The Faraday rotation in the pulsar magnetosphere

Wang, Chen; Han, J. L.; Lai, Dong

doi:10.1111/j.1365-2966.2011.19333.x

Cited by 28 publications

(19 citation statements)

References 23 publications

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“…Pulsars are not expected to be Faraday-resolved (-thick) sources because they are point sources and their magnetospheric emission is not expected to impart Faraday rotation, in particular with the usual wavelength squared dependency, due to the relativistic electronpositron pair plasma expected in their magnetospheres (e.g. Wang et al 2011). The degree of polarisation emitted often increases towards lower frequencies (e.g.…”

Section: Determining Rms Using Rm-synthesismentioning

confidence: 99%

Low-frequency Faraday rotation measures towards pulsars using LOFAR: probing the 3D Galactic halo magnetic field

Sobey

Bilous

Grießmeier

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We determined Faraday rotation measures (RMs) towards 137 pulsars in the northern sky, using Low-Frequency Array (LOFAR) observations at 110-190 MHz. This low-frequency RM catalogue, the largest to date, improves the precision of existing RM measurements on average by a factor of 20 -due to the low frequency and wide bandwidth of the data, aided by the RM synthesis method. We report RMs towards 25 pulsars for the first time. The RMs were corrected for ionospheric Faraday rotation to increase the accuracy of our catalogue to ≈0.1 rad m −2 . The ionospheric RM correction is currently the largest contributor to the measurement uncertainty. In addition, we find that the Faraday dispersion functions towards pulsars are extremely Faraday thin -mostly less than 0.001 rad m −2 . We use these new precise RM measurements (in combination with existing RMs, dispersion measures, and distance estimates) to estimate the scale height of the Galactic halo magnetic field: 2.0±0.3 kpc for Galactic quadrants I and II above and below the Galactic plane (we also evaluate the scale height for these regions individually). Overall, our initial low-frequency catalogue provides valuable information about the 3-D structure of the Galactic magnetic field.

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Section: Determining Rms Using Rm-synthesismentioning

confidence: 99%

Low-frequency Faraday rotation measures towards pulsars using LOFAR: probing the 3D Galactic halo magnetic field

Sobey

Bilous

Grießmeier

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Another technique is therefore required in order to estimate the foreground Galactic contribution to the Faraday Rotation. The use of pulsars as Galactic magnetic field probes is viable as the Faraday rotation from a pulsar magnetosphere is expected to be negligible and to not exhibit significant variations (Wang, Han, & Lai 2011). Pulsars therefore provide a very clean RM signal, which measures the Galactic magnetic field, and which is not contaminated by strong intrinsic variations.…”

Section: Foreground Rotation Measurementioning

confidence: 99%

Interacting large-scale magnetic fields and ionized gas in the W50/SS433 system

Farnes

Gaensler

Purcell

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The W50/SS433 system is an unusual Galactic outflow-driven object of debatable origin. We have used the Australia Telescope Compact Array (ATCA) to observe a new 198 pointing mosaic, covering 3 • × 2 • , and present the highest-sensitivity full-Stokes data of W50 to date using wide-field, wide-band imaging over a 2 GHz bandwidth centred at 2.1 GHz. We also present a complementary Hα mosaic created using the Isaac Newton Telescope Photometric Hα Survey of the Northern Galactic Plane (IPHAS). The magnetic structure of W50 is found to be consistent with the prevailing hypothesis that the nebula is a reanimated shell-like supernova remnant (SNR), that has been re-energised by the jets from SS433. We observe strong depolarization effects that correlate with diffuse Hα emission, likely due to spatiallyvarying Faraday rotation measure (RM) fluctuations of ≥ 48 to 61 rad m −2 on scales ≤ 4.5 to 6 pc. We also report the discovery of numerous, faint, Hα filaments that are unambiguously associated with the central region of W50. These thin filaments are suggestive of a SNR's shock emission, and almost all have a radio counterpart. Furthermore, an RM-gradient is detected across the central region of W50, which we interpret as a loop magnetic field with a symmetry axis offset by ≈90 • to the east-west jet-alignment axis, and implying that the evolutionary processes of both the jets and the SNR must be coupled. A separate RM-gradient is associated with the termination shock in the Eastern ear, which we interpret as a ring-like field located where the shock of the jet interacts with the circumstellar medium. Future optical observations will be able to use the new Hα filaments to probe the kinematics of the shell of W50, potentially allowing for a definitive experiment on W50's formation history.

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“…Apart from papers where the level r = r esc at which the transition from the geometrical optics approximation to the vacuum occurs was only estimated (see e.g. Cheng & Ruderman 1979;Barnard 1986), one can note only a few papers by Petrova & Lyubarskii (2000) (these authors considered the problem in the infinite magnetic field) and by Petrova (2001Petrova ( , 2003Petrova ( , 2006, as well as the recent papers by Wang et al (2010Wang et al ( , 2011.…”

mentioning

confidence: 99%

On the mean profiles of radio pulsars - I. Theory of propagation effects

Бескин¹,

Philippov

2012

Monthly Notices of the Royal Astronomical Society

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We study the influence of propagation effects on the mean profiles of radio pulsars using the method of wave propagation in inhomogeneous media described by Kravtsov & Orlov. This approach allows us first to take into consideration the transition from geometrical optics to vacuum propagation, the cyclotron absorption and the wave refraction simultaneously. In addition, the non‐dipole magnetic field configuration, the drift motion of plasma particles and their realistic energy distribution are taken into account. It is confirmed that, for ordinary pulsars (period P ∼ 1 s, surface magnetic field B0 ∼ 1012 G) and typical plasma generation near the magnetic poles (multiplicity parameter λ = ne/nGJ ∼ 103), the polarization is formed inside the light cylinder at a distance resc ∼ 1000 R from the neutron star, the circular polarization being 5–20 per cent which is in agreement with observational data. A one‐to‐one correspondence between the signs of circular polarization and position angle (PA) derivative along the profile for both ordinary and extraordinary waves is predicted. Using numerical integration we now can model the mean profiles of radio pulsars. It is shown that the standard S‐shape form of the PA swing can be realized for small enough multiplicity λ and large enough bulk Lorentz factor γ only. It is also shown that the value of the maximum derivative of PA, which is often used for determination of the angle between magnetic dipole and rotation axis, depends on the plasma parameters and could differ from the rotation vector model (RVM) prediction.

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The Faraday rotation in the pulsar magnetosphere

Cited by 28 publications

References 23 publications

Low-frequency Faraday rotation measures towards pulsars using LOFAR: probing the 3D Galactic halo magnetic field

Low-frequency Faraday rotation measures towards pulsars using LOFAR: probing the 3D Galactic halo magnetic field

Interacting large-scale magnetic fields and ionized gas in the W50/SS433 system

On the mean profiles of radio pulsars - I. Theory of propagation effects

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