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A periodicity of 1 hour in X-ray emission from the active galaxy RE J1034+396


Active galactic nuclei and quasars are thought to be scaled-up versions of Galactic black hole binaries, powered by accretion onto supermassive black holes with masses of 106–109, as opposed to the 10  in binaries (here is the solar mass). One example of the similarities between these two types of systems is the characteristic rapid X-ray variability seen from the accretion flow1. The power spectrum of this variability in black hole binaries consists of a broad noise with multiple quasi-periodic oscillations superimposed on it. Although the broad noise component has been observed in many active galactic nuclei2,3, there have hitherto been no significant detections of quasi-periodic oscillations4,5,6. Here we report the discovery of an 1-hour X-ray periodicity in a bright active galaxy, RE J1034+396. The signal is highly statistically significant (at the 5.6σ level) and very coherent, with quality factor Q > 16. The X-ray modulation arises from the direct vicinity of the black hole.

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Figure 1: XMM-Newton light curve of RE J1034+396.
Figure 2: Folded light curve.
Figure 3: Power spectral distribution.


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M.G. was supported in part by the Polish MNiSW (NN203065933). C.D. acknowledges financial support through a PPARC senior fellowship.

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Gierliński, M., Middleton, M., Ward, M. et al. A periodicity of 1 hour in X-ray emission from the active galaxy RE J1034+396. Nature 455, 369–371 (2008).

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