Possible quasi-periodic ejections in quasar B1308+326

Abstract

Context. The search for periodic features in flux variability and kinematics of superluminal components in blazars is capable of providing significant clues for the understanding of the physical processes in their central engines (black-hole/accretion-disk systems), especially concerning the formation and structure of their relativistic jets and radiation mechanisms. Aims. The jet swing on parsec-scales and the change of the ejection position angle of the superluminal components with time in the quasar B1308+326 (z = 0.997) are investigated as quasi-periodic behaviors. Methods. A previously published precessing jet nozzle model is applied to model the source kinematics and a possible jet precession period is found. Results. Based on the model fitting of the kinematics for a subset of components, it is shown that their kinematics, including the shape of the inner trajectories and the motion of the components, could be well fitted in terms of the precessing jet nozzle model and a precession period of ∼16.9 ± 0.3 yr is derived. Different precession mechanisms are discussed and compared. Conclusions. It is shown that the swing of the ejection position angle of the superluminal knots observed in B1308+326 may be due to the orbital motion of a putative supermassive black hole binary in its nucleus. Some relevant parameters of the binary model are estimated. We also discuss the spin-induced precession mechanism in the single black hole scenario and an estimate for the spin of the Kerr black hole is obtained.

Possible evidence of a supermassive black hole binary with two radio jets in blazar 3C279

“…In the following we apply the precessing jet nozzle model proposed by Qian et al (1991Qian et al ( , 2009 to model-fit the kinematics of the superluminal components observed in 3C279 during the period 1981-2015. This model has been applied to study the jet kinematics and precession in several blazars (e.g., 3C345, 3C454.3, NRAO 150, 3C279, B1308+326, PG 1302; see Qian 2011Qian , 2012Qian , 2013Qian , 2016Qian et al 2009Qian et al , 2014Qian et al , 2017Qian et al , 2018. The precessing nozzle model contains a number of assumptions: (1) superluminal components are ejected from the jet nozzle and move along the jet axis, which has a parabolic or helical pattern; (2) the jet axis precesses around a fixed precession axis with a certain period, sweeping a jet cone; (3) the innermost trajectories of the knots are assumed to follow a precessing common trajectory and their outer trajectory may deviate from the common trajectory pattern at different core separations, and trajectory curvatures should be taken into consideration; (4) the distribution of the isolated knots sequentially ejected at different times by the nozzle reveals the structure and evolution of the entire jet (jet-body) seen on VLBI maps.…”

“…Here φ represents the phase of the helical motion and A represents the amplitude. Both are functions of arc-length Geometry of the precession model, adopted and generalized from Qian et al (1991Qian et al ( , 2017Qian et al ( , 2018. Five coordinate systems are introduced.…”

“…Research on blazars is an important extragalactic astrophysical field in which extensive observations of their radiation from radio to γ rays are carried out and the mechanisms of radiation are studied (e.g., Abdo et al 2010;Begelman et al 1980;Blandford & Znajek 1977;Blandford & Payne 1982;Jorstad & Marscher 2016;Jorstad et al 2017;Chatterjee et al 2012Chatterjee et al , 2008Lewis et al 2018;Li et al 1992;Marscher et al 2017Marscher et al , 2012Marscher et al , 2010Meier et al 2001;Meier & Nakamura 2006;Petropoulou et al 2016Petropoulou et al , 2017Raiteri et al 2010;Schinzel et al 2010;Vercellone et al 2010;Vlahakis & Koenigl 2004;Qian 2013Qian , 2015Qian , 2016Qian et al 2009Qian et al , 2010Qian et al , 2014Qian et al , 2017Qian et al , 2018. These studies have led to many important results for blazar physics, especially for the various physical processes occurring in the relativistic jets and the central black hole/accretion disk systems.…”

Model simulation of jet precession in quasar PG 1302-102

“…The observational evidence largely comes from two kinds of phenomena: (i) periodicities in optical and radio light curves which are correlated in some cases; (ii) periodic variations in (compact) radio cores mapped by VLBI, which include quasi-periodic undulating jet structures (swing of jet spines) and quasi-periodic wobbling of the ejection position angle of superluminal components. Many reports may be referred for several blazars, for example, BL Lac (Raiteri 2001;Stirling et al 2003;Tateyama 2009); 3C273 (Abraham & Romero 1999;Savolainen et al 2006;Calzadilla et al 2015); PKS 0420-014 (Britzen et al 2001); B0605-085 (Kudrayavtseva et al 2011); 3C279 (Qian 2012(Qian , 2013; 3C345 (Qian et al 1991;Steffen et al 1995;Qian et al 2009); 3C454.3 (Qian et al 2007(Qian et al , 2014; OJ287 (Kikuchi et al 1988;Villata et al 1998;Tateyama & Kingham 2004;Valtonen & Wiik 2012;Valtonen & Pihajoki 2013); NRAO 150 (Agudo et al 2007;Agudo 2009;Molina et al 2014;Qian 2016); PG 1302-102 (Graham et al 2015;Kun et al 2015); B2 1308+326 (Lister et al 2013;Qian et al 2017;Britzen et al 2017;hereafter BQS17). Most recently, Calzadilla et al (2015) reported the detection of the jet precession on sub-parsec scales in the archetypal blazar 3C273 with the Event Horizon Telescope at 1.3 mm wavelength.…”

“…Their observed ejection times are ∼2005.01 ± 0.7 and ∼2007.31 ± 0.3, differing by ∼2.3 yr. If its jet swing is periodic and produced by the jet precession, then the precession period should be a bit longer than 4.6 yr (see Qian et al 2017;Britzen et al 2017 for QSO B1308+326 and below). Moreover, knot C6 and knot C1 have very similar (almost the same, see Fig.…”