Possible ~ 1 hour quasi-periodic oscillation in narrow-line Seyfert 1 galaxy MCG--06--30--15

TL;DR

This paper reports the detection of a potential 1-hour quasi-periodic oscillation in the X-ray emission of the Seyfert galaxy MCG--06--30--15, using data from XMM-Newton, suggesting possible accretion-related variability.

Contribution

First detection of a ~1-hour QPO in a narrow-line Seyfert 1 galaxy using multiple analysis techniques, indicating persistent oscillatory behavior.

Findings

Detected a ~3670s QPO with 3σ significance.

QPO signal persisted throughout the observation.

Similar periods found in other AGN QPOs.

Abstract

We found a possible ~ 1 hour quasi-periodic oscillation (QPO) in a ~ 55 ks X-ray observation of the narrow-line Seyfert 1 galaxy MCG--06--30--15 made with the XMM-Newton EPIC/pn detector in the energy range 0.3 -- 10 keV. We identify a total modulation of ~ 16% in the light curve and find a $\simeq$ 3670~s quasi-period using Lomb-Scargle periodogram (LSP) and weighted wavelet Z-transform (WWZ) techniques. Our analyses of eight light curves of MCG--06--30--15, indicated the possible presence of an oscillation during one of them. The LSP indicates a statistically significant ($\simeq$ 3$\sigma$) QPO detection. A WWZ analysis shows that the signal at this possible roughly 3670s period is present, and rather persistent, throughout the observation; however, a signal around 8735s is more persistent. We briefly discuss models that can produce X-ray QPOs with such periods in narrow line Seyfert 1 galaxies, as both other claimed QPO detections in this class of AGN had very similar periods.