1. SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu Renxin Xu ( 徐仁新 ) 1,2 1 School of Physics, Peking University ( ) 2 Kavli Institute for Astronomy and Astrophysics SINAP-CUSTIPEN Workshop on Clusters and Correlations in Nuclei, Nuclear Reactions and Neutron Stars December 14-18, 2015; Shanghai, China Supernova-produced Exotic Nuclei

2. Pulsar-like star is the rump left behind after supernova Normal baryonic matter is intensely compressed by gravity here! CBM Pulsar = Big exotic nucleus with 3-flavor symmetry? I could like to start with a question to explain my idea…

3. Why our baryonic matter is 2-flavor- (rather than 1- or 3-) symmetric? Note: Energy scale ~ 0.4 GeV < 1 GeV (~0.5 fm) pc ~  c ~ 200 MeV·fm Anthropic principle? S trange M atter NQCD!

4. Summary Strange Matter: bigger is diff.! Observational hints from SM? Conclusions SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

5. The symmetry-energy in liquid-drop model Five terms in mass formula of nucleus with Z protons and N neutrons (A = Z + N): E (Z, N) = volumesurfacesymmetryCoulombpairing Why does there exist symmetry-energy? Fermi gas of nucleons: still weakly interaction inside a nucleus? E pn EFEF  For non-relativistic neutrons and protons: p F  n 1/3, E F  n 2/3   Interaction really negligible? The kinetic term of Nuclear Symmetry Energy Strange Matter: bigger is diff.!

6. Fermi gas of nucleons: still weakly interaction inside a nucleus? Alternatively, stronger interaction there? (an analogy: NaCl) A note: electrons have to participate in 2-flavour symmetry matter! …but it doesn't matter for microscopic nuclei because of  em <<  s.. l ~ 10 -1 A ~ 10 4 fm kinematic motion is bound by EM interaction: p 2 /m e ~ e 2 /l Heisenberg’s relation: p  l ~    Electrons contribute negligible energy for micro-nuclei! 。 ~ 10 -5 MeV The potential term of Nuclear Symmetry Energy dominates! Strange Matter: bigger is diff.! 2-flavuor micro-nuclei is energetically favored! SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

7. 3-flvuor symmetry in gigantic/macro-nuclei? Huge Thomson atom if 2-flavour symmetry keeps... Huge Thomson atom with A > 10 9 disadvantages: though Coulomb energy could not be significant, but the Fermi energy of electrons: E F ~  cn 1/3 ~ 10 2 MeV! advantages if strangenization... (1) minimizing the electron’s contribution of kinetic energy, (2) maximizing the flavour number (only 2 if neutronization!). Micro-nucleus: 2 -f nucleon VS. Macro-nucleus: 3 -f quark-cluster Strange Matter: bigger is diff.! >> c ~ 10 3 fm SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

8. 2-f micro-nucleus VS 3-f macro-nucleus proton neutron f = 2f = 3 u u d u d d u s d d u s Strange Matter: condensed matter of quark-clusters! Strange Matter: bigger is diff.! ~ fm > c ~ 10 3 fm Quantum gas/liquid?Classical solid?! (an extension of the Bodmer–Witten conjecture: strange quark matter) SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

9. Summary Strange Matter: bigger is diff.! Observational hints from SM? Conclusions SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

10. CBM is produced inside massive stars after SN SN occurs due to gravitational energy release when nuclear power cannot stand against gravity. Where and observational evidence? Pulsar: neutron/strange? SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

11. Pulsars: Neutron star V.S. Strange star Observational hints from SM? What if normal baryonic matter is compressed by gravity in a core of massive evolved star, the nature of compressed baryonic matter (CBM)? It is very necessary to kill the electrons by weak interaction… SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

12. Pulsars: different models in the market… conventional Neutron Star light flavour symmetry: Strange Star Observational hints from SM? SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

13. 1 Quark-cluster stars Normal neutron stars Xu (2008) Pulsars: Observational hints? Observational hints from SM?

14. Subpulse drifting: PSG or self-bound surface? Bi-drifting: strong self-bound quark surface? Nonatomic spectra: quark surface? Clean fireball for SNE & GRB? Precessions of pulsars? Quake-induced free energy for AXP/SGRs? Non-thermal emission: bound strongly? Thermal emission: featureless & clear? Quark-cluster stars in a solid state? Obs. tests of stiff equation of state? Surface Global Observational hints from SM? SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

15. Observational hints from SM? SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

16. Watts et al. (2015) Hyperon puzzle? Quark-confinement? in this quark-cluster star model Observational hints from SM?

17. Photospheric radius expansion in 4U 1746-37 Constraints by PRE bursts of 4U 1746-37, on the assumption that the touchdown flux corresponded to L Edd, and the obscure effect is included. Li, et al. (ApJ, 2015) Compact stars: low-mass pulsar-like star? Observational hints from SM? SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

18. Nucita et al. (2014) H-like Ly-α Lines at E/eV : {10.2, 40.8, 91.8, 163.2, 255, 367.2, 500,., 826.2, 1020, 1234.2, 1468.8, 1723.8, 1999.2, 2295, 2611.2, 2947.8, 3304.8, 3682.2, 4080,...} The puzzling symbiotic X-ray system 4U 1700+24

19. 1.Red-shift: z ~ 0.009! 2.X-ray black body radiation area (A 1/2 ~ 10-10 2 m) reduce as L x decreases. 3.The mass function via by observing the G-type red giant company is only f o ~ 10 -5 M ⊙ ! ⇒ All 3 could be understood if M compact is only ~ 10 -2 M ⊙ unless geometrically fine-turn. Observational hints from SM? SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

20. To find clear observational evidence by  PSR mass measurements (M)  PSR moment of inertia measurements (I)  Discovering fastest spinning PSRs (P)  Magnetospheric activity (pulse-profile) Observational hints from SM? future… SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

21. Example of future facility ： ground-based FAST SKA

22. Pulsar science is elected as one of key projects  Xiangshan meeting S21: Chinese SKA“2+1”strategy “2”= HI & PSR “1”= others SKA“SRP” Example of future facility ： ground-based

23. + = HXMT  XTP eXTP ： 1 奇 2 星 3 极端 Example of future facility ： space-based

25. Summary Strange Matter: bigger is diff.! Observational hints from SM? Conclusions SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu

26. Conclusions Although normal micro-nuclei are 2-flavour symmetric, we argue that 3-flavour symmetry would be restored in macro/gigantic-nuclei compressed by gravity during a supernova. Strange matter is conjectured to be condensed matter of 3-flavour quark-clusters, and future advanced facilities (FAST/SKA, HXMT/eXTP) would provide clear evidence for strange stars. THANKS! SN-nuclei http://www.phy.pku.edu.cn/~xurenxin/ R. X. Xu