MOJAVE – XX. Persistent linear polarization structure in parsec-scale AGN jets

Pushkarev, A. B.; Aller, H. D.; Aller, M. F.; Homan, D. C.; Kovalev, Y. Y.; Lister, M. L.; Pashchenko, I. N.; Savolainen, Tuomas; Zobnina, D. I.

doi:10.1093/mnras/stad525

Cited by 23 publications

(37 citation statements)

References 98 publications

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“…The EVPA is almost perpendicular to the direction of the jet, suggesting that a poloidal magnetic field dominates this region. This is consistent with the statistics that the spatial distribution of EVPAs in radio galaxies shows an excessive orthogonal polarization orientation based on the linear polarization properties of 436 AGNs (Pushkarev et al 2023). However, the toroidal magnetic field with an average EVPA of −40°is comparable to the poloidal field in the knot region.…”

Section: Polarizationsupporting

confidence: 89%

Detection of a ∼0.1c Radio Knot in M81* Associated with a Moderate X-Ray Flare

Wang,

Jiang,

Shen

et al. 2023

ApJ

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Through very long baseline interferometry observations of one of the closest low-luminosity active galactic nuclei, M81*, at multiple frequencies of 8.8, 22, and 44 GHz, a bright discrete knot with an unusual low apparent speed ∼0.1c was detected. Combined with the contemporaneous monitoring of X-ray data at 2–10 keV, our data indicate that a moderate X-ray flare happened when the knot was launched from the core region. Three possible origins of the knot are proposed to explain our observational results. They are an episodic jet ejection, a low-speed shock wave, and a possible secondary black hole in a binary system. Future intensive multiwavelength monitoring can help to understand the discrete knot as well as the central black hole better.

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Section: Polarizationsupporting

confidence: 89%

Detection of a ∼0.1c Radio Knot in M81* Associated with a Moderate X-Ray Flare

Wang,

Jiang,

Shen

et al. 2023

ApJ

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“…In the jet region, Pushkarev et al (2023) also found that the EVPAs in quasars tend to be preferentially transverse to the jet in the outer ridge line regions. For the jet of 1604+159, we did not detect the EVPA transverse to the jet but had a large separation of ∼ ± 40°from the jet direction, where positive and…”

Section: Linear Polarization Distributionmentioning

confidence: 76%

“…MOJAVE monitored the source 1604+159 for six epochs from 2009 to 2013 at 15 GHz (Lister et al 2018) and studied the source with stacking (Pushkarev et al 2023). Stacking has the advantage of improving the image sensitivity and providing a complete jet cross section structure as much as possible by utilizing existing data; through distributions of EVPA and fractional polarization, stacking shows long-term persistent magnetic field configuration (Pushkarev et al 2023).…”

Section: The Magnetic Field In the Jetmentioning

confidence: 99%

“…We found the fractional polarization to be higher than that in the central region. More and more evidence of an increase of fractional polarization with distance from the jet base indicates that the magnetic field becomes more ordered along the jet (Cawthorne et al 1993;Lister & Smith 2000;Lister 2001;Lister & Homan 2005;Pushkarev et al 2023), which may due to reasons including small Faraday rotation (Hovatta et al 2012) and a spectral aging effect (Kardashev 1962).…”

Section: Linear Polarization Distributionmentioning

confidence: 99%

“…Lister et al (2019) analyzed its jet speed at parsec scale and found a maximum 71 ± 14 μas y −1 (2.09 ± 0.41c) based on three moving features. Pushkarev et al (2023) and Zobnina et al (2023) have studied its evolution of linear polarization at 15 GHz spanning from 2009 to 2013. They have found that the jet of 1604+159 has a slight S shape and the polarization direction or electric vector position angle (EVPA) in general orients toward the jet direction from the VLBI core to a distance of about 4 mas from the core.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of Magnetic Field of the Quasar 1604+159 at parsec Scale

Hu,

Hong,

Zhao

et al. 2024

ApJ

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We have analyzed the total intensity, spectral index, linear polarization, and rotation measure (RM) distributions at the parsec scale for the quasar 1604+159. The source was observed at 5.0, 8.4, and 15.4 GHz in 2002 and 4.6, 5.1, 6.0, 7.8, 12.2, 15.2, and 43.9 GHz in 2020 with the American Very Long Baseline Array (VLBA). Combining the polarization results of Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments at 15 GHz from 2009 to 2013, we studied the evolution of magnetic field at the parsec scale for the source. We detected a core-jet structure. The jet extends to the distance of ∼25 mas from the core at a direction of ∼66° north by east. The shape of the jet derived from 15 GHz data varies slightly with time and could be described by a straight line. Based on the linear polarization distribution in 2002, we divided the source structure into the central region and the jet region. In the jet region, we find the polarized emission varies with time. The flatter spectral index values and electric vector position angle direction indicate the possible existence of shocks, contributing to the variation of polarization in the jet with time. In the central region, the derived core shift index k r values indicate that the core in 2002 is close to the equipartition case, while it deviated from the case in 2020. The measured magnetic field strength in 2020 is 2 orders of magnitude lower than that in 2002. We detected transverse RM gradients, evidence of a helical magnetic field, in the core. The polarized emission orients in general toward the jet direction in the core. At 15 GHz, in the place close to the jet base, the polarization direction changes significantly with time from perpendicular to parallel to the jet direction. The evolution of RM and magnetic field structure are potential reasons for the observed polarization change. The core ∣RM∣ in 2020 increases with frequency following a power law with index a = 2.7 ± 0.5, suggesting a fast electron density falloff in the medium with distance from the jet base.

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