We present an XMM-Newton analysis of the cataclysmic variable T Leo .
The X-ray light curve shows sinusoidal variation on a period P _ { x } equal to 0.89 ^ { +0.14 } _ { -0.10 } times the previously spectroscopically determined orbital period .
Furthermore , we find a signal in the power spectrum at 414 sec that could be attributed to the spin period of the white dwarf .
If true , T Leo would be the first confirmed superoutbursting intermediate polar ( IP ) .
The spin profile is double-peaked with a peak separation of about 1/3 spin phases .
This appears to be a typical feature for IPs with a small magnetic field and fast white dwarf rotation .

An alternative explanation is that the 414 sec signal is a Quasi-periodic Oscillation ( QPO ) that is caused by mass transfer variation from the secondary , a bright region ( “ blob ” ) rotating in the disc at a radius of approximately 9 R _ { \scriptscriptstyle wd } or – more likely – a travelling wave close to the inner disc edge of a dwarf nova with a low field white dwarf .

The XMM-Newton RGS spectra reveal double peaked emission for the O VIII Ly \alpha line .
Scenarios in the IP and dwarf nova model are discussed ( an emitting ring in the disc , bright X-ray spot on disc edge , or emitting accretion funnels ) , but the intermediate polar model is favoured .
Supported is this idea by the finding that only the red peak appears to be shifted and the ‘ blue ’ peak is compatible with the rest wavelength .
The red peak thus is caused by emission from the northern accretion spot when it faces the observer .
Instead , the peak at the rest wavelength is caused when the southern accretion funnel is visible just on the lower edge of the white dwarf – with the velocity of the accreting material being perpendicular to the line of sight .