We present high time resolution optical photometric data of the polar VV Puppis obtained simultaneously in three filters ( u ’ , HeII \lambda 4686 , r ’ ) with the ULTRACAM camera mounted at the ESO-VLT telescope .
An analysis of a long 50 ks XMM-Newton observation of the source , retrieved from the database , is also provided .
Quasi-periodic oscillations ( QPOs ) are clearly detected in the optical during the source bright phase intervals when the accreting pole is visible , confirming the association of the QPOs with the basis of the accretion column .
QPOs are detected in the three filters at a mean frequency of \sim 0.7 Hz with a similar amplitude \sim 1 % .
Mean orbitally-averaged power spectra during the bright phase show a rather broad excess with a quality factor Q= \nu / \Delta \nu = 5-7 but smaller data segments commonly show a much higher coherency with Q up to 30 .
The XMM ( 0.5–10 keV ) observation provides the first accurate estimation of the hard X-ray component with a high kT \sim 40 keV temperature and confirms the high EUV-soft/hard ratio in the range of ( 4–15 ) for VV Pup .
The detailed X-ray orbital light curve displays a short \Delta \phi \simeq 0.05 ingress into self-eclipse of the active pole , indicative of a accretion shock height of \sim 75 km .
No significant X-ray QPOs are detected with an amplitude upper limit of \sim 30 % in the range ( 0.1–5 ) Hz .
Detailed hydrodynamical numerical simulations of the post-shock accretion region with parameters consistent with VV Pup demonstrate that the expected frequencies from radiative instability are identical for X-rays and optical regime at values \nu \sim ( 40–70 ) Hz , more than one order magnitude higher than observed .
This confirms previous statements suggesting that present instability models are unable to explain the full QPO characteristics within the parameters commonly known for polars .