Quasi periodic oscillations in active galactic nuclei

Abstract

Quasi-periodic oscillations (QPOs) are coherent peaks of variability power observed in the X-ray power spectra (PSDs) of stellar mass X-ray binaries (XRBs). A scale invariance of the accretion process implies they should be present in the active galactic nuclei. The first robust detection was a $\sim 1$ hr periodicity in the Seyfert galaxy RE J1034+396 from a $\sim 90$ ks XMM-Newton observation, however, subsequent observations failed to detect the QPO in the $0.3-10.0$ keV band. In this talk we present the recent detection of the $\sim 1$ hr periodicity in the $1.0-4.0$ keV band of 4 further low-flux/spectrally-harder observations of RE J1034+396 (see Alston et al 2014). We also present recent work on the discovery of a QPO in the Seyfert galaxy, MS 22549-3712, which again is only detected in energy bands associated with the primary power-law continuum emission (Alston et al 2015). We conclude these features are most likely analogous to the high-frequency QPOs observed in XRBs. In both sources, we also see evidence for X-ray reverberation at the QPO frequency, where soft X-ray bands and Iron K$\alpha$ emission lag the primary X-ray continuum. These time delays may provide another diagnostic for understanding the underlying QPO mechanism observed in accreting black holes.

Proceedings for The Extremes of Black Hole Accretion, Madrid, 2015. To appear in Astronomische Nachrichten, 6 pages, 4 figures

References in corpus (10)

• X-ray Properties of Black-Hole Binaries
• X-ray reverberation around accreting black holes
• Discovery of a ~2 hr high frequency X-ray QPO and iron K alpha reverberation in the active galaxy MS 2254.9-3712
• Iron K and Compton hump reverberation in SWIFT J2127.4+5654 and NGC 1365 revealed by NuSTAR and XMM-Newton
• Detection of a QPO in 5 XMM-Newton observations of RE J1034+396
• Observations of MCG-5-23-16 with Suzaku, XMM-Newton and NuSTAR: Disk tomography and Compton hump reverberation
• Revealing the X-ray Variability of AGN with Principal Component Analysis
• X-ray time delays in the Narrow Line Seyfert 1 galaxy PG 1244+026
• Principal Component Analysis of MCG--6-30-15 with XMM-Newton
• Tracking the Evolution of QPO in RE J1034+396 Using the Hilbert-Huang Transform

Cited by in corpus (4)

• The INTEGRAL view on Black Hole X-ray Binaries
• Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1
• Probing black-hole accretion through time variability
• A Pacemaker with P=2.48 hour Modulated the Generator of Flares in the X-ray Light Curve of Sgr A* in the year 2012