Is PSR B0943+10 a low-mass quark star?
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Transcript of Is PSR B0943+10 a low-mass quark star?
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