PhD Projects 2022

Below are research project opportunities within the Astronomy & Astrophysics group. Most are suggested project topics without funding necessarily available and will evolve over time. There is a range of competitive scholarship funding and more information is available on the college website.

Formal applications are made through The College of Science and Engineering and students need to indicate the project title or area they would like to work in. So the prospective students should first contact the supervisor concerned for more details of the projects.

The current deadline for applications is Friday February 11th 2022 – please contact us for more information and details of potential funding.

Chromospheric observations of Solar Flares – Studies with IRIS

Supervisor: Prof Lyndsay Fletcher and Dr Nicolas Labrosse

Solar flares are identified by strong radiation increases across the electromagnetic spectrum, but especially in radiation from the solar chromosphere. This research project will focus on understanding the properties of the solar flare chromosphere during the rapid burst of emission that occurs at the flare onset (the impulsive phase) and also during the slower evolutionary phase that follows as the solar atmosphere adjusts towards a new equilibrium. The project will involve the use of data from the Interface Region Imaging Spectrometer (IRIS), supported by the Solar Dynamics Observatory, to diagnose the properties of the intense, hot sources of flare emission. Topics for the proposed study include:

An image of a solar flare

Carrying out spectroscopic analyses of the emission from flare footpoints and ribbons to look at the dynamics of these regions at different stages of the flare;

Understanding the horizontal and vertical structuring of the flare footpoint and ribbon emission;

Determining the relationship between the fine-scale spatial structures in the flare emission and the pre-flare atmosphere, and between the flare emission and the underlying magnetic field

The project will utilise high resolution data from a number of spacecraft, and involves programming in Python or IDL. Depending on the interest of the student, numerical modeling in collaboration with colleagues from Oslo is also a possibility.

Optical studies of solar flares

Supervisor: Prof Lyndsay Fletcher

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A solar flare in H alpha observed at high resolution with the IBIS instrument at the Dunn Solar Telescope

Solar flares are dramatic bursts of particles and radiation from the solar atmosphere produced when energy is released suddenly from the coronal magnetic field. Although flares have a very beautiful appearance at short wavelengths (extreme UV and X-rays), the majority of the flare radiation is emitted in the optical part of the spectrum, which is thus a region rich in diagnostic information. This project will focus on the analysis of ground-based solar flare observations, taken with the Swedish Solar Telescope and other ground-based instruments. Possible research topics include

  • Optical line plasma diagnostics – e.g. using high-order Balmer lines to determine the electron density and its evolution through a flare;
  • Spatial and temporal characterisation of H-alpha and Ca 8542 emission, including spectropolarimetry and comparison with model predictions;
  • Examination of the magnetic field variations at the location of flare optical emission.

The project will utilise high resolution data from ground-based instruments (but may also involve Solar Optical Telescope on the Hinode satellite), and involves programming in Python and IDL. Depending on the interest of the student, numerical modeling in collaboration with colleagues from Oslo is also a possibility.

Diagnostic of solar eruptive prominences

Supervisors: Dr Nicolas Labrosse and Prof Lyndsay Fletcher

2010-06-13 prominence eruption

Evolution of the 2010-06-13 prominence eruption.

Solar prominences are large magnetic structures confining a cool plasma in the hot corona, surrounding a polarity inversion line in the photospheric magnetic field. Once prominences are formed, they can remain stable for over a solar rotation and 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.

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 (e.g. from Hinode, STEREO, SDO, IRIS, or Solar Orbiter), and observations from ground-based observatories (e.g. ALMA, THEMIS, DKIST).

The ionisation degree of solar prominences

Supervisors: Dr Nicolas Labrosse and Prof Lyndsay Fletcher

SDO/AIA images of a filament on the sun from August 31, 2012. From upper left and going clockwise: 335, 171, 304 and 131 Å channels

In this project, the selected PhD student will work with the project supervisors to carry out new radiative transfer calculations of the plasma ionisation degree in solar prominences and filaments, which are among the most spectacular phenomena produced by the Sun’s magnetic field in the solar atmosphere. The student will also analyse data from combined observations of prominences and filaments between observatories from the ground (e.g. ALMA, DKIST) and from space (e.g. Hinode, AIA, IRIS, Solar Orbiter). The student will compare these observations with computed intensities of spectral lines formed over a wide range of temperatures.
The project’s expected outcomes are: a better understanding of the ionisation degree in solar prominences, and ultimately of the thermal structure of the prominence plasma and its coronal environment; open-access numerical data on ionisation degree accessible to observers and modellers to use in their research.

Structure and dynamics of tornado-like prominences

Supervisors: Dr Nicolas Labrosse and Prof Lyndsay Fletcher

A tornado observed on 2014-07-15 by SDO/AIA at 171 Å.

A tornado observed on 2014-07-15 by SDO/AIA at 171 Å.

The existence of tornado-like prominences (‘tornadoes’) is one of the major puzzles of our understanding of the solar corona. Observations from the EUV to the infrared reveal complex plasma motions which are difficult to interpret due to projection effects and lack of information about the magnetic field supporting the plasma. These dynamic structures are often associated with prominence legs (above the solar limb) or filament barbs (on the solar disk). They’ve also been associated to prominence eruptions. They represent essential case studies for deepening our understanding of the Sun’s corona.

A goal of this project is to examine the temperature, density and velocity of the plasma for several well-observed tornadoes using multi-wavelength data, and to identify the mechanisms responsible for the observed shapes of optically thick line profiles in UV and EUV by comparing them with those computed from 2D NLTE radiative transfer models. Another goal is to examine the association with prominence eruptions and identify which mechanisms may be responsible for triggering the eruption.

The student will work on EUV-UV-optical-submm imaging and spectroscopy of tornado-like prominences, and on Non-LTE radiative transfer modelling of tornado-like prominences. The student will hereby develop advanced knowledge of solar prominence physics, spectral line formation, radiative transfer modelling, solar data analysis and solar spectroscopy.

Diagnostics of solar particle acceleration – a cosmic prototype

Supervisors: Prof Eduard Kontar, Dr Iain Hannah and Prof Lyndsay Fletcher

NASA's RHESSI Solar X-ray telescope

NASA’s RHESSI Solar X-ray telescope

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. We were the UK Co-I Group on the NASA high energy RHESSI solar mission and involved with ESA’s Solar Orbiter mission, Glasgow is involved in a wide range of theoretical and numerical projects on diagnosing data on solar electron and ion acceleration.

Possible thesis topics include:

  • data mining and reduction;
  • signal analysis (spectrum and image deconvolution);
  • tests of phenomenological models against data;
  • numerical simulations and analytic modelling

Particles, Plasma and Electromagnetic Waves in the Heliosphere

Supervisors: Prof Eduard Kontar and Prof Lyndsay Fletcher

LOFAR - The Low Frequency Array for Radio astronomy

LOFAR – The Low Frequency Array for Radio astronomy

The physics of the solar system plasma in the near-Sun environment and further into space – the heliosphere – is studied by means of in-situ observations of particles and fields and low frequency radio emission and supported by theoretical calculations of the plasma wave, wave-particle and particle transport processes that link the Sun to space.

We have close involvement with instruments and missions designed to study the heliospheric environment and can offer a range of theoretical projects, with supporting observations, e.g.:

  • Physics of wave-wave and wave-particle interaction in the heliosphere
  • Wave acceleration of particles in solar flares
  • Coherent plasma emission from energetic particles, plasmas and shock waves
  • Development of solar radio emission models for the next generation of solar radio observatories (e.g. LOFAR – The Low Frequency Array for Radio astronomy, and FASR – the Frequency Agile Solar Radio telescope)

Studying the energetics of small solar flares

Supervisors: Dr Iain Hannah NuSTAR, XRT and AIA

Solar flares are rapid releases of energy in the solar atmosphere and the energetically smaller the flare the more frequently they occur. These microflares, and heading down to the postulated nanoflares scale (about a billionth the energy of the biggest flares), could contribute significantly to the heating of the solar atmosphere. If these small events involve the same physical process as the large events then they should also accelerate particle as well.

Projects studying these small flares require highly sensitivity observations of the Sun’s atmosphere and recent work has used the unique X-ray observations from NASA’s astrophysics telescope NuSTAR in comparison to data from solar X-ray/EUV /UV telescopes like Solar Orbiter/STIX, Hinode/XRT, SDO/AIA and IRIS.

Pulsar Magnetospheres

Supervisor: Prof Declan Diver

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 project will be concerned with:

  • developing simulations of the interaction between fast particle streams and large-amplitude collective oscillations;
  • extending our analytical attack on relativistic Landau damping, and exploiting the new physics that arises; and
  • creating the necessary relativistic transformations that allow the radiation field to be translated into the observer’s frame.

Cosmic Magnetism and Plasma Cosmology

Supervisor: Dr Declan Diver

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, and (2) the development of density structure in large-scale mixed flows of plasma and neutrals.

  • Self-guiding magnetic fields, 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 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
  • 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

Plasma Sheath stability and plasma acoustics

Supervisor: Prof Declan Diver

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.

  • In plasma acoustics, the ion wind and localised heating of a plasma source in a neutral gas can trigger significant sonic disturbances.
  • In the sheath stability studies, the electrostatic environment at the perimeter of a possibly deformable conducting (or dielectric) structure placed directly in a flowing 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.

Surface flow induced ionization in the Sun

Supervisor: Prof Declan Diver

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,
  • the investigation of 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 processes on solar cycle timescales

Self-consistent dust growth in plasmas

Supervisor: Prof Declan Diver

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, there are fewer investigations of the more profound problem of growing the dust from first principles directly in the plasma.  Classical condensation mechanisms 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.
The main aims of this project are:

  • To model the formation and evolution of dust in the original supporting plasma;
  • To examine the electrostatic charging of dust over a range of scales, and its subsequent growth, with and without a magnetic field
  • To simulate the remote diagnosis of the medium

To discuss further your interests, please contact group members directly with any questions.