Parsec-scale jet properties of the quasar PG 1302−102

Abstract

The quasar PG 1302−102 is believed to harbour a supermassive binary black hole (SMBBH) system. Using the available 15 GHz and 2 − 8 GHz, multi-epoch Very Long Baseline Array data, we constrain the pc-scale jet properties based on the inferred mean proper motion, including a bulk Lorentz factor 5.1 ± 0.8, jet inclination angle 11.• 4 ± 1.• 7, projected position angle = 31.• 8, intrinsic half opening angle 0.• 9 ± 0.• 1 and a mean 2 − 8 GHz spectral index of 0.31. A general relativistic helical jet model is presented and applied to predict quasi-periodic oscillations of ∼ 10 days, power law power spectrum shape and a contribution of up to ∼ 53 percent to the observed variable core flux density. The model is used to make a case for high resolution, moderately sampled, long duration radio interferometric observations to reveal signatures due to helical knots and distinguish them from those due to SMBBH orbital activity including a phase difference ∼ π and an amplitude ratio (helical light curve amplitude/SMBBH light curve amplitude) of 0.2 − 3.3. The prescription can be used to identify helical kinematic signatures from quasars, providing possible candidates for further studies with polarization measurements. It can also be used to infer promising SMBBH candidates for the study of gravitational waves if there are systematic deviations from helical signatures.

The quest for dual and binary supermassive black holes: A multi-messenger view

“…However, in cases where multiple indications are available, the precessing jet model could constrain the SMBH masses, separation and orbital period. Jet studies are often invoked for tight binary candidates that are radio sources but not directly resolvable with interferometers, to seek indirect supportive evidence for binarity (Kun et al, 2015;Mohan et al, 2016;Mooley et al, 2018). These targets are selected e.g., on the basis of their periodic optical variability; this will be discussed in detail in Sect.…”

Multi-messenger Time-domain Signatures Of Supermassive Black Hole Binaries

“…Additionally, as mentioned above, if the periodicity is due to periodic accretion, the variability may contain multiple periodic components with a characteristic frequency pattern (Charisi et al 2015;D'Orazio et al 2015a). The signature of the binary may also be imprinted on the IR emission from the dust in the AGN (Jun et al 2015;D'Orazio & Haiman 2017), in the X-ray spectrum of the source (Saade et al 2020) and on the radio jets (Kun et al 2015;Mohan et al 2016). A subset of the candidates show one or more of the above promising signatures.…”

VLBI Studies of DAGN and SMBHB Hosting Galaxies

“…Based on optical periodic variability over a timescale of ∼5 years, the source PG 1302−102 was proposed as a SMBHB candidate (Graham, Djorgovski, Stern, Glikman, et al, 2015). In addition to multiwavelength periodicity (D'Orazio et al, 2015), PG 1302−102 exhibits interesting parsec-scale jet structure, with Kun et al (2015) and Mohan et al (2016) exploring its helical nature and Qian et al (2018) applying a model of a precessing jet nozzle to infer the association between the parsec-scale radio jet and the optical variability timescale.…”

“…Updated lists of inferred DAGN compiled from the literature are presented in Rubinur et al () and Das et al (). The continuum or line‐based optical light curves may indicate quasiperiodicity over timescales of a few to tens of years, possibly related to the orbital period of a Keplerian SMBHB (e.g., Charisi et al, ; Graham, Djorgovski, Stern, Drake, et al, ; Mohan et al, ). The well‐studied AGN OJ 287 putatively hosts a SMBHB, inferred through a pair of periodic optical outbursts every ∼12 years (e.g., Sillanpaa et al, ; Valtonen et al, ) resulting from the impinging of the accretion disk of the primary by the secondary SMBH at these intervals during its orbital motion (e.g., Lehto & Valtonen, ).…”