Is PSR B0943+10 a low-mass quark

star?Youling Yue( 岳友岭 ), Xiaohong Cui( 崔晓红 )

and Renxin Xu( 徐仁新 )

Astronomy department, Peking University

at Nanjing 2006.8

contentscontents• Pulsar, neutron star, quark star• PSR B0943+10, quark star model, inclina

tion angle effect• Conclusion

What is pulsarWhat is pulsar• Neutron star

– Normal or Mixed/hybrid (quark core)

• Quark star– Bare or with thin

crust– Solid (stronger

GW emission?) or fluid

• Which one(s)?Observation

Bejger and Haensel 2003

Bejger and Haensel 2003

Deshpande & Rankin 1999

PSR B0943+10 (P =1 s), one of the best-studied drifting pulsar

• We focus on pulsar sub-pulse drifting and polar gap model

Pulsar emission modelsPulsar emission models• polar gap (e.g., Ruderman & Sutherland 1975/RS75)

successful to sub-pulse drifting • space charge-limited flow (e.g., Arons & Scharle

menn 1979)

• outer gap (e.g., Cheng et al. 1986) • core gap and annular gap (e.g., Qiao et al. 2004)

• …

Success of polar gap model (RS75)Success of polar gap model (RS75)

RS75

e+

e-

Edwards and Stappers 2002

earth

hot spot

In x-ray band

To test the modelTo test the model

• X-ray band observation (Zhang et al. 2005)

• A_polar = 103 m2 (observation)

• A_polar = 6x104 m2 (theory, for R=10 km pulsar)

Zhang et al. 2005

To solve the problemTo solve the problem

• modification of polar gap model

• a low mass bare strange quark star – small radius (R = 2.6 km to fit the observatio

n) – No binding energy problem

binding energy of ion is nearly infinity (Xu & Qiao 1999)

advantagesadvantages• RS75 ：

– Only work when – the binding energy problem, need strong B

• Our model:– Work for both – Quark star has strong enough binding energy

(binding by strong interaction)

> 0< 0 and

Problems from potential dropProblems from potential drop

0

Last open field line

• Phi< 1012 V (critical potential drop)

Considering inclination angleConsidering inclination angle

0

Last open field line

Results:Results:

Inclination angleInclination angle

A= 103 m2

rho = 2rho_n

Phi is well above 1012 V

In the parameter space

conclusionconclusion• PSR B0943+10 could be a quark star.• The potential drop will be ~100 times

larger when considering inclination angle effects.

Thank you

Deshpande & Rankin 2001