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A&A 483, 13-14 (2008)
DOI: 10.1051/0004-6361:20079211
Correlation of the scattering and dispersion events in the Crab Nebula pulsar
A. Kuzmin1, B. Ya. Losovsky1, C. A. Jordan2, and F. G. Smith21 Pushchino Radio Astronomy Observatory of Lebedev Physical Institute, Russia
2 University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire, SK11 9DL, UK
e-mail: fgs@jb.man.ac.uk
(Received 7 December 2007 / Accepted 23 February 2008)
Abstract
In separate series of observations of the Crab pulsar, pulse
broadening due to scattering was measured at 111 MHz, and variations
of dispersion due to pulse delay were measured at higher radio
frequencies. In a remarkable event lasting 200 days a large
increase occurred in both parameters and with similar time signatures.
The increases in scattering and dispersion measure observed over the
200 days MJD 53 950-54 150 are attributable to the effects of an ionised
cloud or filament crossing the line of sight. The cloud would be
1011-1012 m across, with electron density
103-104 cm-3. The increased scattering might originate within the cloud itself, or the moving filament might induce turbulence in a separate higher density cloud in
the line of sight.
Key words: pulsars: general -- pulsars: individual: Crab -- ISM: supernova remnants
© ESO 2008