Extended Data Fig. 2: 2–10 keV PSDs for the 4 observations taken in July-August 2022.
From: Millihertz oscillations near the innermost orbit of a supermassive black hole
Left Four Panels: Unbinned PSDs from the 2–10 keV light curves with 20s binning for the 4 observations taken in July-August 2022 (ObsIDs 0902590201, 0902590301, 0902590401, 0902590501). The resulting MCMC fit to a power-law or Lorentzian broadband noise model is shown in orange or purple, respectively, with the 1σ confidence intervals shown as shaded regions. This model is fit simultaneously to all of these observations with all parameters tied. The bottom two panels show the data divided by the power-law and Lorentzian models. All four observations show an excess near 0.9 mHz. Rightmost Panel: Binned PSD created by averaging the individual PSDs at each frequency and then binning n = 6 neighbouring frequency bins. The resulting simultaneous fits to the broad band noise are shown again, solely for visual purposes. There is a clear, but broad, excess around 0.9 mHz.
