2002ApJ...565..447R

We present evidence that the power-law part of the quiescent X-ray emissions of neutron stars in low-mass X-ray binaries is magnetospheric in origin. It can be very accurately calculated from known rates of spin and magnetic moments obtained from the ∼10³-10⁴ times brighter luminosity at the hard spectral state transition. This strongly suggests that the spectral state transition to the low hard state for neutron stars is a magnetospheric propeller effect. We test the hypothesis that the similar spectral state switches and that quiescent power-law emissions of the black hole candidates might be magnetospheric effects. In the process we derive proposed magnetic moments and rates of spin for them and accurately predict their quiescent luminosities. This constitutes an observational test for the physical realization of event horizons and suggests that they may not be formed during the gravitational collapse of ordinary matter.