Variability In A Low-Mass AGN: Oscillation Or Eruption?

Abstract

Following the discovery of a new class of X-ray variability seen in four galaxies, dubbed Quasi-Periodic Eruptions (QPEs), we reconsider the variability seen in the low-mass AGN 2XMM J123103.2+110648 to ascertain whether it should be considered the fifth QPE host galaxy. We apply the autocorrelation function to two archival XMM-Newton observations to determine characteristic timescales for variability of $\sim$ 13.52 ks and $\sim$ 14.35 ks. The modelling of lightcurves, both folded at these timescales and unfolded, indicates that a Gaussian model is preferable over a sinusoidal model, with average durations for the bright phases of 6.17 ks and 7.69 ks. In a broad 0.2-1.0 keV band the average amplitude of the bright phases was found to be 2.86 and 8.56 times the quiescent count rate. The pattern of variability seen in 2XMM J123103.2+110648 cannot be definitively declared as a series of Quasi-Periodic Eruptions. Instead, this suggests there may be a continuum of quasi-periodic variability ranging from eruptions to oscillations being caused by a single mechanism. This offers the possibility of finding further sources that continue to bridge the gap between QPEs and Quasi-Periodic Oscillations. A targeted analysis of 47 observations of 11 other low-mass AGN $(log(M_{BH})\lesssim 6)$ found no evidence of QPE or QPO-like behaviour in a sample of other similar mass objects.

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Cited by in corpus (2)

• Alive and kicking: A new QPE phase in GSN 069 revealing a quiescent luminosity threshold for QPEs
• QPE or QPO? -- Quasiperiodic Activity in Low-Mass Galaxy Nuclei