1. Simulation of the Recycled Pulsar Evolution Pan Yuanyue, Wang Na and Zhang Chengmin, Xinjiang Astronomical Observatory, CAS, Urumqi, China National Astronomical Observatories, CAS, Beijing, China What is the bottom field ? Why is it close to 10 8 G, but not 10 6 G ? The bottom field is determined by: Magnetosphere radius R M = Star radius R (R M is defined by the accretion rate Mdot, magnetic field B) It can be written as: its relation to the asccretion rate as B f ∝ M d 0.5. B f =3×10 8 G is for: Eddington accretion rate, M=1.4M ⊙ and R=15 km B f =3×10 7 G is for: 1% Eddington accretion rate, … E-mail: panyuanyue@xao.ac.cn In the binary system, with the accreion mass provided by the companion, the NS magneitc field (B) decays and the spin period (P) is spun up. If the accretion mass is about ~0.2 solar mass (Zhang et al. 2011 ), a NS can eovlve to a MSP. The model of the accretion induced the magnetic field decay can be written as: See, e.g. Cheng K.S. and Zhang C.M. 1998, 2000; Zhang C.M. and Kojima Y. 2006; etc. Formation of millisecond pulsar (MSP) in the binary system Accreted matter spins-up the star, Accreted matter Buries its B-field, e.g. Bhatcharya & vean den Heuvel 1991 The first millisecond accretion powered X-ray pulsar was discovered by RXTE: SAXJ 1808.4- 3658, P=2.5 ms. See, Wijnands & van der Klis 1998 The first double pulsar system PSR J0737-3039AB was discovered by Parkes 64m radio telescope, and its MSP is a sample of recycled PSR, see, e.g. Lyne, AG, et al 2004, and its evolution was commented by van den Heuvel 2004, A: MSP, B~10 9 G, P=23 ms; B: PSR, B~10 12 G, P=2.8 s 2160 pulsars are plotted in the B-P diagram, data from ATNF Pulsar Catalogue in March of 2013. B~10^(11-14)G, P~30ms−8.5s for normal PSRs and B~10^(7.5−9)G, P~(1.4−20)ms for MSPs. To compare the simulated recycled PSRs with the observed samples, we set the different accretion evolutionary ; life time (T), initial and boundary conditions of NSs. Monte Carlo method is employed, which obeys the Gaussian distribution: The sumulated results are plotted in the B-P diagram: KS test for the simulated data (red dot line) with the observed data (black line): Results 1. The results of KS test for the simulated and observed data are real, that is to say the magnetic evolution model we used can describe the NS evolution. 2. The distribution of the recyceld PSRs are the independence of the initial conditions, such as the initial spin period and magnetic field. 3. The accretion mass can mainly affects the distribution of the recyceld PSRs. References Alpar M.A., et al. 1982, Nature, 300, 728 Bhattacharya D., van den Heuvel E. P. J., 1991, Phys. Rep., 203, 1 Cheng K.S. & Zhang C.M., 1998, A&A, 337, 441 Cheng K.S. & Zhang C.M., 2000, A&A, 361, 1001 Lyne A. G. et al., 2004, Science, 303, 1153 Pan Y.Y., Wang N. & Zhang C.M., 2013, ApSS, 346,119 Pan Y.Y. & Wang N., 2013, IAUS, 291, 462 Stairs I. H., 2004, Science, 304, 547 Taam R. van den Heuvel E. P. J., 1986, ApJ, 305, 235 Tauris M., Langer N. & Kramer M., 2012, MNRAS, 425, 1601 van den Heuvel E. P. J., 2004, Science, 303, 1143 Wijnands R., van der Klis M., 1998, Nature, 394, 344 Zhang C. M., Kojima Y., 2006, MNRAS, 336, 137 Zhang C. M. et al., 2011, A&A, 527, 83