RoboPol: AGN polarimetric monitoring data

Blinov, D.; Kiehlmann, S.; Pavlidou, V.; Panopoulou, G. V.; Skalidis, R.; Angelakis, E.; Casadio, C.; Einoder, E. N.; Hovatta, T.; Kokolakis, K.; Kougentakis, A.; Kus, A. J.; Kylafis, N. D.; Kyritsis, E.; Lalakos, Aretaios; Liodakis, Ioannis; Maharana, S.; Makrydopoulou, E.; Mandarakas, N.; Maragkakis, G. M.; Myserlis, I.; Papadakis, I. E.; Paterakis, George; Pearson, T. J.; Ramaprakash, A. N.; Readhead, A. C. S.; Reig, P.; Słowikowska, A.; Tassis, Konstantinos; Xexakis, K.; Żejmo, M.; Zensus, J. A.

doi:10.1093/mnras/staa3777

Cited by 47 publications

(49 citation statements)

References 57 publications

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“…uary 3 and 2019 August 4. The 49 new AGN included here are members of either the Robopol optical polarization survey (Blinov et al 2021), the Fermi 2FHL catalog (Ackermann et al 2016), the LAT monitored list of flaring sources 3 , or the MOJAVE-Fermi hard spectrum gamma-ray sample (Lister et al 2018).…”

Section: Mojave Data Archivementioning

confidence: 99%

MOJAVE: XVIII. Kinematics and Inner Jet Evolution of Bright Radio-Loud Active Galaxies

Lister,

Homan,

Kellermann

et al. 2021

Preprint

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We have analyzed the parsec-scale jet kinematics of 447 bright radio-loud AGN, based on 15 GHz VLBA data obtained between 1994 August 31 and 2019 August 4. We present new total intensity and linear polarization maps obtained between 2017 January 1 to 2019 August 4 for 143 of these AGN. We tracked 1923 bright features for five or more epochs in 419 jets. A majority (60%) of the well-sampled jet features show either accelerated or non-radial motion. In 47 jets there is at least one non-accelerating feature with an unusually slow apparent speed. Most of the jets show variations of 10 • to 50 • in their inner jet position angle (PA) over time, although the overall distribution has a continuous tail out to 200 • . AGN with SEDs peaked at lower frequencies tend to have more variable PAs, with BL Lacs being less variable than quasars. The Fermi LAT gamma-ray associated AGN also tend to have more variable PAs than the non-LAT AGN in our sample. We attribute these trends to smaller viewing angles for the lower spectral peaked and LAT-associated jets. We identified 13 AGN where multiple features emerge over decade-long periods at systematically increasing or decreasing PAs. Since the ejected features do not fill the entire jet cross-section, this behavior is indicative of a precessing flow instability near the jet base. Although some jets show indications of oscillatory PA evolution, we claim no bona fide cases of periodicity since the fitted periods are comparable to the total VLBA time coverage.

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Section: Mojave Data Archivementioning

confidence: 99%

MOJAVE: XVIII. Kinematics and Inner Jet Evolution of Bright Radio-Loud Active Galaxies

Lister,

Homan,

Kellermann

et al. 2021

Preprint

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“…The spread of the reported proper motions is rather large. In our study (Blinov et al 2021a) we found that the ratios of 𝛿 for individual components can change up to a factor ∼ 5. Assuming a larger Doppler factor will only tighten the constraints on 𝐵 and 𝑓 .…”

Section: Discussionmentioning

confidence: 45%

“…A fraction of them shows rotations of the optical polarization plane that are most often accompanied by bright outbursts across the electromagnetic spec-★ E-mail: yannis.liodakis@utu.fi trum (Marscher et al 2008(Marscher et al , 2010Bottacini et al 2016;Raiteri et al 2017a;Uemura et al 2017;Blinov et al 2021b). While their optical and radio linear polarization (LP) properties have been getting plenty of attention lately (e.g., Kovalev et al 2020;Kravchenko et al 2020;Blinov et al 2021a;Event Horizon Telescope Collaboration et al 2021;Goddi et al 2021), their optical circular polarization (CP) properties are unexplored. This is partly because of the scarcity of instruments capable of delivering CP measurements, but also because CP is expected to be low even in optimistic scenarios, requiring very sensitive instruments.…”

Section: Introductionmentioning

confidence: 99%

Constraints on magnetic field and particle content in blazar jets through optical circular polarization

Liodakis,

Blinov,

Potter

et al. 2021

Preprint

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Polarization offers a unique view in the physical processes of astrophysical jets. We report on optical circular polarization observations of two famous blazars, namely 3C 279 and PKS 1510−089, at high linearly polarized states. This is the first time PKS 1510−089 is observed in optical circular polarization. While only upper limits can be extracted from our observing campaign, the non-detection of optical circular polarization allows us to provide meaningful constraints on their magnetic field strength and jet composition. We find that high-energy emission models requiring high magnetic field strength and a low positron fraction can be excluded.

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“…0059+581 has been used as a bright and compact fringe finder during VGOS commissioning work. It does however exhibit significant flux density variability on short and long timescales, and has been included in multiple monitoring campaigns at radio (Lister et al, 2018(Lister et al, , 2021, gamma-ray (Paliya et al, 2021) and optical (Blinov et al, 2021) wavelengths. This source was the one most often included in our monitoring, already from the start and our FM-results are shown in Fig.…”

Section: +581mentioning

confidence: 99%

Broad band flux-density monitoring of radio sources with the Onsala twin telescopes

Varenius,

Maio,

Bail

et al. 2022

Preprint

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Context and aims:The Onsala twin telescopes (OTT) are two 13 m telescopes located at the Onsala Space Observatory in Sweden. With dual linear polarized broad-band (3-14 GHz) receivers, they are part of the next generation Very Long Baseline Interferometry (VLBI) Global Observing System (VGOS) for geodesy and astrometry. In addition to purely geodetic data products, VGOS will regularly produce full-polarisation images of hundreds of radio sources. These rich monitoring data will be valuable for both astronomy and geodesy. In this pilot study we aim to monitor 10 bright radio sources to search for flares or similar activity, and to verify the instrument calibration on long (months) and short (hours) time scales. Method: We observed and analysed 91 short (<30 min) sessions spanning 7 months. We monitored seven potentially variable radio sources (0059+581, 0552+398, 1144+402, 1156+295, 1617+229, 3C418, OJ287) and three reference calibrators (3C147, 3C286, 3C295). We used the Common Astronomy Software Applications (CASA) package to fringe-fit, bandpass-correct and scale the data to obtain flux densities in the four standard VGOS bands: 3.0-3.5 GHz (band 1), 5.2-5.7 GHz (band 2), 6.3-6.8 GHz (band 3), and 10.2-10.7 GHz (band 4). Results: We obtain simultaneous multi-frequency light curves for ten radio sources. A bright multi-frequency flare is observed in the radio source 0059+581. OJ287 and 1156+295 show significant longterm variability. Conclusions: After correcting for instrumental biases, we determine the empirical flux density uncertainty as ∼5 %. Future refined analysis methods will allow regular monitoring of more and fainter sources.

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RoboPol: AGN polarimetric monitoring data

Cited by 47 publications

References 57 publications

MOJAVE: XVIII. Kinematics and Inner Jet Evolution of Bright Radio-Loud Active Galaxies

MOJAVE: XVIII. Kinematics and Inner Jet Evolution of Bright Radio-Loud Active Galaxies

Constraints on magnetic field and particle content in blazar jets through optical circular polarization

Broad band flux-density monitoring of radio sources with the Onsala twin telescopes

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