Optical polarization properties of AGNs with significant VLBI–<i>Gaia</i> offsets

Kovalev, Y. Y.; Zobnina, D. I.; Plavin, A. V.; Blinov, D.

doi:10.1093/mnrasl/slaa008

Cited by 28 publications

(30 citation statements)

References 34 publications

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“…Inserting into Equation (3) the expression for θ (5), in which θ 0 and ϕ max, min are given by Formulae (12) and (11), correspondingly, and solving Equation (13) with respect to θ 0 , substituting the observed flux densities of the 12-year peaks and minima between them, we obtained…”

Section: Helical Jet Precessionmentioning

confidence: 99%

Is OJ 287 a Single Supermassive Black Hole?

Butuzova

Pushkarev

2020

Universe

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Light curves for more than century optical photometric observations of the blazar OJ 287 reveals strong flares with a quasi-period of about 12 years. For a long time, this period has been interpreted by processes in a binary black hole system. We propose an alternative explanation for this period, which is based on Doppler factor periodic variations of the emitting region caused by jet helicity. Using multi-epoch very large baseline interferometry (VLBI) observations carried out in a framework of the MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) program and other VLBA (Very Long Baseline Array) archival experiments at the observing frequency of 15 GHz, we derived geometrical parameters of the jet helix. To reach an agreement between the VLBI and photometric optical observation data, the jet component motion at a small angle to the radial direction is necessary. Such non-radial motion is observed and, together with the jet helical shape, can be naturally explained by the development of the Kelvin–Helmholtz instability in the parsec-scale outflow. In this case, the true precession of the OJ 287 jet may manifest itself in differences between the peak flux values of the 12-year optical flares. A possibility to create this precession due to Lense–Thirring effect of a single supermassive black hole is also discussed.

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Section: Helical Jet Precessionmentioning

confidence: 99%

Is OJ 287 a Single Supermassive Black Hole?

Butuzova

Pushkarev

2020

Universe

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“…By deselecting objects mostly based on the optical properties, Makarov et al (2019) still found that 20% of the sources had normalized arc lengths >3. The factors causing these position differences between A&A 647, A189 (2021) optical and radio are still uncertain, even though there are a variety of possible astrophysical explanations (Makarov et al 2019;Plavin et al 2019a;Kovalev et al 2020). For instance, Kovalev et al (2017) and Petrov et al (2019) suggested that the main cause of the position differences is optical structure, the optical jets at milliarcsecond scales.…”

Section: Introductionmentioning

confidence: 99%

Evidence of theGaia–VLBI position differences being related to radio source structure

Mei-ling

Lunz

Anderson

et al. 2021

A&A

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Context. We report the relationship between the Gaia–VLBI position differences and the magnitudes of source structure effects in VLBI observations. Aims. Because the Gaia–VLBI position differences are statistically significant for a considerable number of common sources, we discuss and attempt to explain these position differences based on VLBI observations and available source images at centimeter wavelengths. Methods. Based on the derived closure amplitude root mean square (CARMS), which quantifies the magnitudes of source structure effects in the VLBI observations used for building the third realization of the International Celestial Reference Frame, the arc lengths and normalized arc lengths of the position differences are examined in detail. The radio-jet directions and the directions of the Gaia–VLBI position differences are investigated for a small sample of sources. Results. Both the arc lengths and normalized arc lengths of the Gaia and VLBI positions are found to increase with the CARMS values. The majority of the sources with statistically significant position differences are associated with the sources having extended structure. Radio source structure is the one of the major factors of these position differences, and it can be the dominant factor for a number of sources. The vectors of the Gaia and VLBI position differences are parallel to the radio-jet directions, which is confirmed via stronger evidence.

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“…In several sources (0119+115, 0346+800, 0749+540, 0859+470, 1157−215, 1652+398, 1742−078, and 2223−052), the optical centroid is close to a radio jet feature (a particularity also recently supported by Xu et al 2021), suggesting that in such sources the optical emission is dominated by optically thin jet features in the downstream region of the jet. Such regions of synchrotron emission are expected to have a more organized magnetic field and higher linear polarization (e.g., Ginzburg 1979), which is supported by observations in radio Lister & Homan (2005) and optical Kovalev et al (2020). More comments on the above-cited sources are reported in Appendix B.…”

Section: Analysis and Resultsmentioning

confidence: 63%

Parsec-scale alignments of radio-optical offsets with jets in AGNs from multifrequency geodetic VLBI, Gaia EDR3, and the MOJAVE program

Lambert

Liu

Arias

et al. 2021

A&A

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Aims. We aim to study the relative positions of quasar emission centers at different wavelengths in order to help link the various realizations of the International Celestial Reference System (ICRS), and to unveil systematic uncertainties and individual source behavior at different wavelengths. Methods. We based our study on four catalogs representing the ICRS, the ICRF3 positions in the three VLBI bands X, K, and Ka, and the Gaia EDR3 catalog in optical wavelengths. We complemented radio source positions with jet kinematics results from the MOJAVE team, allowing us to obtain jet directions on the sky. A six-parameter deformation model was used to remove systematic uncertainties present in the different catalogs. Results. For a set of 194 objects common to the four catalogs and to the objects whose jet kinematics was studied by the MOJAVE team, we computed the orientation between positions at the different wavelengths and with respect to the directions of the jets. We find that the majority of these objects have their radio-to-optical vector along the jet, with the optical centroid downstream from the radio centroids, and that the K and Ka centroids are preferably upstream in the jet with respect to the X centroid, which is consistent with the paradigm of a simple core–jet model. For a population of multiwavelength positions aligned along the jet, astrometric information can therefore be used to measure the direction of the jet independently of imaging. In addition, we find several sources for which the optical centroid coincides with stationary radio features with a relatively high fraction of polarization, indicating optical emission dominated by a synchrotron process in the jet.

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Optical polarization properties of AGNs with significant VLBI–Gaia offsets

Cited by 28 publications

References 34 publications

Is OJ 287 a Single Supermassive Black Hole?

Is OJ 287 a Single Supermassive Black Hole?

Evidence of theGaia–VLBI position differences being related to radio source structure

Parsec-scale alignments of radio-optical offsets with jets in AGNs from multifrequency geodetic VLBI, Gaia EDR3, and the MOJAVE program

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