Scintillation parameters for 49 pulsars
S. Johnston (RCfTA, University of Sydney, Australia),
L. Nicastro (ITeSRE-CNR, Via Gobetti 101, 40129 Bologna, Italy),
B. Koribalski (ATNF, CSIRO, Australia)
Abstract
We report on multi-epoch, multi-frequency observations of 64 pulsars with
high spectral and time resolution.
Scintillation parameters were obtained for 49 pulsars,
including 13 millisecond pulsars. Scintillation speeds were derived for
all 49, which doubles the number of pulsars with speeds measured in this way.
There is excellent agreement between the scintillation speed
and proper motion for the millisecond pulsars in our sample using the
simple assumption of a mid-placed scattering screen. This indicates that
the scale-height of scattering electrons is similar to that of the
dispersing electrons.
In addition, we present observations of the Vela pulsar at
14 and 23 GHz and show that the scintillation bandwidth scales as
freq^3.93 over a factor of 100 in observing frequency.
We show that for PSR J0742-2822, and perhaps PSR J0837-4135, the Gum
Nebula is responsible for the high level of turbulence along their
lines-of-sight, contrary to previous indications.
There is a significant correlation between the scintillation speeds
and the product of the pulsar's period and period derivative for
the `normal' pulsars. However, we believe this to be caused by selection
effects both in pulsar detection experiments and in the choice of pulsars
used in scintillation studies.