Neutron stars in Microquasars
  We discuss the "basic" condition for an accreting neutron star to become a microquasar, i.e. ejecting relativistic particles orthogonal to the accretion disk instead of confining disk-material down to the magnetic poles and creating the two emitting caps typical for a X-ray pulsar. Jet creation is prevented for B >/= 10^12 G independent of the accretion rate. This excludes the possibility for a classic X-ray pulsar to develop a "microquasar-phase" and is consistent with the lack of radio emission from such pulsar systems. Millisecond accretion-powered pulsars, on the contrary, may show a "microquasar-phase", where B < 10^7.5 G is valid, whereas the limit for Z sources is B < 10^8.2 G. The implication of our analysis is that the jet might be the suitable agent of angular momentum sink for millisecond accretion-powered pulsars. 
M. Massi