1. Effects of rotochemical heating on the thermal evolution of superfluid neutron stars
HuaZhong Normal University
Chun-Mei Pi & Xiao-Ping Zheng

2. Outline Equation of state and model of superfluidity
Rotochemical heating
The thermal evolution of NSs
Conclusions

3. Equation of state
Core: APR EOS
Crust: BPS EOS

4. Model of nucleon superfluidity
Gusakov et al.(2005),MNRAS,363,555

5. Rotochemical heating NS spin-down (decreasing centrifugal force)
Chemical (“beta”) equilibrium sets relative number densities of particles (n, p, e, ...) at different pressures
Compressing a fluid element perturbs equilibrium
Non-equilibrium reactions tend to restore equilibrium
“Chemical” energy released as neutrinos & “heat”
Reisenegger 1995, ApJ, 442, 749

6. The neutrino emissivities & net reaction rates:
Chemical imbalance:
The neutrino emissivities & net reaction rates:
The energy dissipation rate:
Detailed model: Fernández & Reisenegger 2005, ApJ, 625, 291

7. The thermal evolution of NSs
The energy and flux equations
The thermal evolution equation with the approximation of isothermal interior

9. Three distinct cooling types : slow, moderate and fast cooling
The transition from slow cooling to moderate one is sharp
Neglecting the heating effects
Gusakov et al.(2005),MNRAS,363,555

10. Taking the rotochemical heating into account
The vacancy region will no longer exist
Three distinct cooling types become ambiguous

11. Conclusions
The rotochemical heating delays the cooling of superfluid neutron stars considerably .
The picture of thermal evolution becomes completely different when including the rotochemical heating.
The results are consistent with observations.

12. Thank you