A Search for Neutron Star Precession and Interstellar Magnetic Field Variations Via Multiepoch Pulsar Polarimetry

A Search for Neutron Star Precession and Interstellar Magnetic Field Variations Via Multiepoch Pulsar Polarimetry

In order to study precession and interstellar magnetic field variations, we measured the polarized position angle of 81 pulsars at several-month intervals for four years. We show that the uncertainties in a single-epoch measurement of position angle are usually dominated by random pulse-to-pulse jit...

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Bibliographic Details
Published in:The Astrophysical journal Vol. 721; no. 2; pp. 1044 - 1055
Main Authors: Weisberg, J. M, Everett, J. E, Cordes, J. M, Morgan, J. J, Brisbin, D. G
Format: Journal Article
Language:English
Published: Bristol IOP Publishing 01-10-2010
IOP
Subjects:
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COSMIC RADIO SOURCES
Earth, ocean, space
Exact sciences and technology
INTERSTELLAR MAGNETIC FIELDS
MAGNETIC FIELDS
NEUTRON STARS
POLARIMETRY
POLARIZATION
PULSARS
PULSES
RANDOMNESS
STARS
Polarization
Neutron stars
Uncertainty
pulsars: general
Interstellar magnetic fields
Angle of deviation
Precession
Pulsars
Standard deviation
Position angle
Polarimetry
Magnetic fields
ISM: magnetic fields
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Summary:In order to study precession and interstellar magnetic field variations, we measured the polarized position angle of 81 pulsars at several-month intervals for four years. We show that the uncertainties in a single-epoch measurement of position angle are usually dominated by random pulse-to-pulse jitter of the polarized subpulses. Even with these uncertainties, we find that the position angle variations in 19 pulsars are significantly better fitted (at the 3{sigma} level) by a sinusoid than by a constant. Such variations could be caused by precession, which would then indicate periods of {approx}(200-1300) days and amplitudes of {approx}(1-12) degrees. We narrow this collection to four pulsars that show the most convincing evidence of sinusoidal variation in position angle. Also, in a handful of pulsars, single discrepant position angle measurements are observed which may result from the line of sight passing across a discrete ionized, magnetized structure. We calculate the standard deviation of position angle measurements from the mean for each pulsar and relate these to limits on precession and interstellar magnetic field variations.
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/721/2/1044