Note that these are suggested project topics rather than projects for which a funded PhD place is necessarily available and will evolve over time. Please contact the supervisor concerned for details.
Other joint astrophysics projects are also available with the Institute for Gravitational Research, mostly on the analysis of recent gravitational wave data: contact Dr G. Woan for details.
Supervisors Dr G. Woan, Dr M. Hendry
The Square Kilometre Array (www.skatelescope.org) is an exciting, highly ambitious project to build the world's largest radio telescope. Glasgow is part of the UK SKA Design Study consortium, a 4-year international project which brings together European and international astronomers to formulate and agree the most effective SKA design. The aim of this project will be to investigate some of the ground-breaking science questions which the SKA will address when it becomes fully operational around 2015. These questions range from the fundamental physics of pulsars and black holes to understanding the nature of dark energy and the process of galaxy formation. Examples of possible project topics include:
Supervisor: Dr A. MacKinnon
Free neutrons in space testify to the bombardment of some baryonic target (Sun, planets) by energetic ions. They are a crucial diagnostic of transient solar ion acceleration (in flares, but possibly also at other times). They will also result from other cosmic targets bombarded by cosmic rays. The main focus of this project will be the development of data analysis techniques for innovative neutron detectors, being developed by our collaborators in the University of New Hampshire (UNH) with a view to flying on future inner heliosphere space missions. A major side theme will be the modelling of nuclear processes that produce free neutrons, to explore fully their diagnostic potential. The project will involve working closely with collaborators in UNH and in Bern, Switzerland.
Supervisors: Dr M. Hendry; Dr L. Teodoro
The key challenge for modern cosmology is understanding the process of galaxy formation: the evolutionary transition from an almost perfectly smooth CMBR to the complex patterns of galaxy clustering that we observe today. The so-called 'gravitational instability paradigm' - which models the formation of structure on large scales as solely due to the action of gravity - has proved to be a remarkably successful description of galaxy clustering.
Our research at Glasgow involves several different, although closely related, topics within this exciting and challenging field, and there are excellent PhD project opportunities in each of these topics:
1) investigating new statistical tools for describing the distribution of dark matter halos in 'state of the art' computer simulations of large scale structure formation.
2) designing new 'mock' galaxy catalogues, mimicking current (e.g. 6dF) and proposed future (e.g. SKA) galaxy surveys, using semi-analytical methods to 'populate' dark matter halos with galaxies.
3) developing a new, wave-mechanical, approach to simulations of large scale structure, exploiting important parallels between the classical equations of cosmic structure formation and the Schrodinger equation of quantum mechanics. This exciting new approach has the potential to overcome the numerical 'discreteness' effects to which conventional particle simulations are prone, and hence may place powerful constraints on the 'cuspiness' of dark matter halo profiles on small scales.
Supervisor: Dr. L. Fletcher
Solar flares are abrupt and transient brightenings in the solar atmosphere, resulting from the release of a colossal amount of energy which was previously stored in the solar magnetic field. Many questions in flare physics centre around the storage and release of this energy, and address topics such as magnetic field structures in the corona, energy conversion and particle acceleration, and production of radiation. Observations with the recent generation of solar satellites - in particular the Transition Region and Coronal Explorer satellite, TRACE, reveal sites of extremely bright ultraviolet emission in the lower solar atmosphere occurring during solar flares, the position and intensity of which change as the flare proceeds. The production of this emission is not yet understood, although it is almost certainly associated with fast particles accelerated during the flare, and the changes observed may in principle be used to track the evolution of the coronal magnetic field, which is not readily accessible by other observational means.
The main aims of the project will be
The project will thus include computational work, observational analysis and theoretical modelling of magnetic fields. It is well-suited to candidates with and interest in the Sun, and a background in Physics and Astronomy, or Physics/Astronomy and Maths.
Supervisor: Dr D. Diver, Dr H. Potts
Pulsar atmospheres consist of electron-positron plasmas. Such plasmas are very energetic, and given that the positive and negative species have equal mass, these plasmas have unique properties. We are investigating wave propagation in magnetised pair plasmas, from the perspective of trying to understand the wave processes that could contribute to the pulsar radiation source. To date we have examined the radiation damping of quasi-linear electron-positron plasma oscillations, using computer simulations. Complex analysis has allowed us also to reformulate the Bernstein modes in a weakly relativistic pair plasma, with a view to studying how such weakly damped magnetic modes might act as a vehicle for radiation transport in a non-uniform plasma. The landau damping of fully relativistic pair plasmas is also a developing investigation.
The project will be concerned with
Supervisor: Dr D. Diver, Dr H. Potts
A project to model (i) the impact that a plasma source can have on neutral gas and (2) the time evolution of the sheath around a free-surface in a streaming plasma.
These projects are computational and analytical in character, sharing basic plasma physics but applied to different situations. Several competing scale-lengths will contribute to the complexity of the evolution: the collisional mean free path of the plasma, the free-fall sheath length scale, the typical wavelength of deformation of the conductor and the scale-length for non-uniformity of the plasma flow. The competition between these characteristic scales will lead to strong time-dependence in the local electric field, and the consequence non-linear feedback on both the impinging plasma flow, sonic disturbances and the free-surface deformation of the obstruction. The most obvious application of the sheath stabilitiy analysis is to space tethers in the solar wind environment, but the relevance extends beyond this to spacecraft generally, and to laboratory plasmas used for surface processing in which the surface topography evolves self-consistently. Analysis of photoionisation of the lunar regolith, and the consequent development of the lunar plasma exosphere, is another possible research project. For the plasma acoustics, the direct generation of sound waves by plasma heating has a long history, but recent advances in plasma technology mean that this exciting problem can be tackled afresh. Our particular interest is in the generation of pressure disturbances orders of magnitude greater than normal acoustics, but in specialised vessels that suppress shock formation.
Supervisor: Dr D. Diver, Dr H. Potts
The evolution and character of plasma dust has wide-ranging implications for astrophysics and laboratory plasmas, including fusion and plasma processing. Whilst there are many studies of plasma crystals, in which pre-formed grains are injected into a plasma, there are fewer investigations of the more profound problem of growing the dust from first principles directly in the plasma. Condensation mechanisms, in which fluid agglomerates around a seed particle in the classical Salpeter approach, are not as relevant in the plasma context, since in the latter the local electrostatic conditions can influence enormously the conditions for dust growth, leading in some cases to naturally occurring prolate-spheroidal dust shapes. The implications of non-spherical dust grains for electromagnetic extinction and polarisation in astronomical observations are well-known, but though progress has been made in characterising the effects of composite grain structure and spheroidal shapes, there is little in the way of a holistic approach to the problem. We aim to model the formation and evolution of dust in the original supporting plasma, and then simulate the remote diagnosis of the medium by computational analysis of the resulting polarisation signatures. We will examine the electrostatic charging of dust over a range of scales, and its subsequent growth, with and without a magnetic field. Surface chemistry, particularly the absorption of gases, will be accommodated where appropriate.
Supervisor: Dr D. Diver, Dr L. Teodoro & Dr M. Hendry
The role of the magnetic field in medium scale cosmic evolution is not well understood, given the complexity of the possible interactions. We aim to focus on two specific areas: (1) the natural evolution of jets and other linear structures; (2) the development of density structure in large-scale mixed flows of plasma and neutrals; and (3)the evolution of magnetic fields in extreme circumstances, from the weak but large-scale cosmological magnetic field, to the intense, but highly-localised pulsar field.
(1) Self-guiding magnetic fields arising from energetic plasmas have been modelled (computationally and analytically) in the context of dense, relativistic plasma flows in laser-plasma interactions. These fields are produced by Inverse Faraday Rotation, in which the internal plasma currents create an axial magnetic field component that is projected ahead of the plasma front, so guiding the direction of the flow. Such phenomena could play a role in the evolution of large-scale astrophysical jets, in which rectilinear structures stretch for remarkably large distances with very little deviation, but with tell-tale internal structure that is suggestive of strong axial plasma rotation.
(2) Plasma-neutral gas mixtures are a unique medium, if momentum transport is incorporated between the charged fluid and its neutral counterpart. Density structures evolve that are hybrids of the plasma response to magnetic perturbations, and the neutral gas sonic pressure waves. The resulting mixture leads to an anisotropic medium that can support a large variety of pressure variations, with disturbances propagating with complex group and phase velocities. Linear computational studies already hint at beautiful structures; we plan to push on with a fully non-linear model that will allow larger perturbations to evolve.
(3) Magnetic field evolution in the early universe prior to recombination is uncertain; however, the effect of recombination must be significant, since the large-scale formation of neutrals has a major impact on the conduction current. Removing the charged particle current carriers must induce an electromagnetic response, and this project will address the relevant physics: by incorporating the correct electromagnetism and plasma kinetics, we will investigate (a) the acceleration of ambient charged particles by the creation of a displacement current, and (b) the intrinsic evolution of the distribution function during recombination, and the interpretation of the temperature during this behaviour.
Supervisor: Dr D. Diver, Dr H. Potts
A numerical and theoretical investigation of Alfven ionization processes in strong solar photospheric flows. The kinetic energy of mixed-species neutral gas flowing through a magnetised plasma can result in pockets of energetic plasma electrons (confined by the magnetic field) that are able to ionize specific neutrals in the flow via electron-impact ionization. Such a process has already been implicated in creating the anomalous chemical composition of the solar wind; we aim to extend this study by correlating solar surface flows and magnetic structures together with improved data on solar abundances to clarify the overall picture of ionised species evolution in the magnetic environment of the sun. Specifically, this project will address the creation and transport of particular ions via interaction with a defined magnetic structure, investigating the differential diffusion of minority species in order to model directly the resulting abundance anomalies in the solar wind. This will allow us to incorporate time-dependence arising from the photospheric flows and the character of the magnetic structures, as well as longer timescales invoked by the solar cycle.
The Group has extensive expertise in diagnostics and modelling of structure and dynamics of the atmospheres of both Early Type (hot) and Late Type (cool) stars. This includes photometry. spectrometry, polarimetry, and microlensing. This should replace the existing entry
Hot massive stars lose mass in their winds at a prodigious rate - some as high as a solar mass in 10,000 years. This has major consequences for massive star evolution and for the structure and chemical composition of interstellar matter. Though it is accepted that these winds are mainly driven by radiation pressure, their remain many unanswered questions about them : what other forces - e.g. magnetic, rotational, pulsational - generate the diverse structures seen in the massive winds of different stellar classes - clumps, disks, jets - and how does radiation manage to impart such high momentum as well as energy to the winds? Opportunities exist to tackle aspects of one or more of these issues via a mix of multimode (spectroscopic, polarimetric, photometric) analytic and numerical modelling and 'data-mining' of the rich and growing multi wavelength information archive of observations. These come from a range of observatories and space missions - IUE, HST, Chandra, XMM Newton, FUSE - and gravitational microlensing. Work in this area involves collaborations with E.Tennessee and Wisconsin.
The most energetic phenomena on cold stars are stellar flares and CMEs - analogues of magnetic energy release on the sun but often with vastly scaled up total energy. As intrumentation advances, stellar flare observations increasingly advance toward the current quality (sensitivity, resolution etc) of solar flare data, Work in this area will pursue solar/stellar analogies and use data from the latest instruments at all wavelengths.
Supervisors : Prof. J. C. Brown; Dr A.L. MacKinnon; Dr. L. Fletcher
Particle acceleration is a ubiquitous cosmic phenomenon from the scale of
active galactic nuclei down to planetary magnetospheres with the resulting fast
particles having an energy density high enough to influence their environment.
Acceleration processes are far from well understood, either theoretically or
phenomenologically from data interpretation. The nearby sun offers a unique
opportunity to study particle acceleration via high resolution spectra and images
at radio to gamma-ray wavelengths from ground and space observatories, and by
direct particle detection in space, (Solar energetic particles are a key component
of Space Weather and its effects on the Earth environment.) As the UK Co-I Group
on the NASA high energy RHESSI solar mission (http://hesperia.gsfc.nasa.gov/hessi/)
, and with close involvement in other solar missions, Glasgow is involved in
a wide range of theoretical and numerical projects on diagnosing data on solar
electron and ion acceleration. Results are used as tests of particle acceleration
and transport models and of the role of particles in heating of the flaring
and active solar atmosphere. A range of possible thesis topics is available
in these areas, all involving varying mixes of : data mining and reduction;
signal analysis (spectrum and image deconvolution); tests of phenomenological
models against data; numerical simulations and analytic modelling of plasma/particle
processes. Work in this area involves numerous collaborations including NASA
Maryland, Berkeley, Alabama, Lockheed-Martin CA, Graz, Genova, Paris and Zurich.
Supervisors: Dr. N. Labrosse; Dr. L. Fletcher
Solar prominences are large magnetic structures confining a cool plasma in the hot corona, surrounding a polarity inversion line in the photospheric magnetic field. Typically, the prominence plasma is one hundred times cooler and denser than its coronal surroundings, raising important questions about origin and energy equilibrium. Once prominences are formed, they can remain stable for over a solar rotationand are an integral part of the solar corona. The conditions for their stability are inherently related to the associated magnetic configuration. Some disappear quietly, but most disappear in a more dramatic fashion in association with a Coronal Mass Ejection (CME). A CME has severe impacts on the heliosphere and planetary environments, and thus has become a central topic of research in the field of Space Weather. Prominences are one of the most easily traceable CME components. Hence they can yield important information concerning the CME magnetic structure from initiation through eruption. The aim of the project is to develop a model of the plasma during the activation and the eruption of the prominence. It will be based primarily on non-local thermodynamic equilibrium modelling of the radiative transfer and the synthesis of spectral lines formed under different physical conditions. This will be compared with extreme ultraviolet observations from SOHO, TRACE, Hinode, and STEREO spacecrafts. The combination of modelling and observations will place good constraints on plasma parameters such as density, temperature, velocities, and the fine structuring of the prominence. The work may involve several international collaborations, including France, Czech Republic, USA.Supervisors: Dr E. P. Kontar; Prof. J. C. Brown; Dr. L. Fletcher
Physics of wave-particle, wave-wave interaction in the heliosphere. Wave acceleration of particles in solar flares. Coherent plasma emission from energetic particles, plasma and shock waves. Interaction or electromagnetic emission with plasmas. Development of solar radio emission models for the next generation radio data from LOFAR (Glasgow is a member of the LOFAR UK Consortium) and FASR. Diagnostics of particles and waves via their electromagnetic emission.Supervisors: Dr. L. Fletcher, Dr. J. I. Khan
The Hinode ("Sunrise" in Japanese) solar satellite was launched in September 2006, and has been returning high quality data ever since. This includes coronal images in the soft X-ray range, chromospheric images in the optical to ultraviolet, photospheric vector magnetograms, and extreme ultraviolet spectroscopy of coronal and transition-region plasmas. In the rise towards the next solar maximum in around 2011 the level of solar activity will increase, and Hinode will become a prime mission for studying solar flares. Solar flares are abrupt and transient brightenings in the solar atmosphere, resulting from the release of a colossal amount of energy. They are related to ejections of mass, generation of large-scale waves, and particle acceleration. Since the quality of the flare data are as yet relatively unknown, this project could go in a number of directions depending on the interests of the student, but priorities are:Data analysis is core to this project, however candidates with a strong interest in theory will be encouraged to explore theoretical modeling relevant to their observations.