Chandra and XMM-Newton X-ray Light Curves of RS Ophiuchi

Periodic oscillations in the Chandra and XMM-Newton X-ray light curve of RS Ophiuchi were found between the fourth and the seventh weeks after the 2006 outburst. The period drifted from 35.56 s on March 10 to 34.72 s on April 7. We present model calculations indicating that this phenomenon may be associated with the contraction of the white dwarf as it returns back to its pre-outburst state. However, we suggest that the X-ray flux modulated with the above periods is not emitted on the white dwarf itself, but it originated at the base of an outflow at the poles, which is rotating with the white dwarf.