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The mass and radius of neutron star in 4U 1746-37

Q uark and C ompact S tars 2014. The mass and radius of neutron star in 4U 1746-37. Zhaosheng Li ( 李兆升 ) Department of Astronomy Peking University. 2014-10-20. Outlines. Why ? How to constrain M-R of NS in LMXB ? The M - R of NS in 4U 1746-37. Equation o f S tates.

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The mass and radius of neutron star in 4U 1746-37

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  1. Quark and Compact Stars 2014 The mass and radius of neutron star in 4U 1746-37 Zhaosheng Li (李兆升) Department of Astronomy Peking University 2014-10-20

  2. Outlines • Why? • How to constrain M-R of NS in LMXB? • The M-R of NS in 4U 1746-37

  3. Equation of States Self-bound or Gravity bound

  4. Main sequence NS binaries Mass WD-NS binaries DNS binaries Black widow pulsar X-ray/Optical binaries Anna Watts et al.2014

  5. How to constrain theM-R of NS? • Redshift measurement • Pulse Profile in X-ray pulsars • Atmosphere emission in qLMXBs • PRE bursts

  6. LMXB transient source “Switched on”: Accretion outburst “Switched off”: Quiescence

  7. Gravitational Redshift • EXO 0748-676 (XMM-Newton) Z=0.35 Fe XXVI (Hα) 9.518, 9.533, 9.579 9.675, 9.690, 9.73813.0 Fe XXV (He-like) O VIII Cottam et al. (2002)

  8. Only once in EXO 0748-676 Cottam et al. (2008) None detection of absorption line !

  9. Pulse Profile in X-ray Pulsars NICER, Gendreau et al. (2012)

  10. Fan Beam + Pencil Beam + . . . Leahy 2004

  11. qLMXBs in Globular Clusters Deep Crustal Heating Brown et al. (1998) nsatmos Guillot et al. (2013)

  12. qLMXBs in Globular Clusters nsatmos Guillot et al. (2013) Lattimar & Steiner (2013)

  13. qLMXBs in Globular Clusters nsatmos H/He atmosphere Guillot et al. (2013) Lattimar & Steiner (2013)

  14. Summary • Redshift M/R • Pulse Profile in X-ray pulsars M/R • Atmosphere emission in qLMXBsM-R • PRE bursts

  15. Type I vs. Type II X-ray burst • Type I (nuclear burning) • Type II (accretion event) Sala et al.2012 MXB 1730-335 Rapid Burster

  16. PRE X-ray Burst PhotosphericRadius Expansion Expansion->Contraction->Cooling The radiation pressure is larger than the gravitational one. Photospheric layers are lifted off the surface by the radiation pressure. 4U 1728-34 Guver et al. 2012

  17. Mass-Radius confidence intervals • Bayes(Ozel et al.(2009,2010)) or Monte-Carlo simulation

  18. RXTE Obs. Of 4U 1746-37/NGC6441 Dipping binary Low touchdown flux (luminosity) Low mass NS?

  19. Results 4U 1746-37/NGC 6441

  20. Obscuration 4U 1746-37/NGC 6441

  21. Conclusions • An extremely low mass NS may exist in 4U 1746-37 • EoSs can be effectively tested from low mass NS Formation Lower limit mass (self-bound or gravity bound NS) Radius

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