Quark deconfinement in compact stars

1
Quark deconfinement in compact stars
connection with GRBs
Irene Parenti
Univ. of Ferrara Italy
INFN of Ferrara Italy
International summer school Hot points in
Astrophysics and Cosmology
Dubna, Russia 2 13 August 2004
August 2004
Irene Parenti
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Summary

• Short overview on Gamma-Ray Bursts
• (GRBs)

• Delayed nucleation of Quark Matter

• Implication for the mass and radius of
• compact stars

• How to generate Gamma-Ray Bursts
• from deconfinement

• Conclusions

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Gamma-Ray Bursts (GRBs)
Spatial distribution isotropic
Distance cosmological (1-10)109 ly
Energy range 100 KeV a few MeV
Emitted energy 1051 erg (beamed/jets)
Duration (0,01-300) s
J.S. Bloom, D.A. Frail, S.R. Kulkarni, ApJ 594,
2003
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GRB and supernovae
Connection between GRB and Supernovae
Evidence for atomic lines in the spectra of the
X-ray afterglow
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Time delay from SN to GRB
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A two-stages scenario
1st explosion SUPERNOVA (birth of a NS)
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Delayed collapse of a HS to a QS
Z. Berezhiani, I. Bombaci, A. Drago, F. Frontera
and A. Lavagno ApJ. 586 (2003) 1250
Possible central engine for GRB

• The conversion process can be delayed due to the
  effects
• of the surface tension between the HM phase and
  the QM
• phase.
• The nucleation time depends drammatically on the
  central
• pressure of the HS.
• As a critical-size drop of QM is formed the HS is
  
• converted to a QS or a HyS.
• The conversion process releases Econv. 1052 -
  1053 erg

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The Quark-Deconfinement Nova model
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Finite-size effects

• The formation of a critical-size drop of QM is
• not immediate.
• Its necessary to have an overpressure to form a
• droplet having a size large enough to overcome
  the
• effect of the surface tension.

• A virtual droplet moves back and forth in the
• potential energy well on a time scale
• ?0-110-23 s tweak

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Quark deconfinement
virtual droplet of deconfined quark matter
hadronic matter in a metastable state
real droplet of deconfined quark matter
real droplet of strange matter
stable phase
This form of deconfined matter has the same
flavor content of the ß-stable hadronic system
at the same pressure. We call it Q-phase.
The drop grows with no limitation.
when p overcomes the transition point
in a time t
Soon afterwards the weak interactions change the
quark flavor fraction to lower the energy.
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Equation of State
Hadronic phase Relativistic Mean Field Theory
of hadrons interacting via meson exch. e.g.
Glendenning, Moszkowsky, PRL 67(1991)
Quark phase EOS based on the MIT bag model for
hadrons. Farhi, Jaffe, Phys. Rev. D46(1992)
Mixed phase Gibbs construction for a
multicom- ponent system with two conserved
charges. Glendenning, Phys. Rev. D46 (1992)
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Hybrid star mass-radius
B136,36 MeV/fm3
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Hybrid Star configuration
B136,36 MeV/fm3
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Strange Star mass-radius
B74,16 MeV/fm3
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Strange Star configuration
B74,16 MeV/fm3
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Quantum nucleation theory
I.M. Lifshitz and Y. Kagan, Sov. Phys. JETP 35
(1972) 206 K. Iida and K. Sato, Phys. Rev. C58
(1998) 2538
nQ baryonic number density in the Q-phase
at a fixed pressure P. µQ,µH chemical
potentials at a fixed pressure P. s
surface tension (10,30 MeV/fm2)
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Matter in the droplet
Flavor fractions are the same of the
ß-stable hadronic system at the same pressure
The pressure needed for phase transition is much
larger than that without flavor conservation.
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Nucleation time
The nucleation time is the time needed to form a
critical droplet of deconfined quark matter. It
can be calculated for different values of the
stellar central pressure (and then of the
stellar mass, as implied by TOV).
The nucleation time dramatically depends on the
value of the stellar central pressure and then
on the value of the stellar mass.
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The critical mass of metastable HS
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Two families of compact stars
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Mass-Radius constraints

• X-ray burster EXO 0748-676
• Cottam et al., Nature 420, 2002
• z0.35

• X-ray pulsar 1E 1207.4-5209
• Sanwal et al. ApJ 574, 2002, L61
• z0.12-0.23

• X-ray binary 4U 1728-34
• Li et al. ApJ 527,1999,L51
• Very compact object

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Mass-Radius constraints
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Energy released
The total energy released in the stellar
conversion is given by the difference between the
gravitational mass of the initial hadronic star
(MinMcr) and the mass of the final hybrid or
strange stellar configuration (MfinMQS(Mbcr))
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How to generate GRBs
The energy released is carried out by pairs of
neutrinos antineutrinos.
The reaction that generate gamma-ray is The
efficence of this reaction in a strong
gravitational field is J. D. Salmonson and
J. R. Wilson, ApJ 545 (1999) 859
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Conclusions

• Neutron stars (HS) are metastable to
• HS ?gt QS or to HS ?gt HyS

• Our model explains the connection and the
• time delay between SN and GRBs.

• possible existence of two different
• families of compact stars
• pure Hadronic Stars
• Hybrid stars or Strange Stars

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Collaborators

• Dr. Ignazio Bombaci
• Dr. Isaac Vidaña

Univ. of Pisa
INFN of Pisa
Ref I. Bombaci, I. P., I. Vidaña
arXivastro-ph/0402404 Astroph. J., accepted
Other collaborators

• Dr. Alessandro Drago
• Dr. Giuseppe Pagliara

Univ. of Ferrara
INFN of Ferrara
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Appendix
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Compact stars

• HADRONIC
• STARS
• (HS)
• HYBRID STARS
• (HyS)
• STRANGE STARS
• (SS or QS)

conventional neutron stars hyperon stars
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Probability of tunneling
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