Poster Presentation

Characterizing the Time-Frequency Properties of Quasi-Periodic Oscillations around Black Holes

Yi-Hao Su, Yi Chou, Chin-Ping Hu, Ting-Chang Yang, Hung-En Hsieh (Institute of Astronomy, National Central University, Taiwan)

We present the results of Lomb-Scargle spectrograms and Hilbert-Huang transform (HHT) of quasi-periodic oscillations (QPOs) around two different mass-scale black holes. The resultant Hilbert spectra of the 4 Hz QPO in the black hole X-ray binary XTE J1550-564 demonstrate that the QPO is composed of a series of intermittent signals appearing occasionally. Comparing with the ~5 mHz QPO around the supermassive black hole in Swift J1644+57, we conclude that the intermittent feature of both QPOs rules out interpretations of continual frequency modulation.