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Jodrell Bank Centre for Astrophysics

Jodrell telescope at sunset

Dissertation projects for the MSc by Research in Astronomy and Astrophysics

Below are some of the MSc(R) projects for this coming year. However, we encourage prospective MSc(R) students to speak with as many of our academic staff, as early as possible, to find out what we do and to see if there are possible MSc(R) projects available - this list is unlikely to be comprehensive and research projects can quickly become out-of-date.

Note that supervisors and projects should be decided within the first 1-2 weeks of the first semester and they should inform the MSc(R) course director, Laura Wolz.

Deep learning for image-based outlier detection in radio astronomy

Supervisor: Anna Scaife

Most deep learning applications in radio astronomy currently focus on supervised or semi-supervised classification.

In this project the student will investigate the potential of deep-learning approaches to one-class classification for identifying outliers/anomalies in astrophysical samples, in particular using data from telescopes such as the VLA and LOFAR on radio galaxies. In doing this, the student will take existing models for anomaly detection and adapt them for the domain-specific astronomy problem.

A key element of this adaptation will be considering the form of the loss function and the student will examine a range of existing choices from the literature before investigating the potential of alternative formulations.

Explore the 3d Milky Way

Supervisors: Albert Zijlstra, Iain McDonald

The GAIA satellite is in the process of mapping the precise position and motion of nearly every star in the Milky Way. It is measuring the parallax of every star and uses this to obtain an accurate distance.  The GAIA DR3 catalogue (2020) contains 2 billion stars. An example of its use is at https://youtu.be/BknZ2YxegIk.

The current project aims at creating accurate 3-d HR diagrams (the third dimension being the location in the Milky Way) by deriving the temperature and luminosity for each star it this catalogue. This requires combining available photometry for each star from other catalogues, and fitting model atmospheres to the spectral energy distribution.

The results can be used to identify stars of particular interest, for instance stars with circumstellar dust fro their formation or their final evolution, or the study of interstellar extinction. Depending on the interest of the student, the focus can be on the software development or on the analysis.

Finding the first galaxies in the universe with deep imaging

Supervisor: Chris Conselice

This project will focus on discovering the earliest galaxies that formed in the universe and measuring their basic properties. Astronomers have long sought to find the earliest galaxies in the universe and to use them to determine how galaxies first formed. We can currently see galaxies back to when the universe was around 500 Million years old. We are however still learning about these galaxies and their basic properties such as their masses, sizes, and luminosities.

This project will use new data to search for and locate massive galaxies in the first billion years of the universe's history using new deep ground-based and Hubble Space Telescope imaging.  The project will involve using this imaging to discover these systems and then to make catalogues of objects.  From this it will be possible to measure the masses of these galaxies and their number densities, putting constraints on the formation and galaxies and their role in the evolution of the universe.

Once we have identified the candidate distant galaxies using the catalogues available, the student will characterise them in terms of the number of galaxies, their sizes, star formation rates, and masses.  From this data, we can compare with theory to determine the processes driving the earliest galaxy formation.

This project can be done with a computer using Matlab or preferably python coding.

Gravitational lensing

Gravitational lenses are systems in which a background object is multiply imaged by the action of the gravitational field of a foreground galaxy. Gravitational lensing is important because it allows us magnified views of distant objects in the Universe, and also because it allows us to investigate mass distributions in galaxies independent of their light emission.

We are currently involved in a number of projects with major radio facilities (e-MERLIN and LOFAR) and planning for future surveys, including Euclid. Accordingly, there are a number of areas in which students could become involved:

  • We are conducting LOFAR observations of a number of gravitational lenses to explore the properties of lensing galaxies. Because lenses give us multiple lines of sight through the galaxy, this allows us to deduce the effect of the lensing galaxy on the radio signal that propagates through it.

  • We are currently conducting a survey called LBCS which provides calibrators for the analysis of the long baselines of LOFAR, which use the international stations outside the Netherlands. There are opportunities to get involved with the development of interferometric pipelines for the reduction of LOFAR-LB data.

  • We have a number of projects involving radio observations of both radio-loud and radio-quiet lenses in order to study both lensing galaxies and the lensed sources (the latter are visible thanks to the magnification of the lensing galaxy).

  • We are involved in a science working group of Euclid which is investigating the use of Euclid-discovered gravitational lenses for the study of galaxy evolution. The student will assist with the simulation of the scientific output from such a survey.

Impact of RFI on the cosmological HI intensity mapping signal

Supervisors: Laura Wolz and Keith Grainge

Intensity Mapping of the Neutral Hydrogen gas (HI) is a new cosmological survey type to observe the matter  distribution. It uses the integrated 21cm emission of the HI gas in the radio wavelength to map the largest scales of the matter distribution with radio telescopes. The resulting HI intensity maps trace the underlying structure and therefore can be used to test cosmology, for example, by measuring the expansion rate of the Universe via Baryon Acoustic Oscillation (BAO) detection.

The South African Square Kilometre Array pathfinder MeerKAT is an interferometric array consisting of 64 dishes, which can be used in so-called single dish mode for HI intensity mapping observations. There are many observational challenges to overcome in order to detect the HI signal, such as subtracting astrophysical foregrounds and terrestrial radio frequency interference (RFI). In this project, we will examine the RFI present in the pilot HI intensity mapping data from MeerKAT in order to understand its statistical properties. We will then model the RFI in telescope simulations and test different methods to subtract them.

We will investigate the impact of the RFI properties and removal methods on the resulting HI intensity maps and the cosmological constraints.

Some programming experience in python or similar is essential, background in radio astronomy desirable.

Looking for the techno-signatures of advanced technical civilisations via anomalies in astronomical data

This project will search for anomalies in publicly available astronomical data that may be generated by the activities of an energy-intensive extraterrestrial civilisation. These so-called "techno-signatures" may take various forms but we will focus on unusual excess emission in the infrared domain due to the generation of waste-heat, in addition to other outliers e.g. discrepancies in spectroscopic v astrometric distances, excess stellar emission in the radio domain etc.

It may be possible to introduce some Machine Learning and AI aspects into the project. We will choose a well-defined topic with the aim of publishing the results in a refereed journal (see: Extending the Breakthrough Listen nearby star survey to other stellar objects in the field for a recent example).

Prior knowledge: it would be useful if the student has some background in astronomy and astrophysics but this is not essential. The student should be prepared to use software tools to interrogate large astronomical data sets, and to write python scripts to analyse the data.

Rotation measure structure of large DRAGNs in POSSUM Pilot II

Title: Rotation measure structure of large DRAGNs in POSSUM Pilot II

Supervisor: Dr Paddy Leahy 

POSSUM is one of several surveys being conducted with the ASKAP telescope, which is revolutionary in that it is the first aperture synthesis telescope equipped with “PAFs”, essentially the radio equivalent of a CCD chip. This gives it a very large field of view for a high-frequency telescope, about 36 square degrees, about 150 times more sky area than visible to the VLA at any one time. This makes it ideal for large, deep radio surveys, and POSSUM will cover 75% of the sky, in full polarization and over a 300 MHz bandwidth. POSSUM is an international project and is currently in its pilot phase. Its aim is to measure Faraday rotation, which depends on the magnetic field between the radio source and the Earth. There are all sorts of specific science goals but this MSc project is to study the magnetic field immediately surrounding the radio lobes of radio galaxies.  These lobes are bubbles of relativistic plasma embedded in the 100-million kelvin gas that surround galaxies, especially in clusters of galaxies. We can isolate the magnetic fields in this gas from the rest of the line of sight because the field direction and strength, and hence the amount of Faraday rotation, varies with position across the lobes. The best targets are the radio lobes with largest apparent size, > 5 arcmin, for which ASKAP gives detailed maps. Typically there are only one or two objects so large in each ASKAP field. In 2021 POSSUM will carry out “Phase II pilot” observations of about 10 fields, which should yield 10 to 15 objects to analyse for the project. Routine data analysis is done automatically for the whole survey, so you will start with calibrated images.  Your job is  

(i)                  to find a well-defined group of targets to analyse, by inspecting the images: these objects are so big that they don’t show up in automatic catalogues: they tend to be registered as several different sources and are most easily recognised by eye. The images are BIG, so this will take a week or two, plus probably a week or so of training.

(ii)                Do some literature research on each object: most of them will be known AGNs, with basic data catalogued such as magnitude of the galaxy and in many cases a redshift and therefore distance. Typically there is not much known about the radio source itself, although there are some exceptions which have been the subject of earlier studies.

(iii)               For each target, extract a cut-out from the data “cube” of maps at 288 different frequencies, including the target and some empty sky surrounding it to analyse the noise properties, and run the POSSUM RMTools code to make a Faraday analysis  of the cutout. This yields maps showing the Faraday Rotation Measure (RM) in each pixel, along with estimates of the intrinsic polarization direction, fractional polarization, and information about the spread of RM within the pixel (“Faraday dispersion”).

(iv)               The hard bit is then to try to make sense of the results. You will look for patterns, e.g. marked asymmetry between the RMs of the two lobes (Laing-Garrington effect), which is likely due to the lobe on the far side of the galaxy having more gas in front of it, and there are also claims of systematic ripples in RM across each lobe, although these are not always seen.  We can do some pencil-and-paper theoretical analysis to assess proposed explanations, such as the numerical simulations by Hardcastle and Krause (https://arxiv.org/abs/1406.5300). The overall aim is to learn more about the magnetic fields in the intergalactic gas and how that interacts with the jets from the AGN.

The L-Band All Sky Survey (L-BASS) MSc project

Supervisor: Dr Patrick Leahy

Co-supervisors: Profs Ian Browne and Peter Wilkinson

After many decades of radio astronomy activity are there any exciting discoveries to be made? Perhaps!  An American experiment, ARCADE-2, consisting of carefully calibrated antennas flown on a balloon to get above most of the Earth’s atmosphere, claims that there is an unexplained radio background emission which only becomes visible at low radio frequencies (See Singal et al.,  2018PASP..130c6001S  for a summary of a conference on the current status).

L-BASS is a Manchester project designed to test whether or not this claim of an unexplained background emission is really true. L-BASS will produce a very accurately calibrated map of the sky at a frequency around 1.4 GHz (in the L-Band) and as well as confronting the ARCADE-2 controversy our map will have impact on the astrophysics of the Milky Way.

The mapping will be done using two 3m-long horn antennas at Jodrell Bank.  The whole receiving system will be deployed in June 2021; by September 2021 we will be collecting science data. The first part of the project will involve contributing to the observing, data collection and particularly the quality control of the time-stream data.

The second part of the project will involve applying corrections for temperature effects and then converting the data into a map of the relative brightness of the northern sky.  In parallel work the L-BASS team will be developing an absolute calibration system based on a cryogenically-cooled reference resistor. By the end of the project we expect to be able to apply the absolute calibration to the map of the sky.

The project will offer training in the fundamental techniques of radio astronomy and sophisticated map-making techniques.

The mysterious nature of turbulence in the interstellar medium

Supervisor: Rowan Smith

The gas of all galaxies is intrinsically turbulent in nature, which has profound implications for how they convert gas into stars. While idealised turbulence is well understood, how well it compares to real turbulent motions in the interstellar medium (ISM) is unknown.

In this project we will use innovative simulations of gas in galaxies like our own Milky Way to investigate how well the turbulence can be described by standard indicators such as the Mach number. We will then investigate how such simulations would appear in emission using synthetic emission to predict the best diagnostics for observers to use to understand the nature of turbulence in real observations of the ISM.

SPEARNET - Exoplanet characterisation through atmospheric transmission spectroscopy

Supervisor: Eamonn Kerins

Projects are available to work within the Spectroscopy and Photometry of Exoplanet Atmospheres Research Network (SPEARNET). SPEARNET is a new Manchester-led international survey, involving colleagues at Manchester, Open University, NARIT (Thailand) and ARIES (India). We are using a globally-distributed network of optical and IR telescopes, from 0.5m to 8m aperture, to undertake multi-epoch, multi-wavelength observations of exoplanet transits.

The multi-wavelength observations are used to measure the transmission spectrum of the atmospheres of Hot Jupiters and Neptunes. SPEARNET has developed an innovative automated selection scheme to choose our targets, a world-leading transit fitting code to analyse the data and construct transmission spectra, and novel machine-learning techniques to speed up retrieval of spectral models.

The goal of SPEARNET is to provide a testbed for how to conduct optimal, objectively-selected statistical studies of exoplanet atmospheres in an era where, thanks to missions such as NASA TESS, ESA PLATO and ESA ARIEL, we expect to have far more targets than we are able to follow up from the ground. Projects are available to work on analysing data as we gather it. You’ll be using and writing software in Python, so experience of, and enjoyment of, using Python is an advantage.