Encounters
Low-Frequency QPO (LFQPO) ○｜encounter｜ENC｜20260911203354-03-•
Low-frequency QPOs (LFQPOs; roughly 0.1–30 Hz) have been detected on one or more occasions for 14 of the 18 BHBs considered in Table 4.2 of McClintock & Remillard (2006). They are important for several reasons. LFQPOs can have high amplitude (integrated rms/mean values of ) and high coherence (often ), and their frequencies and amplitudes are generally correlated with the spectral parameters for both the thermal and PL components (e.g., Muno et al. 1999; Sobczak et al. 2000a; Revnivtsev et al. 2000; Vignarca et al. 2003). With the exception of Cyg X–1, QPOs generally appear whenever the SPL contributes more than 20% of the flux at 2–20 keV (Sobczak et al. 2000a), which is one component of the definition of the SPL state (Table 2; McClintock & Remillard 2006).
Source: Remillard & McClintock 2006 ┃ X-Ray Properties… ⚬𓂃
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