The Astrophysics Research Programme at Newcastle University

Lead Research Organisation: Newcastle University
Department Name: Mathematics and Statistics

Abstract

The proposed astrophysics research programme at Newcastle University includes six independent projects. Although all of these projects are primarily theoretical in nature, most are directly motivated by recent observations. Four of the projects are linked, in the sense that they all deal with the motions of electrically-conducting fluids (magnetohydrodynamics), albeit over a vast range of scales. In the planetary context, we shall investigate the ways in which the internal fluid motions generate and sustain large-scale magnetic fields, via a dynamo mechanism, by considering a model of convection in a rotating spherical shell. We shall also investigate the phenomenon of large-scale polarity reversals, in which the radial component of the large-scale planetary magnetic field changes sign. In the case of the Sun, recent high resolution observations of the solar surface have revealed a complex distribution of small-scale magnetic fields. Given that the origin of these magnetic features is still under debate, we shall investigate the possibility that these fields are generated by a local dynamo resulting from the near-surface convective motions. The evolution of certain stellar systems is strongly influenced by the presence of an accretion disc, which is a thin structure containing material that is in orbital motion around the star. We shall use a range of analytic (and semi-analytic) techniques to investigate the complex coupling between an accretion disc and the central star's magnetic field. On much larger scales, we will consider magnetic fields in the interstellar medium. Our aim here is to use numerical simulations to address the fundamental question of how cosmic rays (charged particles) propagate through realistic, dynamo-generated, interstellar magnetic fields, ultimately aiming to generate results that can be used to interpret observations. There are two further projects in this proposal. In the first of these we propose to investigate the dynamics of neutron stars, by considering a model of interacting vortices in a superfluid (a fluid with no friction). This is an emerging area of research, with possible links to recent laboratory experiments. In our cosmology project, we shall consider the observational signatures of certain early universe cosmological models. This will tie in with the imminent public release of data from the Planck satellite (which is expected in January 2013), so this is an excellent time to be carrying out this research.

Planned Impact

As indicated above, our results will be of interest to scientists working in wide range of different fields. We intend to disseminate our results by attending conferences and by publishing our findings in high impact-factor refereed journals. Although our work is primarily theoretical, it is motivated by observations, and our intention is to produce results that can be used to interpret observational data. It will therefore be important for us to communicate effectively with observers. We intend to achieve this by using existing collaborative links, and by presenting results at carefully selected conferences. Furthermore, we shall invite observers to visit Newcastle, using the visitor money that we are requesting as part of this grant.

On an individual level, this research will have a positive impact upon the careers of the PDRAs and PhD students. Clearly, they will gain important experience and training in their specific subject areas. All of the projects which involve PhD students and PDRAs will involve some numerical work. This will be useful training for the individuals concerned. They will also develop their communication skills by presenting research at conferences. Even if the PDRAs and PhD students do not go on to pursue an academic career, such skills are highly valued in many other employment sectors.

It is also important to communicate with the general public. We plan to carry out the following outreach activities:

1) One of the CoI's already does outreach work with local schools, including giving "Masterclasses" on Applied Mathematics and lecturing at our "Partners" summer schools for pupils attending local schools, many in deprived areas, which do not send many students to University. Building upon our previous experience in this area, we intend to introduce simple ideas from our research into these outreach activities.

2) Using existing links with the Centre for Life (a large science exhibition in Newcastle city centre) and the Newcastle Literary and Philosophical Society, we shall present our work in a series of public lectures. Recent events of this sort have been very successful, and we plan to build on these.

More details of our Knowledge Exchange and Outreach activities can be found in the Pathways to Impact Document.

Publications

10 25 50
 
Description Neutron stars are small, dense astrophysical bodies that are often rotating very rapidly. This aim of this project is to explain glitches (sudden increases in the spin rate) that are observed in some of these objects. It is believed that this phenomenon is associated with complex vortex dynamics in the superfluid stellar interior. We have developed an idealised model to study this process. The PhD student who has been carrying out the work has developed a numerical code, testing this by reproducing known results relating to the formation of glitches in two spatial dimensions. Generalising the model to three spatial dimensions, these glitches seem to disappear (a negative result that appears to be robust to changes in the model parameters). To shed further light onto the nature of glitches in three dimensions, we are (with the aid of another internally funded PhD student) currently focusing upon a two-fluid approach, with the neutron superfluid coupled to another fluid consisting of the protons' flux tubes. We hope that this new approach will soon yield some interesting results, providing further new insights into the physics underlying glitches.
Exploitation Route We plan to publish our findings in highly-regarded international journals and we will also attend conferences to disseminate our results as widely as possible. The superfluids aspect of this project means that our results will be of interest to scientists working in quite a broad range of fields, ranging from theorists through to experimentalists. We will choose conferences carefully so as to ensure that all possible avenues for academic impact are explored.
Sectors Other