Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the Small Magellanic Cloud

摘要: We report on the long term average spin period, rate of change period and X-ray luminosity during outbursts for 42 Be binary systems in Small Magellanic Cloud. also collect calculate parameters each system use this data to determine that all contain a neutron star which is accreting via disc, rather than wind, if these stars are near equilibrium, then over half them, including with periods about 100 seconds, have magnetic fields quantum critical level 4.4x10^13 G. If not close their inferred be much lower, order 10^6-10^10 G, comparable low mass binaries. Both results unexpected implications field decay isolated population.