A search for the 2omega-omega frequency in the X-ray light curves of intermediate polars.

Abstract

Wynn and King (1992) have shown that diskless accretion gives rise to modulations at either the omega-Omega or 2omega-Omega frequencies in the X-ray light curves of intermediate polars. However, the EXOSAT archive shows no sign of a 2omega-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.