Harmonic QPOs and Thick Accretion Disk Oscillations in BL Lac Object AO 0235+164

Abstract

Periodic outbursts are observed in many AGNs and usually explained with a supermassive black hole binary (SMBHB) scenario. However, multiple periods are observed in some AGNs and cannot be explained with it. Here we analyze the periodicity of the radio light curves of AO 0235+164 at multi-frequencies and report the discovery of six QPOs in integer ratio 1:2:3:4:5:6 of QPO frequencies, of which the second with period $P_2=(5.46\pm 0.47)\mathrm{yr}$ is the strongest. We fit the radio light curves and show that the initial phases of six QPOs have zero or $\pi$ differences relative to each other. We suggest a harmonic relationship of QPOs. The centroid frequency, relative strength, harmonic relationship and relative initial phases of QPOs are independent of radio frequency. The harmonic QPOs are likely due to the quasi-periodic injection of plasma from an oscillating accretion disk into the jet. We estimate the supermassive black hole mass $M_{\mathrm{BH}}\simeq (4.72\pm 2.04)\times 10^8{M}_{\odot }$ and the accretion rate $\dot{m}\simeq 0.007$. With the knowledge of accretion disk, it implies that the inner region of accretion disk of AO 0235+164 is a radiatively inefficient accretion flow. The oscillation accretion is due to the p-mode oscillation of the thick disk probably excited by a SMBHB. The theoretical predications of fundamental oscillation frequency and the harmonics are well consistent with the observations. Harmonic QPOs would be absent when the thick disk becomes geometrically thin due to the increase of accretion rate. We discuss the observations of AO 0235+164 basing on the SMBHB-thick disk oscillation scenario.

40 pages, 10 figures, 1 table; accepted for publication in ApJ

References in corpus (3)

• Optical Monitoring of BL Lacertae Object OJ 287: a 40-Day Period?
• X-ray emission from the blazar AO 0235+16: the XMM-Newton and Chandra point of view
• Oscillations of Thick Accretion Discs Around Black Holes

Cited by in corpus (18)

• A milliparsec supermassive black hole binary candidate in the galaxy SDSS J120136.02+300305.5
• Detection of Possible Quasi-periodic Oscillations in the Long-term Optical Light Curve of the BL Lac Object OJ 287
• Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state
• Radio and $\gamma$-ray variability in the BL Lac PKS 0219 -164: Detection of quasi-periodic oscillations in the radio light curve
• Multi-wavelength temporal and spectral variability of the blazar OJ 287 during and after the December 2015 flare: a major accretion disc contribution
• Transient Quasi-Periodic Oscillations at $\gamma$-rays in the TeV Blazar PKS 1510-089
• Tidal Disruption of Stellar Objects by Hard Supermassive Black Hole Binaries
• Supermassive binary black holes among cosmic gamma-ray sources
• Spectroscopic monitoring of the BL Lac object AO 0235+164
• Evolution of Supermassive Black Hole Binary and Acceleration of Jet Precession in Galactic Nuclei
• Absence of the predicted 2022 October outburst of OJ 287 and implications for binary SMBH scenarios
• Parsec-scale jet properties of the quasar PG 1302$-$102
• Two Transient Quasi-periodic Oscillations in $\gamma$-Ray Emission from the Blazar S4 0954+658
• A 31.3 day Transient Quasiperiodic Oscillation in Gamma-ray Emission from Blazar S5 0716+714
• Search for periodicities in High Energy AGNs with a time-domain approach
• The detection of possible $\gamma$-ray quasi-periodic modulation with $\sim$600 days from the blazar S2 0109+22
• On the origin of multifrequency temporal and spectral variability in Ton 599
• Parsec-scale jet precession and a putative supermassive binary black hole system in the blazar AO 0235+164