Observation of nulling in radio pulsars with the Ooty Radio Telescope
Abstract
The recently upgraded Ooty Radio Telescope was used to observe pulse nulling in 10 pulsars. The fraction of time alpha that a pulsar spends in the nulled state is <=2.5 per cent for PSR 0149-16, <=7.0 per cent for PSR 0942-13 and 44.6+/-1.3 per cent for PSR 0031-07. The remaining seven alpha-values are consistent with previous estimates. This paper suggests an improved scheme of obtaining alpha for `weak' pulsars. In most pulsars, the width of the individual pulse is much smaller than that of the integrated pulse. The energy in a pulse can be best estimated by integrating the power over the width of the individual pulse, and not over that of the integrated pulse. An equivalent scheme involves summing up, from each individual pulse, a pre-determined number of extreme-valued powers. This significantly improves the accuracy of the nulling data. This method is used to obtain the statistics of the burst and null durations in PSR 0031-07. Both phenomena consist of at least two distinct random processes: (a) a short-time-scale process that can be represented by an exponential distribution with a width of ~=2.5 periods, and (b) a long-time-scale process that can be represented, for the burst phenomenon, by a Rayleigh distribution with a width of ~=24 periods. The duration of a burst is weakly correlated with that of the preceding null. The onset of a burst or a null is usually abrupt, but sometimes occurs over several periods. There is no significant difference between the average first and last pulses of a burst.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 1995
- DOI:
- 10.1093/mnras/274.3.785
- Bibcode:
- 1995MNRAS.274..785V
- Keywords:
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- METHODS: DATA ANALYSIS;
- PULSARS: GENERAL;
- PULSARS: INDIVIDUAL: PSR 0031-07