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

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

4. Equation of States
Self-bound or
Gravity bound

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

6. How to constrain the M-R of NS?
Redshift measurement
Pulse Profile in X-ray pulsars
Atmosphere emission in qLMXBs
PRE bursts

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

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

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

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

11. Fan Beam +
Pencil Beam + .
Leahy 2004

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

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

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

15. Summary Redshift M/R Pulse Profile in X-ray pulsars M/R
Atmosphere emission in qLMXBs M-R
PRE bursts

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

17. PRE X-ray Burst Photospheric Radius 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
Guver et al. 2012

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

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

20. Results
4U /NGC 6441

21. Obscuration
4U /NGC 6441

22. 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