A search for the Formula frequency in the X-ray light curves of intermediate polars

Wynn & King have shown that discless accretion gives rise to modulations at either the $\omega - \Omega\enspace \text {or}\enspace 2\omega - \Omega$ frequencies in the X-ray light curves of intermediate polars. However, the EXOSAT archive shows no sign of a $2\omega - \Omega$ modulation in any of the systems observed. An $\omega - \Omega$ modulation larger than half the spin-pulse amplitude has been seen only once, while generally the $\omega - \Omega$ pulses are weak or absent. Unless the spin periods are misidentified, this implies that the intermediate polars accrete predominantly, though in some systems not exclusively, through disks.