Extended Data Fig. 4: Fractional RMS of the QPO in February 2023, August 2023, and March 2024 (first observation only) in two different energy bands – 0.3–2 keV and 2–10 keV.
From: Millihertz oscillations near the innermost orbit of a supermassive black hole

The fractional RMS was estimated using the normalization of the best-fitting Lorentzian for the QPO, and the error bars represent 1σ confidence intervals from the MCMCs. As in BHXBs, the fraction RMS increases with energy, suggesting that the Comptonized component is what is being modulated on the QPO frequency.