1、,Quark deconfinement in compact stars:,Irene Parenti,Univ. of FerraraItaly,connection with GRBs,International summer school: “Hot points in Astrophysics and Cosmology”,Dubna, Russia 2 13 August 2004,August 2004,Irene Parenti,INFN of Ferrara Italy,Summary,Short overview on Gamma-Ray Bursts (GRBs),Del
2、ayed nucleation of Quark Matter,How to generate Gamma-Ray Bursts from deconfinement,Conclusions,August 2004,Irene Parenti,Implication for the mass and radius of compact stars,Gamma-Ray Bursts (GRBs),Spatial distribution: isotropic,Distance: cosmological (1-10)109 ly,Energy range: 100 KeV a few MeV,E
3、mitted energy: 1051 erg (beamed/jets),Duration: (0,01-300) s,J.S. Bloom, D.A. Frail, S.R. Kulkarni, ApJ 594, 2003,August 2004,Irene Parenti,GRB and supernovae,Connection between GRB and Supernovae,Evidence for atomic lines in the spectra of the X-ray afterglow,August 2004,Irene Parenti,Time delay fr
4、om SN to GRB,August 2004,Irene Parenti,A two-stages scenario,1st explosion:SUPERNOVA(birth of a NS),August 2004,Irene Parenti,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 centra
5、l 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,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 fo
6、r GRB,August 2004,Irene Parenti,The Quark-Deconfinement Nova model,August 2004,Irene Parenti,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 tens
7、ion.,A virtual droplet moves back and forth in the potential energy well on a time scale:0-110-23 s weak,August 2004,Irene Parenti,virtual droplet of deconfined quark matter,stable phase,when p overcomes the transition point,Quark deconfinement,hadronic matter in a metastable state,in a time ,real d
8、roplet of deconfined quark matter,This form of deconfined matter has the same flavor content of the -stable hadronic system at the same pressure. We call it: Q*-phase.,Soon afterwards the weak interactions change the quark flavor fraction to lower the energy.,The drop grows with no limitation.,real
9、droplet of strange matter,August 2004,Irene Parenti,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 pha
10、se: Gibbs construction for a multicom- ponent system with two conserved “charges”. Glendenning, Phys. Rev. D46 (1992),August 2004,Irene Parenti,Hybrid star: mass-radius,B=136,36 MeV/fm3,Hybrid Star: configuration,B=136,36 MeV/fm3,Strange Star: mass-radius,B=74,16 MeV/fm3,Strange Star: configuration,
11、B=74,16 MeV/fm3,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,Droplet potential energy:,nQ* baryonic number density in the Q*-phase at a fixed pressure P. Q*,H chemical potentialsat a fixed pressure P. surface tens
12、ion (=10,30 MeV/fm2),August 2004,Irene Parenti,Matter in the droplet,Flavor fractions are the same of the -stable hadronic system at the same pressure:,The pressure needed for phase transition is much larger than that without flavor conservation.,August 2004,Irene Parenti,Nucleation time,The nucleat
13、ion 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).,August 2004,Irene Parenti,The nucleation time dramatically depends on the value of the stell
14、ar central pressure and then on the value of the stellar mass.,The critical mass of metastable HS,We fixed the time of nucleation at 1 yr. The gravitational mass corresponding tothis nucleation time is called critical mass:,August 2004,Irene Parenti,Two families of compact stars,August 2004,Irene Pa
15、renti,Mass-Radius constraints,X-ray burster EXO 0748-676 Cottam et al., Nature 420, 2002z=0.35,X-ray pulsar 1E 1207.4-5209 Sanwal et al. ApJ 574, 2002, L61z=0.12-0.23,X-ray binary 4U 1728-34 Li et al. ApJ 527,1999,L51Very compact object,Mass-Radius constraints,Energy released,The total energy releas
16、ed in the stellar conversion is given by the difference between the gravitational mass of the initial hadronic star (Min=Mcr) and the mass of the final hybrid or strange stellar configuration (Mfin=MQS(Mbcr):,August 2004,Irene Parenti,The reaction that generate gamma-ray is:The efficence of this rea
17、ction in a strong gravitational field is:J. D. Salmonson and J. R. Wilson, ApJ 545 (1999) 859,How to generate GRBs,The energy released is carried out by pairs of neutrinos antineutrinos.,August 2004,Irene Parenti,Conclusions,Neutron stars (HS) are metastable to HS QS or to HS HyS,Our model explains
18、the connection and the time delay between SN and GRBs.,possible existence of two different families of compact stars:pure Hadronic StarsHybrid stars or Strange Stars,August 2004,Irene Parenti,Collaborators,Dr. Ignazio BombaciDr. Isaac Vidaa,Univ. of Pisa,INFN of Pisa,August 2004,Irene Parenti,Ref: I
19、. Bombaci, I. P., I. Vidaa arXiv:astro-ph/0402404Astroph. J., accepted,Dr. Alessandro DragoDr. Giuseppe Pagliara,Other collaborators:,Univ. of Ferrara,INFN of Ferrara,Appendix,August 2004,Irene Parenti,HADRONIC STARS(HS)HYBRID STARS(HyS)STRANGE STARS(SS or QS),Compact stars,conventional neutron starshyperon stars,August 2004,Irene Parenti,Probability of tunneling,
