QPO in RE J1034+396: model constraints from observed trends
  We analyze the time variability of the X-ray emission of RE J1034+396, an
active galactic nucleus with the first firm detection of a quasi-periodic
oscillations (QPO). Based on the results of a wavelet analysis, we find a drift
in the QPO central frequency. The change inthe QPO frequency correlates with
the change in the X-ray flux with a short time delay. Linear structures such as
shocks, spiral waves, orvery distant flares seem to be a favored explanation
for this particular QPO event.
