Possible ~0.4 hour X-ray quasi-periodicity from an ultrasoft active galactic nucleus

摘要: RX J1301.9+2747 is an ultrasoft active galactic nucleus (AGN) with unusual X-ray variability that characterized by a long quiescent state and short-lived flare state. The flares are found to recur quasi-periodically on timescale of 13-20 ks. Here, we report the analysis light curve in from two XMM observations spanning 18.5 years, along discovery possible quasi-periodic oscillation (QPO) period ~1500s. QPO detected at same frequency independent observations, combined significance >99.89%. agreement relation between black hole mass (M_BH) has been reported previous works for AGNs Galactic binaries (XRBs). stable over almost decades, suggesting it may correspond high-frequency type XRBs originates, perhaps, certain disk resonance mode. In 3:2 twin-frequency model, our best estimate M_BH range implies maximal spin can be ruled out. We find all so far display quasi-periodicities emission, link part extreme phenomenon component. This indicates could most promising candidates future searches periodicities.