2025ApJ...989...59X

Quasiperiodic oscillations (QPOs) in active galactic nuclei (AGNs) provide a powerful tool for probing the structure of the innermost accretion flow and corona around supermassive black holes. RE J1034+396, the most prominent AGN known to host an X-ray QPO, exhibits both short-term and long-term QPO evolution, offering a unique opportunity to investigate accretion disk and corona physics through its temporal behavior. We report a possible long-term (∼92.2 days) cyclic evolution of the QPO in RE J1034+396, joining the detected QPO (∼3730 s) and its short-term (∼17 ks) modulation to form a possible QPO triplet, which is potentially the first such structure identified in an AGN. By applying the relativistic precession model to the QPO triplet, we constrain the black hole mass to $1.{7}_{-0.8}^{+0.9}\times 1{0}^{6}\,{M}_{\odot }$, consistent with independent estimates, and find a low dimensionless black hole spin of $0.01{7}_{-0.012}^{+0.028}$. We propose an exploratory model that involves a quasiperiodic ultrafast outflow (UFO) within the framework of the relativistic precession model, explaining the QPO lag reversal, the modulation of hard-band QPO amplitude by soft-band flux, and the long-term evolution of timing properties. Supporting evidence includes blueshifted emission and absorption lines indicating a strong UFO at ∼0.3c. This work provides new insights into the inner regions of AGN accretion disks and motivates further efforts in both numerical modeling and high-cadence timing observations.