PhD projects

Supervisor: Dr Rebecca Bowler

Contact: Rebecca Bowler

Project description: A detailed view of the first galaxies with a multi-wavelength approach*

At the cutting-edge of Astronomy research is the study of the formation and evolution of the first galaxies. Through breakthrough observations in the past 30 years it has been possible to identify galaxies from when the universe was less than 500 million years old. These galaxies have unusual properties compared to the local universe, showing low chemical enrichment and dust obscuration, and irregular morphologies.

A key challenge when attempting to understand the properties of such galaxies is that the majority of known sources are extremely faint and barely resolved by current and future facilities (e.g. HST and even with JWST). This project will focus on understanding in detail the properties and formation mechanism of a sample of rare, luminous/massive sources found in the distant universe. These galaxies are unusually bright, which makes them laboratories to study over the full electo-magnetic spectrum, and are spatially resolved with Hubble and other facilities. Furthermore there is evidence for a complex structure with dust obscured regions, fully dust obscured companions and tentative signatures of active galactic nuclei [1, 2, 3].

The project will likely utilise a range of data from cutting edge observations from JWST, deep spectroscopic data from VLT-MOONS and/or radio observations from the MIGHTEE and ALMA facilities to provide a unique insight into how galaxies form and evolve in the first few billion years.

Data:

• JWST data
  
• MOONS
• ALMA
  
• MIGHTEE

* This project has dedicated funding

Supervisor: Dr. Phil Bull

Contact: Phil Bull

Project description: Unveiling Cosmic Dawn with the Hydrogen Epoch of Reionization Array*

Cosmic Dawn - the time when the first stars and galaxies switched on - remains shrouded in mystery. While challenging to observe using optical and near-infrared telescopes due to the rareness and obscuration of bright sources, a series of radio telescopes (like HERA, the Hydrogen Epoch of Reionization Array, in South Africa) are being constructed that have the sensitivity to detect the presence of large amounts of neutral hydrogen during this epoch, via the 21cm emission line. This will allow us to map the neutral gas surrounding the first bright sources and understand how rapidly they reionised the Universe.
 
HERA is a large interferometric array that will have up to 350 receiving elements when fully completed. It is being built in stages, and has already collected several seasons of data in a smaller configuration with between 50-100 receivers. Recent analyses of early seasons have produced the best upper limits on the power spectrum of 21cm fluctuations from the Cosmic Dawn and Epoch of Reionisation to date (see https://arxiv.org/abs/2108.02263), with significantly larger volumes of data well on the way.
 
In this project, you will develop and hone a set of advanced statistical analysis tools to recover the 21cm power spectrum from the available HERA data despite the presence of much brighter contamination ("radio foregrounds") and systematic effects due to the complexity of the instrument. These tools are based on a variety of techniques for high-dimensional Bayesian inference, a type of machine learning. Through this project, you will develop a mix of skills, including some analytic theoretical work on statistics, hands-on data analysis with a large, cutting-edge astronomical dataset, and high-performance computing, which may include some GPU programming. The student will be able to choose which of these areas to put more emphasis on.

* This project has dedicated funding

Supervisor: Dr. Rowan Smith

Contact: Dr Rowan Smith

Project description: Magnetic Zooms: Testing how magnetic fields shape galaxy structure and star formation

Magnetic fields pervade galaxies. They trace the interstellar medium and provide an important source of pressure support against gravity that will slow the process of transforming gas into stars. Understanding how fields evolve, and their true dynamic importance is still an unresolved question, but it is crucial for our understanding of both galaxy evolution and star and planet formation. In this project we will use some of the highest resolution simulations of galactic magnetic fields ever performed and zoom into even more detail to investigate how magnetic fields affect the formation of cold molecular clouds of gas, the efficiency with which they form stars, and the distribution of stars within them.

In this project you will use the DiRAC supercomputing facility to carry out advanced HPC simulations as part of the P.I’s “Zooming into Star Formation” thematic project. Data analysis will be mainly carried out in python, using scripts already written within the group, but also developed by the student. Our results will then be critically compared with observations from the SOPHIA FIELDMAPS survey, polarised dust maps, and HI observations. Some knowledge of basic programming, particularly in python, would be desirable but training will be provided as part of the PhD.

Supervisor: Dr. Rowan Smith

Contact: Dr Rowan Smith

Project description: Revealing the structure of nearby galaxies in the JWST Era

With the advent of JWST, the structure of the gas and dust in nearby galaxies has been revealed as never before. It is now possible to study the interstellar medium in detail and investigate how stars are formed in other galaxies outside our own as was only previously possible in the Milky Way. To probe the physics revealed by such observations, similarly detailed theoretical models and predictions are needed to test them. In this project we will take the high-resolution CLOUDFACTORY galaxy simulations performed by our group and contrast them with the results from the PHANGS collaboration (of which the supervisor is a member) surveys of nearby galaxies using the JWST telescope and the ALMA facility. Care will be taken to analyse both the simulations and observations using the same methods, and so this project is ideal for a student who is interested in both theoretical and observational aspects of Astrophysics. The end goal is to test whether the gas structure of other galaxies is compatible with our understanding of the Interstellar Medium (ISM) developed from our own Milky Way and to use the external viewpoint to gain big-picture insights into the matter cycle of galaxies. Points of comparison will be the formation of dense filamentary structures in the ISM, disruption of gas by massive feedback bubbles, using radiative transfer to diagnose the density distribution of gas clouds, and relating large-scale galactic features such as spiral arms and spurs to star formation. There is scope within the project to focus more on different aspects of these depending on the interests of the student.

Supervisory Team: Prof. Clive Dickinson, Dr. Paddy Leahy, Dr. Stuart Harper

Contact: Clive Dickinson

Project description: C-Band All-Sky Survey

The C-Band All-Sky Survey (C-BASS) is a dedicated 5 GHz all-sky radio survey, that is mapping the entire sky in intensity and polarization, with an angular resolution of 45 arcmin (https://cbass.web.ox.ac.uk/home). The data will be crucial in understanding and removing of diffuse polarized synchrotron radiation from sensitive CMB surveys that are aiming to detect gravitational waves from the early Universe. The maps are also of great interest for studying the Galaxy, including emission mechanisms, Galactic structure, the Galactic magnetic field.

C-BASS has completed the northern survey observations taken at Owens Valley Radio Observatory in California. The maps are currently being finalised with a number of initial scientific exploitation papers being prepared. The southern survey, located near to the SKA site in the Karoo desert, South Africa, is currently being commissioned. The data from the southern telescope is expected to available in 2023. Eventually, we will produce full-sky maps that will be released to the astronomical community (2025/2026). In the mean time, we can use these new data to study Galactic emission. For example, C-BASS data will allow a much better separation of CMB/foregrounds in the WMAP/Planck satellite data. A number of science papers are expected to come from C-BASS (see e.g. https://cbass.web.ox.ac.uk/journal-papers).

The student project will be to take a lead in the data analysis and scientific exploitation using C-BASS data. A major task will be in reducing and calibrating the southern data as it comes in (experience with Python and/or CC++ would be an advantage). Understanding the data will be crucial for ensuring that scientific results are not affected by residual systematic errors in the data, such as from ground emission and radio frequency interference (RFI). There will be ample opportunity to do scientific analyses of C-BASS data in conjunction with multi-frequency data, depending on the interests of the student, which will lead to peer-reviewed journal papers.

C-BASS is a collaboration between Manchester and Oxford Universities in the UK, Caltech/JPL in the U.S., Rhodes University/UKZN in South Africa, and KACST in Saudi Arabia.

Supervisory Team: Prof. Michael Brown, Prof. Richard Battye, Prof. Jens Chluba, Prof. Lucio Piccirillo

Contact: Michael Brown, Richard Battye, Jens Chluba, Lucio Piccirillo

Project description: Probing the Early Universe with Simons Observatory

Simons Observatory (SO) is a next-generation Cosmic Microwave Background (CMB) telescope to be located in Chile. Its primary objective is to make high fidelity images of the Cosmic Microwave Background which will allow constraints on fundamental physics. The University of Manchester leads a recently-announced major UK contribution to SO (termed SO:UK) which will have a major impact on SO’s ability to pursue this headline science goal. The UK team will provide: (i) two additional state-of-the-art telescopes for SO, (ii) a UK-based data centre for processing the large data volumes and (iii) a program of algorithm development aimed at turning the raw data from the ~80,000 detectors into higher-level data products and scientific results. The JBCA at The University of Manchester hosts the data centre and is delivering one of the two SO:UK telescopes. We are also playing a major role in the pipeline development work. As part of our group you will have the opportunity to get involved with this state-of-the-art CMB experiment in multiple areas including contributing to the instrument development, developing data processing algorithms and in the scientific exploitation and interpretation of the data. There are three PhD projects available to work with the SO team at the JBCA which will be between 10 and 15 scientists. Each will become part of the team taking a general interest in the overall project, but will also have specific responsibilities. Projects B & C should expect real SO data on the timescale of the PhD, while the delivery of the SO:UK SATs involved in project A is due during the timescale of the PhD.

* Project A: (Piccirillo and Brown)

This will be a technical project involving the build of the two SO:UK telescopes. Our group is in charge of the build and operation of a state-of-the-art telescopes dedicated to the observations of the CMB. It will be a vital part of the most sensitive experiment ever built in experimental cosmology. The student will play a major role in the assembly, testing and operations of the telescope first in the testing site at Jodrell Bank Observatory and then at the observing site in Atacama (Chile).

* Project B: Constraining primordial gravitational waves (Brown and Battye)

One of SO's primary goals is to detect a very specific pattern in the polarisation of the CMB radiation (termed “B-modes”) which will provide a unique observational window into the very early Universe and physics at GUT-scale energies. These B-modes can be created by primordial gravitational waves, but also by other non-standard physics such as birefringence. These signals are typically very weak and it will require exquisite control of systematics. The project will involve some work on the data pipeline working with the data centre staff , development of sophisticated mathematical algorithms to remove systematic effects and playing a role in the international SO working group on B-mode science.

* Project C: Using the Sunyaev-Zeldovich effect to constrain fundamental physics (Battye and Chluba)

The SZ effect is the inverse Compton scattering of CMB photons by the gas inside galaxy clusters along the line of sight. It has a unique spectral signature and it has been used to constrain cosmological parameters such as the matter density, the amplitude of perturbations and others including the properties of dark energy and neutrino masses. This is done using observables such as the number of clusters a function of redshift and the power spectrum fo the Compton y-parameter. The JBCA plays a significant role in the SZ working group. The objective of the PhD will be to work on the modelling of the SZ effect, which involves numerical simulations, modelling the observations and ultimately using the results to constrain cosmological models and the underlying astrophysics of clusters.

Supervisory Team: Prof. Ben Stappers, Dr. Inés Pastor Marazuela, Dr Kaustubh Rajwade, Dr Manisha Caleb

Contact: Ben Stappers

Project description: Studying Fast Radio Bursts with MeerKAT

Fast Radio Bursts (FRBs) are currently one of the most  exciting and mysterious sources in astronomy. They are millisecond-long bursts of radio emission which are coming from sources that are distributed throughout the Universe: seen in our near neighbour galaxies and all the way to at least redshift 2. This combination of a burst of radio emission and large distances mean that they are excellent probes of the intervening medium and so can be used to investigate questions about the  location and nature of the missing baryons and the material around, and within, galaxies. While many hundreds of these sources are now known, the origin is still unclear. Some FRBs are known to repeat, but apparently not all do. So is there more than one type? Proposed progenitors range from highly magnetised neutron stars to the merger of neutron stars. In this project you would be part of the MeerTRAP team which are discovering FRBs using the SKA-precursor telescope called MeerKAT located in South Africa.  MeerTRAP  is discovering FRBs out to at least redshift 2 and is now able to localise these bursts and thus find their host galaxies. You would be involved in the search for these FRBs, studying their emission properties and also looking at the population.

Supervisory Team: Dr. Paddy Leahy (primary), Prof. Anna Scaife (secondary)

Contact: Paddy Leahy

Project description: Probing the Galactic magnetic field with POSSUM

Our Galaxy’s magnetic field plays an important role in the interstellar medium, sometimes dominating the local dynamics and rarely negligible. It helps regulate star formation and accelerates some particles to relativistic energy, forming cosmic rays. These processes are not fully understood, and nor is the structure of the magnetic field, which is often described as turbulent although some organized patterns can also be discerned. There are many observational tracers of the interstellar field, but they all have severe limitations, and so we must make progress by using observational clues to guide theoretical and computational modelling.
 
One of the most important magnetic tracers is Faraday rotation: the plane of polarization of radio waves change with wavelength, at a rate proportional to the integral the magnetic field component along the line of sight, weighted by the free electron density. This can be relatively easily assessed using extragalactic radio sources, which give us the integrated Faraday rotation along the sight line through the Milky Way. Mapping this across the sky gives a weighted 2D projection of the 3D magnetic pattern. The quality of this information is about to be vastly increased by the Polarization Sky Survey of the Universe’s Magnetism (POSSUM), an international project to measure the polarization of radio sources across most of the sky at 800-1088 MHz, using the Australian SKA Pathfinder (ASKAP), which will give a 10-fold increase in sampling of the Faraday rotation pattern.  In addition to extragalactic sources, POSSUM will detect polarization from synchrotron emission in the interstellar medium, which in principle gives more direct information about the 3D field structure, although there are challenging instrumental issues that have to be overcome.
 
The aim of this PhD project is to study the statistical structure of the Faraday rotation and the underlying magnetic field. The primary observational input will be the POSSUM Faraday results: about one quarter of the sky will have been observed in time to use,  including fields close to the Galactic plane with a long sight-line through the disk, and at high latitude where we are looking just through the local layer of the Galaxy. You will draw on other observational results as needed, for instance single-dish observations of the Galactic synchrotron emission at short wavelengths, where the polarization traces the field component in the sky plane. You will interpret your results using theories ranging from toy models that can be run on a laptop to the outputs of massive full-disk magneto-hydro-dynamic simulations being run by Rowan Smith and collaborators.

Supervisor: Prof. Christopher Conselice

Contact: Christopher Conselice

Project description: Discovery and Study of the First Galaxies and Stars with the James Webb Space Telescope.

Since its launch in late-2021 the James Webb Space Telescope has started a revolution in our understanding of the first galaxies and stars formed within 500 million years after the Big Bang. This update to the Hubble Space Telescope will observe for the first time the birth of galaxies in the universe.  We will also observe some of the earliest stars when they explode as supernova and those seen as gravitationally lensed objects. I am co-leading a JWST guaranteed time observations (GTO) team who will obtain some of the earliest data from JWST for this project, in which these first galaxies and stars will be located and studied.
The student working on this project will lead the discovery of the first galaxies, and studying their properties including their masses, sizes, structures, and merger histories. We are currently obtaining ancillary data with the Hubble Space Telescope and the Very Large Telescope (VLT) in Chile. The student working on this project will take on a leadership role in investigating the stellar populations, ages, structures, and star formation rates of the first galaxies and stars using JWST imaging and spectroscopy. These observations will be interpreted in terms of theories of galaxies formation to test and exclude different ideas for how the first generations of galaxies and star formed.

Supervisory Team: Prof. Mike Garrett (UoM) and Prof. Andrew Siemion (UCB & UoM).

Contact: Mike Garrett

Project description: Looking for anomalies in astronomical data (Technosignatures) as evidence of extra-terrestrial intelligence.

For untold millennia, humankind has looked up at the sky and marvelled at the vastness and beauty of the cosmos. Countless generations have tried to understand their place in the centre of these immensities while contemplating the meaning of life and their own individual mortality. The scientific method has revealed some of the inner workings of the universe, and yet there are some fundamental questions that remain unanswered. One of these is: Are we alone? This PhD project aims to look for the kind of artificial signatures an advanced technical civilisation might imprint on astronomical data collected by telescopes on Earth and in space. A general goal is to search for generic anomalies in astronomical data by utilising large-scale public telescope surveys, looking for unusual features in multi-waveband data e.g. narrow-band coherent signals in the radio and “waste heat” manifesting itself as an excess in the IR.  We will also further develop SETI searches using the technique of radio interferometry – this offers several advantages compared to traditional single-dish or beam-formed approaches, and we will do this in collaboration with the Breakthrough Listen Initiative (BLI), specifically contributing to the BLI MeerKAT 1-million star survey, preparing the way towards SETI with the Square Kilometre Array (SKA).

Supervisor: Dr. Eamonn Kerins

Contact: Eamonn Kerins

Project description: Space-based exoplanet detection with microlensing

Microlensing is proving to be the most capable method to find cool low-mass planets, including planets around the most common types of star, and planetary architectures that most resemble that of our own solar system. The demographics of these planets is also crucial for testing planet formation theories.

In the next few years NASA will launch the Nancy Grace Roman Space Telescope (Roman) which will undertake a dedicated exoplanet microlensing survey. With a field of view 100 times greater than the Hubble Space Telescope and a data rate more than 20 times that of JWST, Roman will revolutionize our understanding of exoplanet demographics. The ESA Euclid mission may also undertake an exoplanet microlensing survey.

Manchester has developed the Galactic microlensing simulation framework that underpins the design of potential surveys for both Roman and Euclid. A PhD project is available to further develop this simulation framework to enable detailed optimization and analysis work that will be required for both missions.

The project will be computational in nature, both using existing codes and developing new ones. We have a dedicated 64-core AMD Threadripper machine dedicated to our exoplanet work. The exoplanet group working with Kerins currently comprises 5 PhD students and one MSc student. It is expected that this project will involve working closely with colleagues based in France and the US.

Supervisor: Prof. Scott Kay

Contact: Scott Kay

Project description: Next generation hydrodynamic simulations of galaxy clusters

Galaxy clusters host the most massive galaxies in the Universe, with stellar masses up to one trillion times the mass of the Sun. These galaxies are surrounded by huge reservoirs of hot, X-ray emitting plasma, with temperatures over 10 million Kelvin. A puzzling observation, however, is that this gas is not cooling down and forming new stars at the expected rate - why does star formation shut down in massive galaxies? One, currently favoured, answer is that the gas is being kept hot by an active galactic nucleus (AGN) through the emission of powerful jets of radio-bright relativistic plasma. The AGN, powered by accretion on to a super-massive black hole, is energetically capable of counteracting the radiative losses in the X-ray gas and can even drive some of the gas out of the system altogether.
 
Modern hydrodynamic simulations of galaxy clusters attempt to include the effects of this so-called AGN feedback process and can successfully model the shut-down of star formation in brightest cluster galaxies, while producing black holes with observationally-reasonable masses. However, these simulations currently struggle to reproduce the X-ray thermal properties of the gas, predicting material that tends to be too hot and diffuse in the cluster core. Such a discrepancy is likely the result of current models not capturing all the essential physics but may also be due to insufficient numerical resolution.
 
In this PhD project, the student will join ongoing collaborative efforts to develop a new generation of cluster simulations with improved resolution and physics modelling using the SWIFT hydrodynamics code (swift.dur.ac.uk). They will work on science projects involving the analysis of new simulation data as well as have the opportunity to help develop and test new simulation models. The student will join the Virgo consortium and use the DiRAC high performance computing facility (dirac.ac.uk).

Supervisor: Dr. Laura Wolz

Contact: Laura Wolz

Project description: HI Intensity Mapping with MeerKAT

A key goal of cosmology is to understand the accelerated expansion of the Universe, believed to be driven by a force called Dark Energy. Mapping the distribution of galaxies throughout the Universe’s lifetime can measure the expansion history and help us understand the nature of Dark Energy. Historically, cosmologists have successfully used the optical emission of stars located in galaxies to map the cosmic web over time. In the past decade, a new method called intensity mapping has emerged which uses the radio emission of gas (specifically the highly abundant Neutral Hydrogen gas) to trace the galaxy distribution. The future Square Kilometre Array (SKA) and its pre-cursor MeerKAT are enormous radio telescope arrays, capable of higher sensitivities and spatial resolution than any existing radio instrument. Intensity mapping is a unique probe, as it can be observed using the SKA as a single dish array, as well as in interferometric mode which gives much higher spatial resolution in the data. Both datasets are essential if we aim to acquire a complete understanding of how hydrogen traces dark matter and how gas and galaxies evolved with cosmic time.

PhD projects are available to work on the on-going MeerKAT data analysis, both in Single Dish as well as in interferometric mode, as well as the simulation of data including instrumental effects. Topics for exploration include optimisation of the HI and cosmology constraints by combining information from both data types, improvement of the data reduction pipelines as well as preparations and forecasts for SKA observations. Most project work will be computationally and the student will work within the teams of MeerKAT and SKA intensity mapping. Some background reading can be found here https://arxiv.org/pdf/2010.07985.pdf and https://arxiv.org/pdf/2206.01579.pdf.

Supervisor: Prof. Richard Battye

Contact: Richard Battye

Project description: Searching for axions using neutron stars

Axions are one of the leading dark matter candidates and can be converted into photons in the magnetosphere of neutron stars. This can lead to a spectral line signature in the radio/mm waveband. In recent times we have developed techniques to predict the signal expected and have been applying these to observations made by the JVLA and Lovell Telescopes.

The aim of the project - which would likely involve collaboration with scientists in Louvain and Munich as well the JBCA pulsar observers - would be to refine these predictions, involving modelling axion electrodynamics in the magnetosphere, and compare to the most update to date observations. It will require a range of theoretical, numerical and data analysis related skills. At its most optimistic it could lead the detection of the dark matter axions, but more likely stringent upper bounds on their coupling to photons. It could also lead onto a study of the theoretical models for the production of axions.

Supervisor: Prof. Richard Battye

Contact: Richard Battye

Project description: Topological defects at the electroweak phase transition

Topological defects can be formed at cosmological phase transitions where the vacuum manifold has non-trivial homotopy.  The objective of this project is to explore the possibility that topological defects might be formed at the electroweak phase transition in extensions of the Standard Model of particle physics. We have bene studying the so-called two Higgs-Doublet model (2HDM) which is one of the most popular extension with Prof Apostolos Pilaftsis in the Manchester Particle Physics group.

The project will involve further developing the work often using large-scale computing resources based in the Manchester and elsewhere in the UK. It will also develop the picture of cosmological evolution of such defects, and also consider how such a defect might be produced in a particle accelerator such as the LHC.

Supervisory Team: Prof. Gary Fuller & Prof. Danielle George (Department of Electrical & Electronic Engineering)

Contact: Gary Fuller

Project description:  Pushing the Noise Limit: Low Noise Amplifiers for Radio Telescopes

Low noise amplifiers (LNAs) are critical components of receivers for radio telescopes. They offer a number of important advantages over competing
technologies such as operating at 20K rather than 4K as well as being better suited for use in large scale imaging array receivers. Recent advances in
technology have allowed the development of LNAs which operate at much higher frequencies than previously possible.

This is an opportunity to join the Advanced Radio Instrumentation Group in the Departments of Physics & Astronomy and Electrical & Electronic Engineering. 

There are four possible areas of research:

1) The designing and testing high performance, wide bandwidth,
LNAs at frequencies of up to 300 GHz, and beyond, for use in both single pixel and array receivers on the world’s biggest telescopes.
2) The design and construction of receivers for current radio telescopes using new generation, high performance LNAs.
3) New processes and materials for transistors for future, high performance generations of LNAs.
4) Computer-aided LNA design optimisation.

In each of these areas there is the possibility of placements at various collaborating international institutions, including ESO in Germany and Bologna in Italy.  

Supervisory Team: Prof. Gary Fuller & Prof. Philippa Browning

Contact: Gary Fuller

Project description: Modelling time domain radio emission in the circumstellar regions of protostars

Understand how a forming star acquires its final mass is a fundamental issue for a building a comprehensive model of star formation.  The time-dependent and transient nature of the process of mass accretion from the circumstellar disk to the protostar is difficult to study and poorly understood. However, this process can be diagnosed through variable emission it produces. Recently, we have developed new idealised models (Waterfall et al Mon Not Roy Astr Soc 483, 917, 2019; Waterfall et al. Mon Not Roy Astr Soc 496, 271, 2020) of this phenomenon in T-Tauri stars, in which magnetic large loops interconnecting the star and the accretion disk are filled with non-thermal electrons due to magnetic reconnection which emitting at radio wavelengths.

The aim of the current project will be to develop more sophisticated and realistic models of this process and predict its radio emission. This will be done using numerical resistive magnetohydrodynamic simulations of protostars, which will predict the energy release due to magnetic reconnection as the stellar magnetic field interacts with the disk.  Then, the gyrosynchrotron radio emission due to electrons accelerated by the reconnection – similarly to solar flares – will be calculated, modelling both the intensity and polarization properties as a function of frequency as the accretion event progresses.

Comparison of the results of these models with observations will provide some of the first insights on this final stage of accretion on to protostars. The results will provide important constraints on the design the first large scale radio surveys of star forming regions with the world’s largest radio telescope, the Square Kilometre Array (SKA) and there may be the opportunity to be involved in the comparison of the model predictions and observations made with current radio telescopes.

Supervisory Team: Prof. Gary Fuller & Dr. Rowan Smith

Contact: Gary Fuller

Project description: The Role of Magnetic Fields in the Formation of Massive Stars

Magnetic fields are ubiquitous in the interstellar medium but their detailed role in the formation of stars is as yet unclear. In the dense star forming regions of molecular clouds the magnetic field can be traced through observations of the polarized continuum emission from dust grains which align with the magnetic field. However, to understand how magnetic fields affect the evolution of the gas, observations of the magnetic field must be combined with observations of the cold, molecular gas in the regions. This project will study the impact of the magnetic fields as gas flows from parcsec-scale clumps down to individual star forming cores and protostars. It will involve observations of polarization emission from dust and molecular lines to study the magnetic field and molecular gas covering a wide range of size scales in star forming regions. Part of the project will be developing new methods to compare the polarization and line observations with the results of state-of-the-art magneto-hydrodynamics simulations.  This work will be carried out in part as part of the follow-up of ALMAGAL, the ALMA large programme studying the formation and evolution of high mass stars and the ERC Synergy project ECOGAL.

Supervisory Team: Prof. Gary Fuller & Dr. Rowan Smith

Contact: Gary Fuller

Project description: ALMAGAL: The ALMA Study of High Mass Protocluster Formation in the Milky Way

Understanding the formation of massive stars is central to wide range of astrophysics, from the star formation history of the Universe to the physical and chemical evolution of galaxies and the origin of blackholes, pulsars and gamma ray bursts. ALMAGAL is an ALMA Large Programme to observe 1000 young, high mass regions to study the formation and evolution of high mass stars and their associated stellar clusters. This project will involve the analysis of the ALMAGAL observations, and observations from related ALMA projects, to study the properties of the sources detected, the dynamics of the regions and their environments, and the evolutionary status of the protostars. ALMAGAL is large international collaboration and there may be opportunities to spend time working at some of the partner institutions. There will also be opportunities to take part in, and potentially, lead follow-up observations of some of the sources studied with ALMAGAL. The results of the analysis of the ALMAGAL observations will be compared with numerical simulations of massive star formation to help constrain the initial conditions required to form the most massive stars.

Supervisory Team: Dr Paddy Leahy, Prof Ian Browne, Prof Peter Wilkinson

Contact: Paddy Leahy

Project description: Is there a new radio background? The L-Band All-Sky Survey (L-BASS)

The aim of the L-BASS project is to map the intensity of the radio sky at ~1.4 GHz with unprecedented absolute accuracy (0.1K) – ten times better than achieved by Penzias and Wilson in their discovery of the cosmic microwave background radiation. There are several reasons to do this, the most exciting being that it should settle a current astrophysical puzzle about the reality of excess all-sky low frequency emission of unknown origin (the “ARCADE-2 controversy”). Such an excess might also help account for another recent controversial result which is the claimed detection of strong absorption arising in atomic hydrogen situated at a redshift of 17 (the “EDGES result”). In addition our sky map will have impact on Galactic astrophysics and our knowledge of the Cosmic Microwave Background.

During the PhD project the student will produce and interpret the first sky maps with the L-BASS telescope system which is situated at Jodrell Bank Observatory. The system, which is based on two large horn antennas, is now up and running. Commissioning observations are in progress. This PhD project involves a mixture of hands-on work to optimize the calibration of the system, making precisely calibrated observations and writing software for data analysis followed by the astrophysical interpretation of the results. To achieve the required accuracy (0.1K) requires particularly careful calibration using a cryogenically cooled reference load of known physical temperature; the assembly and testing of this cryogenic calibration load will take place during the next two years and form a significant part of the project. In two years, the plan is to move the instrument to Tenerife, a site which enable us to map two thirds of the whole sky.

Supervisory Team: Dr Paddy Leahy (primary), Dr Emmanuel Bempong-Manful (co-supervisor)

Contact: Paddy Leahy

Project description: Testing models of relativistic jets with e-MERLIN

Many of the issues in understanding structure formation and black-hole growth are thought to be resolved by suitably-tuned feedback of energy and momentum from AGN activity – from dense to diffuse phases of matter.  Relativistic plasma jets of radio-loud AGNs are particularly thought to be responsible for the production of the most energetic photons and hadrons in the observable Universe, thereby playing a key role in this feedback cycle. However, the physics driving the observed jet structure in these cosmic outflows remains an open question. To resolve them we need to quantify the mass, momentum and energy inputs from jets and to work out how they interact with their environment. 

Here at Manchester we are leading an ambitious global effort  (The e-MERLIN Jets Legacy programme) to resolve these and other key questions in extragalactic jet physics. The programme has been mapping a number of powerful radio galaxies and quasars, allowing us to study for example the detailed structure of magnetic field in relativistic jets (the synchrotron radiation polarisation) and in the foreground gas (via Faraday rotation). Deep LOFAR observations have also been acquired for the programme, providing us with the unique opportunity to probe the dynamics and energetics of relativistic jets over broad frequencies. 

The goal of this PhD project will be to utilize these new radio observations to map the jet structure of some well known powerful radio galaxies in order to test the relativistic beaming model in jets. The student will join the e-MERLIN Jets Legacy collaboration and become a part of the LOFAR-VLBI Working Group. Depending on their interests, the project could be extended into a multiwavelength campaign with complementary observations at optical and X-ray wavebands, and/or perform numerical MHD simulations to model the jet kinematics and compare theory with observations.

Supervisory Team: Prof. Jens Chluba

Contact: Jens Chluba

Project description: CMB Spectral distortion anisotropies as a novel probe of cosmology

Spectral distortions of the cosmic microwave background (CMB) - tiny departure of the CMB energy spectrum from that of an equilibrium blackbody distribution - have now been recognized as one of the important future probes in cosmology and particle physics. While very challenging to observe, multiple experimental activities have started in the cosmology community with the big goal to improve the long-standing limits by COBE/FIRAS from the 1990s by orders of magnitudes. In addition to the average distortion signals in the CMB monopole spectrum, it has now been highlighted that anisotropic spectral distortions can be directly measured with existing and upcoming experiments (e.g., Planck, Litebird, The Simons Observatory, CMB-S4, the SKA). This directly links distortion science to studies of the CMB temperature and polarization anisotropies, and allows us to constrain new physics related to primordial black holes, primordial magnetic fields, axions, cosmic strings and textures as well as primordial non-Gaussianity.

In this project, you will work on the existing cosmological thermalization code CosmoTherm to develop novel tools for predicting and analysing spectral distortions signals (both average and anisotropic) in light of future CMB missions and experiments. This will identify novel methods for studying early-universe and particle physics in regimes that otherwise remain inaccessible. You bring a keen interest in theoretical physics / cosmology and experience with various modern coding languages (e.g., C++ and Python). The specifics of the project are open and multiple exciting possibilities are available, depending on the student's inclinations and strengths.

Supervisory Team: Dr. Patrick Weltevrede & Dr. Mike Keith

Contact: Patrick Weltevrede

Project description: Characterizing the dynamic magnetospheres of neutron stars

Radio pulsars are highly magnetised neutron stars which rotate very rapidly: up to 100s of times per second. During each rotation, the radio emission beamed along the magnetic poles sweeps across the Earth and can be detected by very sensitive radio telescopes as a regular sequence of pulses. The rotation of the neutron stars can be extremely stable which makes them very accurate clocks allowing tests of the general theory of relativity.

However, for most pulsars the individual pulses of the observed sequence vary greatly in shape, intensity and polarization. These variations are caused by largely unknown physical processes in the magnetosphere of these stars. In some cases these variations happen in a coordinated fashion, which are known as drifting subpulses, indicative of regular dynamical changes in the magnetosphere.

In this project you will explore observational data from the "1000 Pulsar Array" project on the MeerKAT telescope in South Africa (a pre-cursor of the SKA: the Square Kilometre Array which will be the largest telescope in the world). This rich data-set has exquisite quality observations for many pulsars yet to be analysed in any detail. In this project you will characterize this variability seen in the pulse shapes and their polarization, and explore the implications for magnetospheric theories.

Where possible, we will supplement this data with observations from the Parkes radio telescope in Australia (a great instrument which has discovered more pulsars than any other radio telescope in the world) and the FAST radio telescope in China (largest single-dish telescope in the world).