Collaborators: Sarmistha Banik (FIAS) Debarati Chatterjee (SINP)

1. Hadrons in Neutron StarsDebades BandyopadhyayCenter for Astroparticle PhysicsSaha Institute of Nuclear Physics,Kolkata, India. Collaborators: Sarmistha Banik (FIAS) Debarati Chatterjee (SINP)

2. Visionaries... Neutron stars have been predicted in 30s: L.D. Landau: Star-nuclei (1932) + anecdote Baade and Zwicky: neutron stars and supernovae (1934) (Landau) (Baade) (Chandrasekhar) (Zwicky)

3. Shapiro,Teukolsky (1983)

4. Landau paper BEFORE neutron discovery Physikalische Zeitschrift der Sowjetunion Vol. 1, No. 2, 285-188, 1932 Written: Feb. 1931, Zurich Received: Jan. 7, 1932 Published: Feb. 1932

5. Neutron Stars are one of the densest forms of matter in the observable universe. Neutron Star matter is cold and highly dense. The matter density in the core exceeds by a few times normal nuclear matter density. Observations of binary pulsars and isolated neutronstars provide informations about masses and radii. The theoretical mass-radiusrelationships of compact stars are directly compared with the measured masses and radii. Consequently, the composition and EOS of dense matter in a neutronstar interior may be probed.

6. Plan of the talk • Masses and Radii of neutron stars • Hyperon matter in neutron star • Kaons and antikaons in neutron stars • Astrophysics in FAIR • Outlook

7. BHs ? Page & Reddy (2006)

8. Glimpse of Dense Matter in EXO 0748-676 • Observations of thermonuclear X-ray bursts by XMM-Newton and Rossi X-ray Timing Explorer (RXTE), • Narrow absorption lines of n=2-3 transitions in H- and He-like Fe, in the average spectrum of 28 x-ray bursts with XMM- Newton, Ref: J. Cottam et al., Nature 420 (2002) 51 • Redshift z = (1 – 2 GM /c2 R)-1/2 – 1=0.35 • Line widths provide vrot=spin R = 2spinR • Burst oscillation due to spin modulation and recent detection of spin frequency spin=45Hz with RXTE, • Villarreal and Strohmayer, ApJ 614 (2004) L121 • Radius and Mass : R=9.5-15 km and M= 1.5-2.3 M Best fit values: R =11.5 km,M=1.8M

9. Double Pulsar System PSR J0737-3039 • First ever observed Double Pulsar System, Burgay et al., Nature 426 (2003) 531 • Keplerian parameters Porb=2.45 h, ap , e = 0.088,and To measured from the pulsar timing data. • Pulsar A has a spin period 22.7 ms and M=1.337 M; those of Pulsar B are 2.8 s and M= 1.25 M , • Accurate measurements of relativistic corrections to the Keplerian description, • Enormous bursts of gravitational waves.

10. Spin-Orbit Coupling in PSR J0737-3039A Measurements of spin-orbitcoupling: Two Possibilities, • Precession of the orbital plane about the direction of the total angular momentum • The amplitude of timing change:ta=a IA PsinAcos i , i=900 c MA a2 PA • Advance of periastron ktot = 3 02 [ 1+f002 – gsA0 sA - gsB0 sB] 1 – eT wheres = 2  c . 1 . I GPp m2 Damour and Schaefer (1988) Nuovo Cimento 101B • Moment of inertia, I  MR2 , constrains the EOS

11. Possible forms of exotic matter Structure of a neutron star xoti subatomic particles? ) n  10 14 g/cm3 Credit: D. Page

12. Hyperons • Hyperons produced at the cost of nucleons n + p  p +  + K0 , n + n  n +  - + K+ • Chemical equilibrium through weak processes p + e- +  e , n + e- - +  e  i = bi  n - qi  e • Threshold condition for hyperons  n - qi  e  mB* + gB 0 + gB 03 3 Ref:N.K. Glendenning ApJ 293 (1985) 470

13. J.Schaffner and I.N.Mishustin, PRC 53,1416 (1996) Equation of State

14. Parameters of the model

15. Hyperons in Neutron Stars

16. EOS including hyperons

17. Allowed EOS: M max theo = M highest obs • Softer EOS ruled out byEXO 0748 - 676

18. Kaons in nuclear medium • Kaplan & Nelson first predicted kaon condensation in dense matter • Kaos as well flow data point out that antikaons feel attarctive interaction in the medium Li et al. PRL 79 (1997) and S. Pal et al. PRC 62(2000) • It is repulsive interaction for kaons • Cosequently effective mass and in-medium energy of antikaons decrease • Antikaon optical potential depth is a debatable issue L. Tolos et al. PRC 74 (2006) 024903 E. Friedman & A. Gal arXiv:0710.5890

19. Bose-Einstein condensates • Processes responsible for p-wave pion condensate/ ompastars: n  p + -n p + K - e -- + ee- K - + e • Threshold condition for Bose condensation of mesons: ForK - K - = K -=e For-- = e J.B. Hartle, R.F. Sawyer & D.J. Scalapino, ApJ199 (1975) 471 A.B. Migdal , A.I. Chevnoutsan, I.N. Mishustin PLB83 (1979) 158 H.A. Bethe and G.E. Brown, ApJ 445 (1995) L129

20. N.K. Glendenning and J., Schaffner-Bielich, PRL 81(1998)& PRC 60 (1999)S. Banik and D. Bandyopadhyay PRC 64, 055805 (2001)

22. The Mixed Phase Gibbs phase rules PI = PII , I =II . Conditions of global charge neutrality ( 1 -  ) QI +  QII = 0 , Baryon number conservation nB = ( 1 -  ) nI +  nII Total energy density = ( 1 -  ) I +  II

27. With pion condensate, B. Kaempfer, J. Phys. A14 (1981) 1471

28. Composition in a neutron star

29. FAIR and Neutron Star Matter

30. Constraining Neutron Star Matter • Attempt to extract EoS from heavy ion collisions was made • Neutron star matter depends on the symmetry energy • The knowledge of the density dependence of symmetry energy is essential • Ratios of baryons and mesons might be good probes of the symmetry energy B.A. Li et al., Phys. Rep. (2008) Danielewicz, Lacey & Lynch, Science 298 (2002)

31. Symmetry Energy E (r,T,a) = E(r,T,a=0) + Esym(r,T) a2+ ... S. Banik ( in preparation)

32. Hot Neutron Stars See also V. Dexheimer et al., arXiv:0802.1999

33. Outlook • A strong interplay between the physics of dense matter in compact stars and the physics of dense matter in FAIR • Density dependence of the symmetry energy holds the key to the behaviour of matter at high density • FAIR might be able to shed light on hot neutron star matter