We report the discovery of the correlated optical/X-ray low-frequency quasi-periodic oscillations ( QPOs ) in black hole binary SWIFT J1753.5–0127 .
The phase lag between two light-curves at the QPO frequency is close to zero .
This result puts strong constraints on the nature of the optical emission in this object and on the origin of the QPOs in general .
We demonstrate that the QPO signal and the broadband variability can be explained in terms of the hot accretion flow radiating in both optical and X-ray bands .
In this model , the QPO appears due to the Lense-Thirring precession of entire flow , while the broadband variability in the optical is produced by two components : the hot flow and the irradiated disc .
Using the phase-lag spectra , we put a lower limit on the orbital inclination i \gtrsim 50 \degr , which can be used to constrain the mass of the compact object .