An X-Ray Periodicity of ∼1.8 hr in Narrow-line Seyfert 1 Galaxy Mrk 766

Abstract

In the narrow-line Seyfert 1 galaxy Mrk 766, a Quasi-Periodic Oscillation (QPO) signal with a period of ∼ 6450 s is detected in the XMM-Newton data collected on 2005 May 31. This QPO signal is highly statistical significant at the confidence level at ∼ 5σ with the quality factor of Q = f /∆f > 13.6. The X-ray intensity changed by a factor of 3 with root mean square fractional variability of 14.3%. Furthermore, this QPO signal presents in the data of all three EPIC detectors and two RGS cameras and its frequency follows the f QPO -M BH relation spanning from stellar-mass to supermassive black holes. Interestingly, a possible QPO signal with a period of ∼ 4200 s had been reported in the literature. The frequency ratio of these two QPO signals is ∼ 3:2. Our result is also in support of the hypothesis that the QPO signals can be just transient. The spectral analysis reveals that the contribution of the soft excess component below ∼ 1 keV is different between epochs with and without QPO, this property as well as the former frequency-ratio are well detected in X-ray BH binaries, which may have shed some lights on the physical origin of our event.

Possible ∼0.4 h X-ray quasi-periodicity from an ultrasoft active galactic nucleus

“…Timing studies of XRBs have suggested that QPOs can evolve with time in their amplitudes or frequencies, or both (Remillard & McClintock 2006). Such a time dependence has also been found in AGNs where the QPO signal is only seen in segment of light curves (e.g., Gierliński et al 2008b;Pan et al 2016;Zhang et al 2017). Weighted Wavelet Z-transform (WWZ) is a powerful technique for analyzing and measuring non-stationary periodic features of the time series by performing signal decompositions in both frequency and time spaces simultaneously (Foster 1996;Czerny et al 2010).…”

“…However, a systematic study of power spectra of 104 AGNs by González-Martín & Vaughan (2012) resulted in no conclusive detections of QPOs, except for RE J1034+36. Possible detections of QPOs ( f QPO ∼ [0.7 − 2.7] × 10 −4 Hz) were reported in a few other AGNs from dedicated searches, including 2XMM J123103.2+110648 (J1231, Lin et al 2013), MS2254.9-3712 (Alston et al 2015), 1H 0707-495 (Pan et al 2016;Zhang et al 2018), Mrk 766 (Zhang et al 2017), and MCG -6-30-15 (Gupta et al 2018). In addition, QPOs were also detected in the stellar tidal disruption events (TDEs) by SMBHs where transient accretion is triggered (Reis et al 2012;Pasham et al 2019).…”

Exploring the spectral variability of the Seyfert 1.5 galaxy Markarian 530 with Suzaku

“…Periodic behaviour, though commonly detected in X-ray binaries, is something of a rarity for AGN (Zhang et al 2018) with only a handful of objects exhibiting evidence of periodicity in the X-ray. Some examples include RE J1034+396 (Gierliński et al 2008), 1H 0707−495 (Pan et al 2016), Mrk 766 (Zhang et al 2017), andNGC 3516 (Iwasawa et al 2004). Power spectrum analyses of these sources revealed periodic variability in a narrow band simultaneous with broadband variability, with the exception of NGC 3516 which exhibited only a few periods of sinusoid-like behaviour in the light curve.…”

Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance

“…Indeed, the first AGN X-ray QPO was discovered in the NLS1 RE J1034+396 with a period of 3730 ± 60 s (Gierliński et al 2008). Since then a few X-ray QPOs with lower significances have been reported in NLS1s, such as 1H 0707−495 (Pan et al 2016;Zhang et al 2018), MS 2254.9−3712 (Alston et al 2015), Mrk 766 (Zhang et al 2017), (Gupta et al 2018). A couple of Seyfert 2s were also reported to exhibit a QPO, including 2XMM J123103.2+110648 (Lin et al 2013) and XMMU J134736+173403 (Carpano & Jin 2018).…”