Details

Autor(en) / Beteiligte

• Sobey, C
• Bilous, A V
• Grießmeier, J-M
• Hessels, J W T
• Karastergiou, A
• Keane, E F
• Kondratiev, V I
• Kramer, M
• Michilli, D
• Noutsos, A
• Pilia, M
• Polzin, E J
• Stappers, B W
• Tan, C M
• van Leeuwen, J
• Verbiest, J P W
• Weltevrede, P
• Heald, G
• Alves, M I R
• Carretti, E
• Enßlin, T
• Haverkorn, M
• Iacobelli, M
• Reich, W
• Van Eck, C

Titel

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

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2019-04, Vol.484 (3), p.3646-3664

Ort / Verlag

Oxford University Press

Erscheinungsjahr

2019

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• ABSTRACT 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 3D structure of the Galactic magnetic field.