p-wave force,
USgt0 U?lt0
Fraction
USgt0 U?gt0
????
r/r0
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EOS constraints from astronomical observations
Thermonuclear Burst in X-ray Binaries 4U
1608-248 EXO 1745-248 4U 1820-30
Probability of EOS P(e)
Ozel et al., arXiv 1002.3153 astro-ph.HE
A. W. Steiner, et al., arXiv1005.0811
Better understanding of nuclear matter in nuclear
physics More and reliable data for radius from X
ray observations
gt EOS can be determined.
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2. Our Project
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r
EOS coveringwide range of r, p/n asymmetry,
strangeness
World-best two acceleratorsandastronomical
satellite
D theory
neutron star
C astronomical X-ray observation
?radius and mass
? asymmetric nuclear matter and thin
neutron matter
A strangeness nuclear physics
? Interactions between strange particles
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Neutron star matter and our research subjects
Ohnishi (YITP)
fm-3
Takahashi (KEK)
Tamura (Tohoku)
Murakami (Kyoto)
n, p, L, X,.. ?
n
nuclei n
Nakamura (TIT)
Baryon density
Fraction
Takahashi (JAXA)
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????

• X00 ??????????????????? ?? ??(???)
• Nuclear matter in neutron stars investigated
  by H. Tamura (Tohoku)
• experiments and astronomical observations
• A01 ????????????????? ?? ??(???)
• Strangeness in neutron-rich nuclear matter
  H. Tamura (Tohoku)
• A02 ???????????????????
  ????(KEK)
• Multi-strangeness baron-baryon
  interactions T. Takahashi (KEK)
• B01 ???????????????
  ????(???)
• Properties of low/medium density
  neutron-rich T. Nakamura (TIT)
• nuclear matter
• B02 ????????????????? ????(??)
• EOS of high-density neutron-rich nuclear
  matter T. Murakami (Kyoto)

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A01 Strangeness in neutron-rich matter Sp,
S-p scattering exp. Miwa, -gt SN
interactions(in particular, Sp S-n
interaction) Spectroscopy of n-rich L
hypernuclei (E10) Sakaguchi,... g-spectroscopy
of hypernuclei (E13) Tamura, Koike,.. -gt LN,
LN-SN (LNN) interaction in n-rich matterK-
nuclear bound states (E15) Outa, Iwasaki,.. -gt
KbarN interactionA02 Multi-strangeness
baryon-baryon interactions X hypernuclear
spectroscopy (E05) Nagae, X atomic X-rays
(E03) Tanida, LL hypernuclei and X atomic
X-rays (E07) Nakazawa, S -2 resonance
Sato, Imai,... -gt LL, XN, XN-SN
interactions, H dibaryon-like state
A Strange nuclear matter
at J-PARC
Tamura (Tohoku)
??????
T. Takahashi (KEK)
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B EOS of neutron-rich matter
at RIBF
Nakamura (TIT)
Murakami (Kyoto)
Horikoshi (Tokyo)
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C X-ray observations
T. Takahashi (JAXA)

• Observables for radius

• kHz QPO (quasi periodic oscillation)
• Periodic X ray burst from a nuclear fusion
  spot orbiting near the surface of the n star

Several data samples exist.

• Red shift (30) of absorption lines from the
  surface of the n star

Only a few data samples exist.

• ASTRO-H 2014
• 10 good samples of kHz QPO and red shift
  for radius expected.
• Better X-ray detectors should be developed for
  future

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Present constraints to mass-radius relation
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D01 Theory group (slide by Ohnishi)
???????? ?? ?(?????)????????????? ?????
????(???)??????????????? ?? ?(?????)???????????
?? ?(???)n-rich ???????? ?? ?(???) ???????? ?
??(??) ?????????????? ?? ?(???)
????????????????? ????(KEK) K????????????? ????(?
?) ????????????? ????? ??(??)???(???)???(?????)?
??(?)(JAEA)????(?????)???(???)???(???)
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D01 Theory group (slide by Ohnishi)

• ???????????????(?????????(??(?)??)?...)
• ???????????????????? Abe, Seki, 2009
• ???????????????BEC-BCS cross over
• ????????????????????
• ????????????? (?????????...)
• r0 ???????????0? ????????????????
• ?????????(M3Y)????HF
• GMR?????????????????

• ?????????(????????????...)
• ?????-????? ? ???S???(Hypernuclear Sym. E. ?)
• ???????????(K, p, ..)
• M1.67 Msun ????3??
• ??????(????????????...)
• ?????????( p ??)????
• ????????????? ? Quarkyonic??????????

• X??????????????? (???????????...)
• TOV????????M(R) versus P(e) ?1?1??
• ?????????? ???????( Baym et al., Lattimer et
  al.)
• ???????????????????????????????!(????)
• ??????(?????????....)
• ???????????????????????

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How to use money shared use
A01 Detector system for YN scattering exp.
(fiber trackers) Development of
high-rate beam line trackers Fast
readout system for Hyperball-J A02 Emulsion,
emulsion scanning system DSSD for LL
nuclei and X X-rays Decay particle
detector (TPC) for S-2 resonance
B01 A new generation neutron counters gt A01
kaonic nucleus, g-ray calorimeter
(LaBr crystal array etc.) gt A01 hypernuclear g
rays Laser cooling system for cold
atoms B02 TPC in SAMURAI CsI forward
calorimeter C01 Development of new X/g-ray
detectors (Compton camera w/ Ge, CdTe,
Si..) gt can be tested in
J-PARC/RIBF D01 PDs Workshops
NEBULA (NEutron Detection System for Breakup of
Unstable Nuclei with Large Acceptance)
SAMURAI
RIBF SAMURAI n-coutners, g detectors, TPC
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3. Summary

• Combined with nuclear physics experiments and
  astronomical observations, nuclear matter EOS in
  neutron stars will be able to be determined.

• The proposed project combines researches on
  A Strangeness nuclear physics experiments at
  J-PARC B Neutron-rich nuclear experiments
  at RIBF Ultra-cold Fermi atoms by
  laser cooling C X-ray observations by
  ASTRO-H satellite D Theoretical studies
  in order to determine THE EOS covering wide
  ranges of density, asymmetry, and including
  strangeness.

• We are applying a grant (15M USD for 5 years in
  total) to MEXT.