Differential frequency-dependent delay from the pulsar magnetosphere
Journal article, 2013
Some radio pulsars show clear "drifting subpulses", in which subpulses are seen to drift in pulse longitude in a systematic pattern. Here we examine how the drifting subpulses of PSR B0809+74 evolve with time and observing frequency. We show that the subpulse period (P-3) is constant on timescales of days, months and years, and between 14-5100 MHz. Despite this, the shapes of the driftbands change radically with frequency. Previous studies have concluded that, while the subpulses appear to move through the pulse window approximately linearly at low frequencies (<500 MHz), a discrete step of similar to 180 degrees in subpulse phase is observed at higher frequencies (>820 MHz) near to the peak of the average pulse profile. We use LOFAR, GMRT, GBT, WSRT and Effelsberg 100-m data to explore the frequency-dependence of this phase step. We show that the size of the subpulse phase step increases gradually, and is observable even at low frequencies. We attribute the subpulse phase step to the presence of two separate driftbands, whose relative arrival times vary with frequency - one driftband arriving 30 pulses earlier at 20 MHz than it does at 1380 MHz, whilst the other arrives simultaneously at all frequencies. The drifting pattern which is observed here cannot be explained by either the rotating carousel model or the surface oscillation model, and could provide new insight into the physical processes happening within the pulsar magnetosphere.
drifting subpulses
pulsars: individual: PSR B0809+74
model
radiation
telescopes
polarization
emission
telescope
stability
profiles
pulsars: general
radio pulsars
psr b0809+74
Author
T. E. Hassall
University of Southampton
B. W. Stappers
University of Manchester
P. Weltevrede
University of Manchester
J. W. T. Hessels
Netherlands Institute for Radio Astronomy (ASTRON)
Anton Pannekoek Institute for Astronomy
A. Alexov
Anton Pannekoek Institute for Astronomy
Space Telescope Science Institute (STScI)
T. Coenen
Anton Pannekoek Institute for Astronomy
A. Karastergiou
University of Oxford
M. Kramer
University of Manchester
Max Planck Society
E. F. Keane
Max Planck Society
V. I. Kondratiev
Netherlands Institute for Radio Astronomy (ASTRON)
J. van Leeuwen
Netherlands Institute for Radio Astronomy (ASTRON)
Anton Pannekoek Institute for Astronomy
A. Noutsos
Max Planck Society
M. Pilia
Netherlands Institute for Radio Astronomy (ASTRON)
M. Serylak
Institut National des Sciences de l'Univers
Centre national de la recherche scientifique (CNRS)
C. Sobey
Max Planck Society
K. Zagkouris
University of Oxford
R. Fender
University of Southampton
M. E. Bell
University of Southampton
The University of Sydney
J. Broderick
University of Southampton
J. Eisloffel
H. Falcke
Radboud University
Netherlands Institute for Radio Astronomy (ASTRON)
J. M. Griessmeier
Institut National des Sciences de l'Univers
Centre national de la recherche scientifique (CNRS)
M. Kuniyoshi
Max Planck Society
J. C. A. Miller-Jones
Curtin University
Anton Pannekoek Institute for Astronomy
M. W. Wise
Anton Pannekoek Institute for Astronomy
Netherlands Institute for Radio Astronomy (ASTRON)
O. Wucknitz
University of Bonn
Max Planck Society
P. Zarka
Observatoire de Paris-Meudon
A. Asgekar
Netherlands Institute for Radio Astronomy (ASTRON)
Fabien Batejat
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
M. J. Bentum
Netherlands Institute for Radio Astronomy (ASTRON)
G. Bernardi
University of Groningen
P. Best
University of Edinburgh
A. Bonafede
University of Hamburg
Jacobs University Bremen
F. Breitling
Leibniz Institute for Astrophysics Potsdam
M. Brüggen
University of Hamburg
H. R. Butcher
Australian National University
Netherlands Institute for Radio Astronomy (ASTRON)
B. Ciardi
Max Planck Society
F. De Gasperin
University of Hamburg
Max Planck Society
J. P. de Reijer
Netherlands Institute for Radio Astronomy (ASTRON)
S. Duscha
Netherlands Institute for Radio Astronomy (ASTRON)
R. A. Fallows
Netherlands Institute for Radio Astronomy (ASTRON)
C. Ferrari
Université Nice Sophia Antipolis (UNS)
W. Frieswijk
Netherlands Institute for Radio Astronomy (ASTRON)
M. A. Garrett
Netherlands Institute for Radio Astronomy (ASTRON)
Leiden University
A. W. Gunst
Netherlands Institute for Radio Astronomy (ASTRON)
G. Heald
Netherlands Institute for Radio Astronomy (ASTRON)
M. Hoeft
E. Juette
Ruhr-Universität Bochum
P. Maat
Netherlands Institute for Radio Astronomy (ASTRON)
J. P. McKean
Netherlands Institute for Radio Astronomy (ASTRON)
M. J. Norden
Netherlands Institute for Radio Astronomy (ASTRON)
M. Pandey-Pommier
Leiden University
Lyon Observatory
R. Pizzo
Netherlands Institute for Radio Astronomy (ASTRON)
A. G. Polatidis
Netherlands Institute for Radio Astronomy (ASTRON)
W. Reich
Max Planck Society
H. Rottgering
Leiden University
J. Sluman
Netherlands Institute for Radio Astronomy (ASTRON)
Y. Tang
Netherlands Institute for Radio Astronomy (ASTRON)
C. Tasse
Observatoire de Paris-Meudon
R. Vermeulen
Netherlands Institute for Radio Astronomy (ASTRON)
R. J. van Weeren
Harvard-Smithsonian Center for Astrophysics
Netherlands Institute for Radio Astronomy (ASTRON)
Leiden University
S. J. Wijnholds
Netherlands Institute for Radio Astronomy (ASTRON)
S. Yatawatta
Netherlands Institute for Radio Astronomy (ASTRON)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 552 A61Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201220764