The 6.67 hour period CCO in RCW 103: a descendant of Thorne-Zytkow object?. X. W. Liu, R. X. Xu, G. J. Qiao, J. L. Han, Z. W. Han, and X. D. Li, submitted to ApJ arXiv:1207.4687v1 [astro-ph.HE]. XiongWei Liu (Peking University) 刘雄伟 16 Aug. 2012, Urumchi. Background
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The 6.67 hour period CCO in RCW 103: a descendant of Thorne-Zytkow object?
X. W. Liu, R. X. Xu, G. J. Qiao, J. L. Han, Z. W. Han, and X. D. Li, submitted to ApJ
XiongWei Liu (Peking University)
16 Aug. 2012, Urumchi
The 6.67h period X-ray source in RCW 103
What is a TZO?
How to spin down?
Why looks like a CCO?
~1033 – 1035 erg s-1,
no radio or optical counterpart
SNR RCW 103
~2 kyr (Carter, 1997)
6.67-hour periodicity modulation (2006, De Luca)
any other periodicities with P >12 ms are excluded with high confidence
Long-term flux variability (2006, De Luca)
Period derivative(2011, Esposito)
Candidate 1: Orbit period of a binary?
Neutron star + low mass MS star
(2006, De Luca)
MNS=1.4 M⊙, Porbit=6.67h
black line: Mcom = 0.4 M⊙, e = 0.2;
red line: Mcom = 0.2 M⊙, e = 0.5.
wind velocity: 300 km s-1.
How could the company star survive from the supernova explosion and escape the observations?
Why didn’t find the spin period?
Candidate 2: Magnetar with a fallback disk?
(2006, De Luca)
magnetic field: 5×1015 G
disc mass: 3×10-5 M⊙
birth period: 0.3 s
Why doesn’t like other “magnetars”? (P: 2~12s)
AXP 0142, Disk (Wang 2006)
SGR 0418+5729, Disk spin-down (Alpar 2011)
Thorne-Zytkow Object (TZO) (Thorne & Zytkow, 1977):
A massive star with a degenerate neutron core
Structure of a TZO
20-200 TZOs existing in the Galaxy (Podsiadlowski et al. 1995),
But identified none.
Philipp et al. 1995, MNRAS
In the steady-burning phase
In the neutrino runaway phase
Spin-up to ~10ms
But they ignored the interaction between envelope and magnetosphere, and did not consider the out-flow
When the envelope particals go in to the core (inflow),
they are accelerated by the magnetosphere;
When some of them go out (ourflow),
they take away angular momentum from the core.
it is radiation press dominanted
it is not disk accretion
there is no Alphen radius
Structure of the convection envelope
Interaction between magnetosphere and particals,
Conservation of angular momentum: