Circular and linear polarization variations of compact radio sources

Komesaroff, M. M.; Roberts, Jane; Milne, D. K.; Rayner, P. T.; Cooke, David J.

doi:10.1093/mnras/208.2.409

Cited by 57 publications

(64 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies have revealed a general tendency of the circular polarization handedness to remain stable over many years (e.g., Komesaroff et al 1984;Homan & Wardle 1999;Homan et al 2001). The consistency of the circular polarization sign may indicate either a consistent underlying ordered jet Notes.…”

Section: Sources With Stable Polarizationmentioning

confidence: 90%

“…However, 3C 286, 3C 295, 3C 48 and CTA 102 show significant circular polarization ( m c /σ m c ≥ 3) at 4.85 GHz with at least one of the two correction methods. Komesaroff et al (1984) observed two of the sources presented in Table 9 between December 1976 and March 1982, namely CTA 102 and PKS 1127-14. At that time CTA 102 showed variable circular polarization degree, which suggests that its m c cannot be considered stable over such long time scales.…”

Section: Sources With Stable Polarizationmentioning

confidence: 95%

“…We compared our data set with the one presented several decades ago in Komesaroff et al (1984) to investigate the longterm stability of the circular polarization handedness, independently of the stability in the amplitude of m c . There are ten sources common to the two samples.…”

Section: Sources With Stable Polarizationmentioning

confidence: 99%

See 2 more Smart Citations

Full-Stokes polarimetry with circularly polarized feeds

Myserlis

Angelakis

Kraus

et al. 2018

A&A

View full text Add to dashboard Cite

We present an analysis pipeline that enables the recovery of reliable information for all four Stokes parameters with high accuracy. Its novelty relies on the effective treatment of the instrumental effects even before the computation of the Stokes parameters, contrary to conventionally used methods such as that based on the Müller matrix. For instance, instrumental linear polarization is corrected across the whole telescope beam and significant Stokes Q and U can be recovered even when the recorded signals are severely corrupted by instrumental effects. The accuracy we reach in terms of polarization degree is of the order of 0.1-0.2%. The polarization angles are determined with an accuracy of almost 1 • . The presented methodology was applied to recover the linear and circular polarization of around 150 active galactic nuclei, which were monitored between July 2010 and April 2016 with the Effelsberg 100-m telescope at 4.85 GHz and 8.35 GHz with a median cadence of 1.2 months. The polarized emission of the Moon was used to calibrate the polarization angle measurements. Our analysis showed a small system-induced rotation of about 1 • at both observing frequencies. Over the examined period, five sources have significant and stable linear polarization; three sources remain constantly linearly unpolarized; and a total of 11 sources have stable circular polarization degree m c , four of them with non-zero m c . We also identify eight sources that maintain a stable polarization angle. All this is provided to the community for future polarization observations reference. We finally show that our analysis method is conceptually different from those traditionally used and performs better than the Müller matrix method. Although it has been developed for a system equipped with circularly polarized feeds, it can easily be generalized to systems with linearly polarized feeds as well.

show abstract

Section: Sources With Stable Polarizationmentioning

confidence: 90%

Section: Sources With Stable Polarizationmentioning

confidence: 95%

See 1 more Smart Citation

Full-Stokes polarimetry with circularly polarized feeds

Myserlis

Angelakis

Kraus

et al. 2018

A&A

View full text Add to dashboard Cite

show abstract

“…Of course, it is possible to destroy any correlation between linear and circular polarization through either some kind of Faraday depolarization or by simply having the circular polarization produced in a region much smaller than even our VLBI beam. Komesaroff et al (1984) found that, despite reasonably large fractional variability in circularly polarized flux, changes in sign of the CP for a particular source were rare. Over their ∼ 5 year observing window, only 2 out of 14 variable CP detected sources showed clear changes in the sign of their circular polarization.…”

Section: What Have We Learned So Far?mentioning

confidence: 93%

Probing the Circular Polarization of Relativistic Jets on VLBI Scales

Homan

Wardle

2003

Astrophysics and Space Science

View full text Add to dashboard Cite

Abstract. High resolution studies of circular polarization allow us see where it arises in a jet, study its local fractional level and spectrum, and compare these results to local measures of linear polarization and Faraday rotation. Here we not only review past results from Very Long Baseline Array (VLBA) circular polarization studies, but we also present preliminary new results on two quasars. In the core of PKS 0607−157, we find strong circular polarization at 8 GHz and much weaker levels at 15 GHz. Combined with the linear polarization data, we favor a simple model where the circular is produced by Faraday conversion driven by a small amount of Faraday rotation. In the core of 3C 345, we find strong circular polarization at 15 GHz in a component with distinct linear polarization. This core component is optically thick at 8 GHz, where we detect no circular polarization. With opposite trends in frequency for PKS 0607−157 and 3C 345, it seems clear that local conditions in a jet can have a strong effect on circular polarization and need to be taken into account when studying inhomogeneous objects with multi-frequency observations.

show abstract

“…Brunthaler et al, 2001 ;Bower et al, 1999;Sault and Macquart, 1999), as well as a number of blazars (see e.g. Komesaroff et al, 1984), have exhibited a significant amount of circular polarisation (CP) apparently unassociated with any linear polarisation (LP). This has proved difficult to explain with the standard set of polarised emission mechanisms alone, often requiring specialised magnetic field or disk structures.…”

Section: Introductionmentioning

confidence: 99%

General Relativistic Magnetoionic Theory

Broderick

Blandford

2003

Astrophysics and Space Science

View full text Add to dashboard Cite

Abstract. We have developed methods for tracing rays and performing radiative transfer through a magnetoactive plasma in a general relativistic environment. The two electromagnetic plasma modes propagate differently due to a combination of dispersive and gravitational effects. We have found that, when given an appropriate environment surrounding the central black hole, it is indeed possible to generate a significant degree of circular polarisation without an appreciable amount of linear polarisation due to these effects alone.

show abstract

Circular and linear polarization variations of compact radio sources

Cited by 57 publications

References 0 publications

Full-Stokes polarimetry with circularly polarized feeds

Full-Stokes polarimetry with circularly polarized feeds

Probing the Circular Polarization of Relativistic Jets on VLBI Scales

General Relativistic Magnetoionic Theory

Contact Info

Product

Resources

About