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Low-Frequency QPOs, Self-Oscillations, and the Corona

Presentation #117.01 in the session Time-Domain Astrophysics.

Published onJul 01, 2023
Low-Frequency QPOs, Self-Oscillations, and the Corona

Low-frequency quasi-periodic oscillations (LFQPOs) are frequently present in the X-ray flux of black hole binaries. They appear in the power spectrum as coherent peaks. Their centroid frequencies are in the range of 0.01-10 Hz. Even though they have been identified in various sources and are readily measurable, the exact nature of their origin still eludes us. Thus far, no models have provided a comprehensive or satisfactory explanation. In this work, we propose that the origin of these low-frequency QPOs is related to the corona. Specifically, the LFQPOs are a result of self-oscillations. Self-oscillations can generate and maintain a periodic motion by a power source that lacks periodicity. Therefore, there is no need to find a periodic driver, as if it were the case for a resonant case. These self-oscillations associated with the corona can create the X-ray modulation detected as a QPO. Another instrumental consequence of this model is that it can shed light on the elusive physical properties of the corona itself.

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