scholarly journals Changes in Polarization Position Angle across the Eclipse in the Double Pulsar System

2012 ◽  
Vol 8 (S291) ◽  
pp. 580-582
Author(s):  
R. Yuen ◽  
R. N. Manchester ◽  
M. Burgay ◽  
F. Camilo ◽  
M. Kramer ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Faraday Rotation ◽  
Position Angle ◽  
Charge Densities

AbstractWe investigate the changes in polarization position angle in radiation from pulsar A around the eclipse in the Double Pulsar system PSR J0737-3039A/B at the 20 cm and 50 cm wavelengths using the Parkes 64-m radio telescope. The changes are ~ 2σ during and shortly after the eclipse at 20 cm but less significant at 50 cm. We show that the changes in position angle during the eclipse can be modelled by differential synchrotron absorption in the eclipse regions. Position angle changes after the eclipse are interpreted as Faraday rotation in the magnetotail of pulsar B. Implied charge densities are consistent with the Goldreich-Julian density, suggesting that the particle energies in the magnetotail are mildly relativistic.

scholarly journals 3C 216: Is It the CSS Source with the Highest Rotation Measure?

1998 ◽  
Vol 164 ◽  
pp. 183-184
Author(s):  
E. Lüdke ◽  
W. D. Cotton ◽  
H. S. Sanghera ◽  
D. Dallacasa
Keyword(s):  
Faraday Rotation ◽  
Position Angle ◽  
Angle Variation ◽  
Strong Polarization ◽  
Self Calibration ◽  
Rotation Measure ◽  
5 Ghz ◽  
Starting Model

AbstractWe discuss our VLBA observations at 5 and 2.7 GHz and our MERLIN observations at 1.6 and 5 GHz. A MERLIN+VLBA image provided good starting model for self-calibration and we obtained an unprecedent image of the bent jet of 3C 216. Our observations suggest the detection of strong polarization position angle variation across the observing band. If this is due to Faraday rotation then 3C216 may have a four-figure observed rotation measure, which is unlikely to be due to errors in the polarization position angle calibration.

scholarly journals Rotation Measure variations for millisecond pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 568-570
Author(s):  
Wenming Yan ◽  
R. N. Manchester ◽  
Na Wang
Keyword(s):  
Radio Telescope ◽  
Position Angle ◽  
Polarization Mode ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
Rotation Measure ◽  
The Mean ◽  
Pulsar Timing Array

AbstractAs part of the Parkes Pulsar Timing Array (PPTA) project, frequent observations of 20 millisecond pulsars are made using the Parkes 64-m radio telescope. Variations in the mean position angle of the 20 millisecond pulsars can be studied by the PPTA data being recorded in full-polarization mode. We briefly discuss these results.

scholarly journals Faraday Rotation of the Crab Pulsar Radiation

1971 ◽  
Vol 46 ◽  
pp. 118-118
Author(s):  
R. N. Manchester
Keyword(s):  
Faraday Rotation ◽  
Radio Astronomy ◽  
Crab Nebula ◽  
Position Angle ◽  
Crab Pulsar ◽  
Astronomy Observatory ◽  
Pulsar Radiation ◽  
Rotation Measure ◽  
The Mean ◽  
The Crab Nebula

During April, 1970, the 300-ft telescope of the National Radio Astronomy Observatory was used to determine the mean polarisation of the Crab Nebula pulsar radiation at several frequencies around 400 MHz. The position angle of the highly polarised precursor measured at each frequency, corrected for ionospheric Faraday rotation and plotted against inverse frequency squared is shown in Figure 1. The observed variation of the position angle with frequency is consistent with Faraday rotation of the plane of polarisation with a rotation measure of −40.5 ± 4.5 rad/m2. This value is of the same sign but larger than the rotation measure for the nebular radiation in the vicinity of the pulsar.

scholarly journals Radio Polarimetry of Tycho's SNR

1990 ◽  
Vol 140 ◽  
pp. 76-78
Author(s):  
John R. Dickel ◽  
Wil J. M. Van Breugel ◽  
Richard G. Strom
Keyword(s):  
Faraday Rotation ◽  
Signal To Noise Ratio ◽  
Position Angle ◽  
Signal To Noise ◽  
Significant Information ◽  
Polarized Emission ◽  
Noise Ratio ◽  
Few Data ◽  
Faraday Effects ◽  
Tycho’S Snr

The remnant of Tycho's supernova of 1572 has been polarimetrically imaged using the 4 configurations of the VLA at wavelengths of 22 and 6 cm. A few data were also obtained at wavelengths of 21, 19, and 18 cm in the B configuration to check for any ambiguities in the Faraday rotation measurements and to look for deviations from the λ2 dependence of the Faraday rotation which would indicate significant internal Faraday effects. Although the total intensity shows structure on a scale of about 1 arcsecond the polarized emission appears to be resolved into cells of perhaps 10-arcsec size (1 arcsec corresponds to 0.011 pc at the 2.2 kpc distance to Tycho's SNR). We have therefore convolved the map shown in Figure 1 to a resolution of 4 arcsec to improve the signal-to-noise ratio. The contours represent the total intensity at 6-cm wavelength and the vectors show the position angle of the magnetic field with a length corresponding to the polarized intensity at 6 cm. In order to be seen, the vectors have a separation of 6 arcsec but no significant information is lost on this spacing.

scholarly journals Linear Polarization Properties of Pulsars at 35 & 327 MHz

2000 ◽  
Vol 177 ◽  
pp. 245-246
Author(s):  
Ashish Asgekar ◽  
A. A. Deshpande
Keyword(s):  
Fourier Analysis ◽  
Radio Telescope ◽  
Faraday Rotation ◽  
Linear Polarization ◽  
Broad Band ◽  
Spectral Domain ◽  
Spectral Modulation ◽  
Polarization Characteristics

Faraday Rotation of the plane of polarization of broad-band signals, during propagation through the intervening medium, manifests as quasi-sinusoidal spectral modulations when observed with a telescope sensitive to a single linear polarization. Such a modulation can be exploited to study linear polarization characteristics of pulsars (Suleimanova, Volodin, & Shitov, 1988; Smirnova & Boriakoff 1997, Ramkumar & Deshpande 1999 (RD99)). We have used our data on a few bright pulsars at 35 MHz (Asgekar & Deshpande 1999, elsewhere in this volume) and data obtained at 327 MHz using Ooty Radio Telescope (see RD99 for details), to study average linear polarization properties using this technique. The data obtained over 256 frequency channels were re-sampled in the spectral domain to make the Faraday modulation appear periodic, and then a simple Fourier analysis was performed to look for (ACF) features associated with the possible spectral modulation (see RD99 for the analysis details).

scholarly journals Simultaneous Five Color (Ubvri) Polarimetry of EF Eri

1987 ◽  
Vol 93 ◽  
pp. 197-201 ◽  
Author(s):  
V. Piirola ◽  
A. Reiz ◽  
G.V. Coyne
Keyword(s):  
Faraday Rotation ◽  
Position Angle ◽  
Photometric Data ◽  
Phase Dependence ◽  
Type Object ◽  
Different Parts ◽  
Polarized Radiation

AbstractWe present the first observations of the AM Her type object EF Eri where both the polarization and the photometric data are recorded simultaneously in five color bands (UBVRI). The position angle rotates strongly (~30° ) vs. wavelength from U to 1, probably due to Faraday rotation or due to fact that the polarized radiation seen in the different wavelength bands comes from different parts of the accretion region. The phase dependence of the position angle requires field and accretion geometry more complicated than a simple centered dipole and a second emitting region producing weaker intermediate pulses in the infrared seems to be present. We derive the value of the inclination of the system i = 55° ± 5° , the colatitude of the active pole βl = 38° ± 5° i and the second emitting region β2 = 115° ± 5° , both of which are nearly at the same longitude facing the main accretion stream.

scholarly journals Polarization of Pulsars

1971 ◽  
Vol 46 ◽  
pp. 195-199
Author(s):  
Alan T. Moffet
Keyword(s):  
Magnetic Field ◽  
Magnetic Dipole ◽  
Faraday Rotation ◽  
Linear Polarization ◽  
Polarization Characteristic ◽  
Position Angle ◽  
Dipole Model ◽  
Yield Values ◽  
Dispersion Measures ◽  
The Magnetic Field

A survey is given of the polarization properties of pulsars. Many pulsars, although showing pulse-to-pulse variations in polarization, have a stable mean polarization characteristic. Several pulsars like 0833-45 show changes in the position angle of linear polarization across the pulse which can be interpreted as due to the changing direction of the magnetic field as envisaged in the oblique magnetic dipole model of pulsars. Faraday rotation measurements when taken with dispersion measures yield values for the interstellar magnetic field of several microgauss.

scholarly journals Magnetic field at a jet base: extreme Faraday rotation in 3C 273 revealed by ALMA

2019 ◽  
Vol 623 ◽  
pp. A111 ◽  
Author(s):  
T. Hovatta ◽  
S. O’Sullivan ◽  
I. Martí-Vidal ◽  
T. Savolainen ◽  
A. Tchekhovskoy
Keyword(s):  
Magnetic Field ◽  
Faraday Rotation ◽  
Position Angle ◽  
High Angular Resolution ◽  
Systematic Uncertainties ◽  
Rotation Measure ◽  
Linearly Polarized ◽  
Polarization Fraction ◽  
The Magnetic Field ◽  
Quasar 3C 273

Aims. We studied the polarization behavior of the quasar 3C 273 over the 1 mm wavelength band at ALMA with a total bandwidth of 7.5 GHz across 223–243 GHz at 0.8′′ resolution, corresponding to 2.1 kpc at the distance of 3C 273. With these observations we were able to probe the optically thin polarized emission close to the jet base, and constrain the magnetic field structure. Methods. We computed the Faraday rotation measure using simple linear fitting and Faraday rotation measure synthesis. In addition, we modeled the broadband behavior of the fractional Stokes Q and U parameters (qu-fitting). The systematic uncertainties in the polarization observations at ALMA were assessed through Monte Carlo simulations. Results. We find the unresolved core of 3C 273 to be 1.8% linearly polarized. We detect a very high rotation measure (RM) of (5.0 ± 0.3) × 105 rad m−2 over the 1 mm band when assuming a single polarized component and an external RM screen. This results in a rotation of >40° of the intrinsic electric vector position angle, which is significantly higher than typically assumed for millimeter wavelengths. The polarization fraction increases as a function of wavelength, which according to our qu-fitting could be due to multiple polarized components of different Faraday depth within our beam or to internal Faraday rotation. With our limited wavelength coverage we cannot distinguish between the cases, and additional multifrequency and high angular resolution observations are needed to determine the location and structure of the magnetic field of the Faraday active region. Comparing our RM estimate with values obtained at lower frequencies, the RM increases as a function of observing frequency, following a power law with an index of 2.0 ± 0.2, consistent with a sheath surrounding a conically expanding jet. We also detect ~0.2% circular polarization, although further observations are needed to confirm this result.

scholarly journals Faraday rotation effects for diagnosing magnetism in bubble environments

2014 ◽  
Vol 1 ◽  
pp. 1-5 ◽  
Author(s):  
R. Ignace
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Faraday Rotation ◽  
Faraday Effect ◽  
Polarized Light ◽  
Position Angle ◽  
Toroidal Magnetic Field ◽  
Line Of Sight ◽  
Linearly Polarized ◽  
The Magnetic Field

Abstract. Faraday rotation is a process by which the position angle (PA) of background linearly polarized light is rotated when passing through an ionized and magnetized medium. The effect is sensitive to the line-of-sight magnetic field in conjunction with the electron density. This contribution highlights diagnostic possibilities of inferring the magnetic field (or absence thereof) in and around wind-blown bubbles from the Faraday effect. Three cases are described as illustrations: a stellar toroidal magnetic field, a shocked interstellar magnetic field, and an interstellar magnetic field within an ionized bubble.

Interpretation of the Filament Depression at Millimetric and Centimetric Wavelengths

1979 ◽  
Vol 44 ◽  
pp. 131-134
Author(s):  
A. Raoult ◽  
P. Lantos ◽  
E. Fürst
Keyword(s):  
Radio Telescope ◽  
Active Regions ◽  
Simple Shape ◽  
Quiet Sun ◽  
Unstable Process

The depressions at centimetric and millimetric wavelengths associated with the filaments are studied using already published maps as well as unpublished observations from the Effelsberg 100 m radio telescope of the M.P.I., Bonn. The study has been restricted to large Ha quiescent prominences of relatively simple shape, situated far from the limb and from active regions. The data has been reduced employing one method whose main characteristics are choice of a local quiet sun definition and avoidance of the unstable process of deconvolution.

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