Abstract
Significant (marginal) detections of periodic signals have been recently reported in 3 (4) Active Galactic Nuclei. Three of the detections were obtained from long EUVE light curves of moderate-luminosity Seyfert galaxies; the fourth was discovered in Chandra data from the low-luminosity Seyfert 1 galaxy NGC 4395. When compared with Cyg X-1, I find that the period is related to the luminosity as P∝ L2/3 rather than the expected one-to-one relationship. This result might be explained if the QPO is associated with the inner edge of the optically thick accretion disk, and the inner-edge radius depends on the source luminosity (or black hole mass). A discussion of uncertainties in the period detection methodology is also discussed.
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Leighly, K.M. X-RAY Periodicity in AGN. Astrophys Space Sci 300, 137–142 (2005). https://doi.org/10.1007/s10509-005-1189-4
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DOI: https://doi.org/10.1007/s10509-005-1189-4