J/MNRAS/484/3646 LOFAR PSR low-frequency Faraday rotation measures (Sobey+ 2019)
Low-frequency Faraday rotation measures towards pulsars using LOFAR:
probing the 3D Galactic halo magnetic field.
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., Leeuwen J.van , Verbiest J.P.W.,
Weltevrede P., Heald G., Alves M.I.R., Ensslin T.Carretti E., Haverkorn M.,
Iacobelli M., Reich W., Van Eck C.
<Mon. Not. R. Astron. Soc. 484, 3646 (2019)>
=2019MNRAS.484.3646S 2019MNRAS.484.3646S (SIMBAD/NED BibCode)
ADC_Keywords: Pulsars ; Magnetic fields
Keywords: techniques: polarimetric - pulsars: general - ISM: magnetic fields -
Galaxy: structure
Abstract:
We determined Faraday rotation measures (RMs) towards 137 pulsars in
the northern sky, using Low-Frequency Array (LOFAR) observations at
110-190MHz. 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
approximately 0.1rad/m2. 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 0.001rad/m2. 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(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.
Description:
The data in table RMcatcsv.dat presents the results of the
(ionosphere-corrected) RMs determined towards 136 pulsars, using
110-190MHz LOFAR observations taken between 2012 December to 2014
November. We determined the RMs towards 117 pulsars in the
non-recycled pulsar census (Bilous et al., 2016A&A...591A.134B 2016A&A...591A.134B) and 19
pulsars in the MSP census (Kondratiev et al., 2016A&A...585A.128K 2016A&A...585A.128K).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 142 136 Summary of RM measurements
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See also:
http://www.atnf.csiro.au/people/pulsar/psrcat : ATNF pulsar catalogue
http://astron.nl/psrcensus : processed data and supplementary materials
for LOFAR pulsar censuses
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of pulsar as in the ATNF catalogue v.1.59
12- 21 A10 --- Jname Name of pulsar as in the ATNF catalogue v.1.59
based on J2000 coordinates.
23- 29 F7.2 rad/m2 RMpsrcat ? Faraday rotation measure (RM), if available,
in the ATNF pulsar catalogue v.1.59
31- 35 F5.2 rad/m2 e_RMpsrcat ? RM uncertainty, if available, in the ATNF
pulsar catalogue v.1.59
37- 42 A6 --- r_RMpsrcat Reference code for RM, if available, in the
ATNF pulsar catalogue v.1.59
44- 54 F11.5 d MJD LOFAR observing epoch in modified Julian date
56- 59 I4 --- S/N Peak S/N of the average total intensity
(Stokes I) profile (1)
61- 62 I2 --- Nbins Number of pulse phase bins used to extract
the Stokes parameters used to measure the RMs
64- 67 I4 --- Npbins Total number of pulse phase bins across the
pulse profile
69- 77 F9.5 pc/cm3 DM Dispersion measure (1)
79- 85 F7.5 pc/cm3 e_DM Dispersion measure uncertainty
87- 93 F7.2 rad/m2 RMobs Total observed RM
95- 98 F4.2 rad/m2 e_RMobs Total observed RM uncertainty
100-103 F4.2 rad/m2 RMion Ionospheric RM contribution calculated
using ionFR (2)
105-108 F4.2 rad/m2 e_RMion Ionospheric RM uncertainty calculated
110-116 F7.2 rad/m2 RMISM RM ISM (=RMobs-RMion)
118-121 F4.2 rad/m2 e_RMISM RM ISM uncertainty
123-128 F6.3 ugauss B Electron density-weighted average magnetic
field parallel to the LoS
130-134 F5.3 ugauss e_B Electron density-weighted average magnetic
field parallel to the LoS uncertainty
136 A1 --- l_sRM Upper limit flag on sRM
137-142 F6.4 rad/m2 sRM ?=0 RM dispersion output from RM CLEAN
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Note (1): from Bilous et al., 2016A&A...591A.134B 2016A&A...591A.134B/Kondratiev et al.,
2016A&A...585A.128K 2016A&A...585A.128K.
Note (2): ionFR (Sotomayor-Beltran et al., 2013A&A...552A..58S 2013A&A...552A..58S)
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Acknowledgements:
Charlotte Sobey, Charlotte.Sobey(at)csiro.au
(End) Patricia Vannier [CDS] 26-Feb-2019