We report the discovery of 8.5 \sigma high-frequency quasi-periodic oscillations ( HFQPOs ) at 66 Hz in the RXTE data of the black hole candidate IGR J17091–3624 , a system whose X-ray properties are very similar to those of microquasar GRS 1915+105 .
The centroid frequency of the strongest peak is \sim 66 Hz , its quality factor above 5 and its rms is between 4 and 10 % .
We found a possible additional peak at 164 Hz when selecting a subset of data ; however , at 4.5 \sigma level we consider this detection marginal .
These QPOs have hard spectrum and are stronger in observations performed between September and October 2011 , during which IGR J17091–3624 displayed for the first time light curves which resemble those of the \gamma variability class in GRS 1915+105 .
We find that the 66 Hz QPO is also present in previous observations ( 4.5 \sigma ) , but only when averaging \sim 235 ksec of relatively high count rate data .
The fact that the HFQPOs frequency in IGR J17091–3624 matches surprisingly well that seen in GRS 1915+105 raises questions on the mass scaling of QPOs frequency in these two systems .
We discuss some possible interpretations , however , they all strongly depend on the distance and mass of IGR J17091-3624 , both completely unconstrained today .