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Welcome from Peking University !

Welcome from Peking University !. Astronomy Dept., School of Physics. 4 groups: Galaxies and Cosmology (Prof. Z. H. Fan) Planet nebula physics (Prof. X. W. Liu) AGN and supermassive BHs (Prof. X. B. Wu) Particle astrophysics (Prof. R. X. Xu). KIAA (Kavli inst. for A&A at Peking U.). ….

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Welcome from Peking University !

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  1. Welcome from PekingUniversity! Astronomy Dept., School of Physics 4 groups: Galaxies and Cosmology (Prof. Z. H. Fan) Planet nebula physics (Prof. X. W. Liu) AGN and supermassive BHs (Prof. X. B. Wu) Particle astrophysics (Prof. R. X. Xu) KIAA (Kavli inst. for A&A at Peking U.) … “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  2. Pulsars& Quark stars Renxin Xu (徐仁新) School of Physics, Peking University Talk presented at “Workshop on high energy astrophysics” July 25th, 2006.Astron. Dept., Nanjing Univ. “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  3. Not only is the Universe stranger than we imagine, it is stranger than we can imagine. ——Arthur Eddington What’s the nature of pulsars? • Thought conventionally to be normal neutron stars • But no convincing work (either theoretical from first principles or observational) has confirmed Baade–Zwicky’s original idea that supernovae produce neutron star • To be quark stars? “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  4. Summary • A historical note on pulsars • Obs. hints of quark stars? • Conclusions “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  5. It depends on laboratory physics laws to understand astrophysical phenomena! EoS of Stars Statistical Laws Main-sequent stars M-B statistics Fermion stars FD BE “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  6. A historical note on pulsars R. H. Fowler (1926, soon after FD) Degenerate pressure is not omnipotent in standing against the gravitational collapse Maybe there are stars with nuclear density after collapse? “Neutron” star S. Chandrasekhar L. Landau “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  7. A historical note on pulsars Pulsars (discovered in 1967) could be neutron stars? Walter Baade and Fritz Zwicky proposed in 1934 that supernovae could produce cosmic rays and neutron stars … A. Hewish “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  8. Quark? A historical note … • 1950s~1960s:A success in the classification of hadrons discovered in cosmic rays and in accelerators • M. Gell-Mann (1964): Quarks? ---- in mathematical description, rather than in reality. • Zweig (1964): in reality? Quarks? M. Gell-Mann (1969) “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  9. Quark? A historical note … • Chinese group (1966) • Experimental evidence for the last one: top quark in 1995

  10. A historical note on pulsars • Experimental evidence for asymptotic freedom “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  11. The Nobelprize in Physics (2004) 1973: SU(3) non-Abelian gauge theory  asymptotic freedom Frank Wilczek of the Massachusetts Institute of Technology. David J. Gross (L) of the University of California at Santa Barbara and his wife (R) H. David Politzer of the California Institute of Technology, Pasadena, California.

  12. A historical note on pulsars • What is Quark Matter? • Expected in QCD (QGP) (Hadron gas) To be a direct consequence of aympt. freedom A simple QCD phase diagram “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  13. A historical note on pulsars • Pulsars: quarkstars? • Ivanenko & Hurdgelaidze (1969) • Itoh (1970) • Bodmer (1971) • Asymptotic freedom • Witten (1984) • 1986: Haensel et al.; Alcock et al. “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  14. A historical note on pulsars • The structure of normal Neutron stars • Atmosphere • Outer crust • Inner crust • Neutron matter • Core？ Heiselberg 2002 “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  15. A historical note on pulsars Neutron Stars v.s. QuarkStars http://chandra.harvard.edu/photo/2002/0211/0211_illustration.pdf “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  16. A historical note on pulsars • Solid Quark Matter?  QGP B Solid? Liquid? Gas? Hadron 0 QCD phase? T Phase diagram for CO2 “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  17. A historical note on pulsars A Solid-quark-matter conjecture Xu 2005 Similar to the superconductivity symmetry broken spontaneously • T-dom. • D-dom. Solid QM? “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  18. Members of the family of pulsars … Accretion-powered X-ray pulsars X-ray bursts Compact center objects What’s really the nature of pulsars? Radio pulsars AXP/SGR Dim thermal “Neutron” stars “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  19. Historical note on pulsars: Summary The nature of pulsars depends on physics of matter at supranucleardensity which is still unknown! Normal neutron stars? { Pulsars { Fluid? Quark stars? (strange or not) Solid? “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  20. Still a challenging topic … to answer a question arising ~ 80 years ago! Face-to-face … ones with big-names … R. H. Fowler S. Chandrasekhar L. Landau … “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  21. Summary • A historical note on pulsars • Obs. hints of quark stars? • Conclusions “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  22. Observational hints of quark stars? • SNE: bare quark star is better (Chen, Xu 2006) • Non-atomic features? e.g. RXJ1856 (Xu 2002, 2003) • (Bi)drifting subpulse: sparking (Xu…’99, Qiao…’04) • Radio& -ray profiles: annular gap (Qiao…’04a, …) • Glitches & slow-glitches: (Zhou… 2004, Xu 2006) • … (e.g., free-precessions, low-mass quark stars) “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  23. R. Buras, M. Rampp, H.-Th. Janka, K. Kifonidis, 2003, PRL90, 241101 “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  24. Photon-driven supernovae? • The bare quark-surface helps supernovae? -luminosity is not limited by the Eddington limit: Due to the chromatic confinement, the thermal luminosity on the quark surface could be as high as Bare quark surface should be energetic source! “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  25. Photon-driven supernovae? • Model of photon-driven supernovae/GRBs Low baryon contamination! “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  26. Sharp difference: quark matter surface! • Non-atomic line in thermal emission Why is the spectrum observation soimportant? • Red shift Nuclear reaction  Pressure broadening Observational competition: Who isTHE FIRST? “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  27. Sharp difference: quark matter surface! Observations: Featurelessspectra! Xu (2002) “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  28. Sharp difference: quark matter surface! NASA News release (2002/4/10): RX J1856 a strange star? Chandra “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  29. (Bi)drifting subpulse : Sparking! • Drifting subpulses in radio emission PSR 0943+10 Deshpande & Rankin 1999 “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  30. (Bi)drifting subpulse : Sparking! • Ruderman-Sutherland (1975) model • Vaccum-gap sparking  Vd ~ c (EB/B2) • RS requires: EB>~10keV&B<0 • Difficulties in RS model • Bounding energy of neutron stars: EB<10keV • Why haven’t we observe two distinct kinds of _pulsar radio emission (B<0, >0)? • Advantages of the bare strange star idea • EB   for any B • keeps the RS scenario of vacuum gap sparking “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  31. (Bi)drifting subpulse : Sparking! Bi-drifting subpulses Qiao et al. 2004, ApJL “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  32. Summary • A historical note on pulsars • Obs. hints of quark stars? • Conclusions “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  33. Conclusions • Pulsars are not boring giant nuclei! • In addition to test GR, pulsars are also useful to test and to improve the fundamental strong interaction. • Possibleevidence for quark stars are proposed. • A solid state of quark matter is suggested. “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  34. Thanks a lot and Hope to receive your comment-suggestion Any time Email: r.x.xu@pku.edu.cn “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

  35. Xu (COSPAR2004), 2006, Adv. in Space Research, 37, 1992 (astro-ph/0410652) Wang et al. Nature 440 (2006) 772-775 (astro-ph/0604076) “Pulsars and Quark Stars” http://vega.bac.pku.edu.cn/rxxu R. X. Xu

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