EARLY PHASES OF DIFFERENT TYPES OF ISOLATED NEUTRON STAR

Two Galactic isolated strong X-ray pulsars seem to be in the densest environments compared to other types of Galactic pulsar. X-ray pulsar J1846-0258 can be in an early phase of anomalous X-ray pulsars and soft gamma repeaters if its average braking index is ~1.8–2.0. X-ray pulsar J1811-1925 must have a very large average braking index (~11) if this pulsar was formed by SN 386AD. This X-ray pulsar can be in an early phase of the evolution of the radio pulsars located in the region P ~ 50–150 ms and Ṗ ~ 10-14–10-16 ss -1 of the P–Ṗ diagram. X-ray/radio pulsar J0540-69 seems to be evolving in the direction to the dim isolated thermal neutron star region on the P–Ṗ diagram. Possible progenitors of different types of neutron star are also discussed.