1. 西华师范大学 China West Normal University
FAST Pulsar Symposium 3
From TZO to CCO?
X. W. Liu, R. X. Xu, G. J. Qiao, J. L. Han, Z. W. Han, X. D. Li, and E. P. J. van den Heuvel. arXiv [astro-ph.HE], submitted to ApJ
刘雄伟 Xiongwei Liu
西华师范大学 China West Normal University

2. Background Discussion From TZO to CCO 1. A very strange CCO 2. The TZO
1. How to brake-down quickly?
2. How to become visible?
3. Theory VS Observation
Discussion

3. Background

4. 1. A very strange CCO The extremely long period CCO: 1E1613
Central Compact Object in supernova remnant (CCO)
6.67 hour period. Periodicities with P > 12 ms are excluded at the 99% confidence level (De Luca et al. 2006, Nature)
SNR RCW 103
Age: 2000 yr
(Carter 1997)
1E1613
(Tuohy 1980)
No IR or optic counterpart
Origin still unknown!

5. 1. A very strange CCO Origin from a TZO? What is the origin？
Orbital period?
Spin period?
Magnetar + disk
B: 5×1015 G, Porigin: 0.3 s, Disk mass: 3×10-5 M⊙
(De Luca et al. 2006)
Not agree with the magnetar theory and observation
Other possibility：
Origin from a TZO?

6. 2. The TZO Thorne-Zytkow Object (TZO) (Thorne & Zytkow, 1977):
——A Red Giant with a NS core
Common envelope
Huge,
Slowly spin,
Convective,
NS core
Origin from the merger of a NS with its companion
Appearance:
Giant : < 9 solar mass
Supergiant: > 11 solar mass

7. 2. The TZO Thorne-Zytkow Object (TZO) (Thorne & Zytkow, 1977):
Prediction: about TZOs in the Milky Way
Observation: Found nothing in the Galaxy
A candidate in the Small Magellanic Cloud
(Podsiadlowski et al. 1995)
(Levesque et al. 2014)

8. From TZO to CCO

9. Core of a TZO:
Original spins fast
Invisible
CCO (1E1613):
Spins very slowly
visible
1. How to quickly brake-down to very slowly?
2. How to become visible?

10. 1. How to quickly brake-down to very slowly?
Coupling between the magnetic field
of the NS core and the ionized envelope.
Brake-down timescale:
T < 2000 yr with normal parameters. Very quickly.
Convection of the envelope takes away the angular momentum from inner region to outer region.
The NS core can be braked-down to very slowly.

11. 2. How to become visible?
The core could be visible only if the envelope was destroyed. (The envelope has a small gravitational binding energy, ergs, which is easy to be destroyed)
Both the stellar wind and the instable nuclear burning can destroy the envelope within 2000 years;
(Ouyed 2002)
(Cheng et al. 1998)
Quark nova or the phase thansition of a baryon crust can destroy the envelope immediately.

12. 3. Theory VS Observations
The destroyed envelope could become a SNR like shell, or mix with the previous SNR. (RCW 103?)
Naturally form the other observational features (the remnant, age, proper motion, X-ray radiation)
Self-consistent!

13. Discussion

14. Discussion
One test:
The abundances of the characteristic elements created in TZO phase are different from that in normal SNRs
Two advantages:
strong torque, brake-down very quickly
envelope spins very slowly, brake-down to very slowly
Three significances:
Can solve the riddle of origin of the long period CCO
Verify the existence of TZOs (also the non-detection of CCO in the galaxy)
Provide limitation to the theory of the evolution of common envelope

15. 西华师范大学
西华师范大学天文台（青海德令哈）
Thanks!