Since their discovery in 1968, the known population of radio pulsars has grown to ~2000, and comprises several different groups which display markedly different behaviour from one another. Despite the large number of known sources, there are several scientific justifications for new wide-area searches for pulsars. These are outlined in this work, but include population studies, the evolutionary history of pulsars, and the possible detection of gravitational waves through high-precision timing.Previous pulsar surveys have been limited by (a) the hardware used to record the survey data; and, (b) the computational power that has been available to process this data. This has resulted in an observational bias which made the discovery of distant, highly dispersed pulsars, very difficult. Particularly affected by this are the most rapidly-rotating pulsars --- the millisecond pulsars --- which are known to rotate with spin periods as short as 1.4 ms. Since these are also some of the most interesting sources, with the greatest potential for high-precision timing, it is important to perform searches both deep into the Galactic plane and covering the whole sky, with sufficient time resolution to discover more millisecond pulsars. This thesis describes two such pulsar surveys, in which several discoveries have been made.The first is a survey of the Galactic plane at an observing frequency of 6.5 GHz, motivated by the need to discover pulsars at the Galactic centre. This survey resulted in the discovery of three pulsars, all of which are at distances > 9.5 kpc.The second is the ongoing High Time Resolution Universe pulsar survey using the 64-metre telescope at Parkes. This survey will make observations of the whole of the Southern sky using extremely high time resolution and narrow frequency channels. Preliminary results from the survey are presented here, including the discovery of 5 millisecond pulsars at relatively large distances, including one for which regular eclipses are observed. Also discussed are some interesting individual discoveries from the survey; a radio magnetar, a millisecond pulsar with potential for high-precision timing, and a millisecond pulsar with a companion of extremely low mass.
|Date of Award
|1 Aug 2011
- The University of Manchester
|Benjamin Stappers (Supervisor)