Radio pulsar and accretion regimes of rapidly rotating magnetic neutron stars in early-type eccentric binaries

Rapidly rotating magnetic neutron stars in eccentric binary systems containing an early type star provide a unique opportunity to investigate the interplay between radio pulsar, stellar wind and accretion phenomena. We summarise the radio pulsar-dominated and the accretiondominated regimes, discussing how the transition from one regime to another can take place as a result of the varying orbital distance and relative velocity along the orbit, as well as changes of the wind characteristics. We derive the conditions under which the two known B star/radio pulsar binaries (PSR 1259–63 and PSR J0045–7319) can undergo a transition to the accreting regime. A strong increase of the mass loss ouflow from the companion is required, just to cause the onset of accretion onto the magnetospheric boundary. We also show that the X–ray transient A0538–66 is likely to undergo transitions from the accreting neutron star regime, to the regime of accretion onto the magnetosphere. These two regimes might correspond to the high ( > ∼ 10 38 erg s) and the low-luminosity (< 10 erg s) outbursts observed from this source. A radio pulsar might become detectable in the long quiescent states of A0538–66. A new model of the enigmatic high-energy binary LS I +61 303 involving accretion onto the magnetosphere is also presented.