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PhD Projects 2005

Pulsars provide the nearest thing to a physicist's dream come true. Being the end-point of stellar evolution, they are densest bodies next to black holes and give us an insight into the most extreme physical conditions of matter density, pressure and magnetic field observable by man. They also provide the most precise clocks known to humankind for undertaking unique experiments of gravitation and general relativity. Furthermore, they can be used as probes of the distribution of ionised material and magnetic field in the Galaxy with a precision which nothing else can. We use the telescopes at Jodrell Bank, Parkes (Australia) and Arecibo (Puerto Rico) in this work and frequently travel to the foreign instruments to make observations. The pulsar group at Jodrell Bank are arguably the most productive in the world in this area and have discovered more than three-quarters of the known population of these elusive and fascinating objects.

There are several main active areas of research in the general area of pulsar astronomy which would support projects which would be ideal for students, starting in September 2005. We outline each of these areas below.

The Galactic Pulsar Population

The Parkes Multibeam pulsar survey led by Jodrell Bank's pulsar group in collaboration with the ATNF in Australia has been the most successful survey in pulsar history. Just completed, it is a sensitive survey of a 10 deg-wide strip of the Galactic plane from Galactic longitude l=260 deg to l=50 deg. Using a 13-beam receiver on the 64-m Parkes radio telescope in Australia, it has already discovered about 700 new pulsars. We expect that after processing of all data that this one survey will finally have found as many pulsars as all previous pulsar surveys put together (see red points in figure below). Obviously, the newly discovered pulsars form an extremely valuable sample for studies of Galactic population of pulsars.

The observed population is biased by certain selection effects and does not necessarily represent the true population of pulsars in the Galaxy. However, by modelling the well-known selection effects, the salient properties of the underlying population (distribution in space, spin period, magnetic fields, luminosities etc) can be determined, allowing important conclusions relevant for the population and evolution of massive stars. This project would be ideal for a student with a good background in programming, and an interest in statistical methods in astronomy.

Please contact Dunc Lorimer ( or Michael Kramer ( for further details.

Probing the Interstellar Medium using Pulsars

The interstellar medium is not uniform but shows a small degree of clumpiness in its contents of free electron. These density fluctuations responsible for scintillation and scattering of radio signals propagating through the interstellar medium (ISM). Scattering of pulsar signals causes the signal to arrive from different, multiple ray paths with different geometric lengths leading to a temporal broadening of the pulse shape commonly known as the scatter broadening time. Further, along different ray paths the radiation acquires random phases which cause interference in the plane of the observer to produce diffraction patterns which are easily observable as intensity variations.

These effects are a strong function of frequency, which allows to determine the physical quantities involved in direction of a given pulsar. Using multi-frequency observations made with the Parkes radio telescope and the Giant Metrewave Radio Telescope (GMRT) in India (shown on the right), the student working on this project would determine the scattering parameters and produce a model of (enhanced) scattering regions in the Galaxy to explore the still not-well known turbulence spectrum of the interstellar medium. Understanding the turbulence towards different directions of the Milky Way is very important when studying and modelling the observed population of radio pulsars. Only with a correct model of the ISM can we attempt to understand how pulsars are born and distributed in the Galaxy and can make predictions for future surveys of the sky.

With the already available data significant contributions to this project can be within a MSc project. The scope of the addressed scientific question would allow to extend this project to a PhD thesis.

Please contact Michael Kramer ( or Maura McLaughlin ( for further details.

Last updated Thu Oct 28 18:46:48 BST 2004