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Ph.D. Projects at the Institute for Astronomy, University of Edinburgh, and the UK Astronomy Technology Centre

Ph.D. projects available for student entry in September 2017 are listed below. See the relevant staff and research overviews for background detail. We also offer Ph.D.s in astronomical instrumentation, primarily supervised by staff of the UK Astronomy Technology Centre.

The new Higg's Centre for Innovation is also currently under construction at the Royal Observatory Edinburgh (ROE), and will be completed in late 2017. This new facility enables us to provide interested PhD students with the opportunity to apply for a six month placement (or two three-month placements) during the second or third year of the PhD, at a range of start-up companies to be based at the centre.  Depending on the company in question, you would have the chance to learn skills in data science, space technology, and other high-tech areas which will be of benefit whether or not you decide to stay in academia.

The IfA and UKATC expect to take on approximately eight new students. The Science and Technology Facilities Council provides full funding for UK nationals or those who meet residency requirements. Scottish Universities Physics Alliance Prize studentships are unrestricted by nationality.

Please note that astronomy projects are also offered by Max Ruffert of the School of Mathematics and Arjun Berera in the Particle Physics Theory group.  We also offer some joint PhD projects with the School of Geosciences on characterising exoplanet atmospheres.

Potential Ph.D. applicants are advised to check back here from time-to-time.

Applicants who would like more information about the specific projects, should contact the named supervisors directly. For more general enquiries, contact Ken Rice.

Important dates and Applications

  • Deadline for applications: Tuesday 31 January 2017. We may consider candidates after this date but do not guarantee to do so. To apply,  follow the instructions for University of Edinburgh Postgraduate Study.
  • Deadline for PCDS applications: Wednesday 1 February 2017
  • Deadline for SUPA applications: Tuesday 31 January 2017.
  • Deadling for Edinburgh Global Research Scholarships (EGRS): Wednesday 1 February 2017 (Overseas students must apply for this in addition to the PCDS and/or SUPA Scholarships)
  • Interviews: We will interview during February and March.
  • Decisions: we expect to finalise our recruitment by the end of March.

Projects for 2017 entry (ordered roughly by astronomical scale from planets to the Universe)

Debris discs around nearby stars

Supervisors: Wayne Holland and Ken Rice

Debris discs are the fallout of comet collisions and their presence around nearby stars is strong evidence that planets also exist in these systems. They provide a unique way to study how planetary systems form and evolve from their primordial structures. Observations tell us about the scale of regions with planetesimals, locations of perturbing planets, and the evolution of the comet population that can affect terrestrial planet habitability. Major scientific goals over the next few years range from searching for analogues of our Kuiper Belt to assess whether the Solar System configuration is unique, providing higher resolution images of the disk structures to better constrain the positions of perturbing planets, and to study the physical and chemical properties of the disc material.

The SCUBA-2 Observations of Nearby Stars survey (SONS) has been searching for debris signatures at wavelengths close to 1mm using the James Clerk Maxwell telescope. It has been targeting more than 100 stars over a range of spectral types, producing spectacular images of disc structures. Once completed in Feb 2015 (although it could be extended in terms of number of targets...), the survey will produce a comprehensive database on discs, a target list for future missions and address key scientific questions on the place of discs in the picture of an evolving planetary system. This student project will focus on the interpretation and exploitation of the SONS results and the planning for further observations, particularly at high (sub-arcsecond) angular resolution using, for example, the Atacama Large Millimetre Array (ALMA).

Habitability of Martian Environments

Supervisor: Charles Cockell

Current theories suggest that habitable environments may have existed on the surface and in the subsurface of Mars over short [1], long [2], or more punctuated [3] timescales throughout its history. Punctuated habitable conditions could have existed in hydrothermal impact systems, outflow channels, and recent data suggest the existence of seasonal flows of briny water on the surface that persist to the present day [4]. This project aims to investigate the habitability of such sporadic environments throughout Mars’ history, using a combination of microbiological and planetary simulation techniques. It will make full use of cutting edge facilities available at the University of Edinburgh, including the Planetary Environmental Liquid Simulator (PELS) [5] and will build on extensive work already completed as part of an STFC consortium grant. Results from the project will have direct applications to the development of instruments for future Mars missions. The candidate should have a degree in biology, chemistry, physics, geology, planetary science, or related disciplines and should be prepared to work in a highly cross-disciplinary fashion.

1 2 3 4 5

Understanding Star Forming Disk Winds

Supervisors: Pamela Klaassen and Ken Rice

Star formation begins with the collapse of a cold core of (molecular) material under its own gravity. The inherent angular momentum in this core is what causes a rotating protostellar disk to form, and it is through that disk that material is able to accrete onto the protostar. But, that initial angular momentum, unless released somehow, can also act to halt accretion as gas velocities increase with decreasing radius. One method for releasing that angular momentum was postulated in the 1980s in the form of a magnetically collimated wind being lifted off of the disk surface. It was only recently that the first evidence for such a molecular wind was first detected, thanks to the unprecedented sensitivity of the ALMA telescope.

This project involves understanding these winds, and involves three components: Quantifying the properties of the first disk wind ever detected (from HD 163296) using proprietary ALMA data, searching through the ALMA archive for evidence for such winds from other protostellar disks, and comparing all of these results to the predicted properties of winds from theoretical simulations.

Using new data from the ALMA telescope, we will first determine some key quantities of this newly observed type of wind: How much angular momentum are these winds able to release from the disk? How much mass is in the wind? How much energy? What indeed, is launching and collimating the wind? The ALMA archive will also prove a rich resource in detecting these types of winds coming from other star forming disks. With a database of disk wind properties, we can then compare these results to those coming from simulations of disk winds to understand what is being properly captured in the simulations, and potentially unlock the wind launching mechanisms and locations.

Building a Sensitivity Calculator for the SKA

Supervisors: Alan Bridger, Pamela Klaassen, Philip Best

The Square Kilometre Array (SKA) is the next big thing for radio astronomy. One telescope, comprised of two arrays (one in South Africa, one in Australia), its goal is to study everything from the epoch of re-ionisation, to the cm sized dust grains in protoplanetary disks, to SETI.

The goal of this project is to generate a sensitivity calculator for the two SKA telescopes: SKA1-LOW and SKA1-MID. The two telescope designs are quite different, and different types of atmospheric and receiver components need to be taken into consideration when creating the calculator. This project is primarily based around developing astronomy software, and, given the opportunity, could involve interaction with business incubation companies at the Higgs Centre for Innovation. There will be a scientific component based on exploiting current radio telescopes (e.g. JVLA, ALMA) to study the emission from nearby high-mass star-forming regions, and then, using the developed sensitivity calculator, quantifying how similar features could be observed with the SKA in nearby galaxies.

PDRs with ALMA and MIRI

Supervisors: Pamela Klaassen

Photodissociation Regions (or PDRs) are the interface between the hot, ionised gas surrounding a massive star and its cooler, molecular surroundings.  The shock physics and chemistry in these PDRs are so dynamic that it’s hard to figure out where to start understanding them.  PDR models are still quite primitive because we haven’t had access to high resolution observations  (spatial *and* spectral) at the relevant wavelength ranges (IR to sub-mm) where the interesting shock chemistry happens (which traces the physics).

In this project, the student will apply for and lead an ALMA project to quantify the PDR and molecular gas in the Horsehead nebula. This region has been chosen because  the ALMA project can act as a pathfinder for a JWST/MIRI Guaranteed time project which (timescales permitting) the student will be able to participate in (JWST data not expected until mid 2019 at the *earliest*).

Wide binaries in Gaia: relevance for star formation and Cosmology

Supervisors: Nigel Hambly and Jorge Penarrubia

The ESA Cornerstone mission Gaia is set to revolutionise astrophysics by mapping the full  six-dimensional phase-space of our Galaxy. The first data release (September 2016) combined with the Tycho2 catalogue provides 3D locations and 2D velocities for more than one million stars in vicinity of the Sun. Subsequent data releases (early 2018 onwards) will provide 100x more stars with full 6D kinematics. The unprecedented quality of the data will provide new insights into many fundamental questions in astrophysics and cosmology. Two suggested areas of application are: (i) the white dwarf initial-final mass relation and it's impact on determination of star formation histories (from the fossil record of the WD luminosity function) and (ii) the existence of a large population of low-mass dark matter substructures devoid of stars. There undoubtedly will be other avenues of research.

In this project the student will learn how to (i) detect stellar clusters and associations by applying Bayesian techniques to 6D phase-space information, (ii) measure the masses and ages of individual white dwarf stars in the clusters and associations, (iii) infer the number of binary stars and measure their separation distribution, and (iv) determine whether the observed binary population has been affected by encounters with dark matter substructures.

The first goal of the project is to construct a Bayesian algorithm to detect candidate wide binary systems exhibiting common proper motion using the Gaia-Tycho2 catalogue and determine which of those can be kinematically associated with clusters and moving groups with well defined ages. The second task is to model the evolution of wide binaries in a Milky Way potential with and without dark matter substructures in order to determine their disruption rate and model the observed separation distribution of the surviving systems. This project has potential significant impact in areas of astrophysics such as star formation histories, chemical enrichment models, the birth rates of supernovae and the nature of dark matter.

Automated classification of variable stars in large synoptic surveys

Supervisors: Nicholas Cross, Annette Ferguson and Bob Mann

Astronomy has entered a new era of wide field time variability surveys, with ambitious all-sky surveys such as Pan-STARRS ongoing and the LSST being planned. Given the amount of data generated by these surveys, it is essential that data archives can provide robust variability classifications that allow astronomers to pick out useful (i.e. high-completeness, unbiased, low-contamination) subsamples efficiently.

The Wide-Field Astronomy Unit at the Institute for Astronomy is currently archiving data from UKIRT WFCAM and VISTA, the current fastest near-infrared surveys. These will be the largest near-infrared surveys for some time. The VISTA Variable in Via Lactea (VVV) survey, which commenced in 2010, is the first large near-infrared survey of variable stars and will eventually observe of order 1 billion stars over 80 epochs as it covers the Galactic plane and bulge. The main science goal is to find and identify RR-Lyrae and Cepheid stars to estimate accurate distances to structures in the bulge.

This project will look at ways to automatically find and classify variable stars using a range of heterogeneous data. It will focus on the near-infrared data in the WFCAM and VISTA datasets, since these data are archived in Edinburgh and near-infrared classification is less developed than optical classification, but the techniques may be applied to large optical datasets such as PanSTARRS (also available to Edinburgh astronomers) and later on to Gaia.

VISTA: VISTA Science Archive

Measuring the distribution of Dark Matter in the Milky Way and its satellite galaxies

Supervisor: Jorge Peñarrubia 

The nature of Dark Matter (DM) constitutes one the most important question in modern Physics. Although DM seems to be present in all galaxies in the Universe, it is in the Milky Way where we have the most accurate data to infer its microscopic properties. In the next few years a large number of photometric and spectroscopic surveys will measure the distance and radial velocities of millions of stars in the Local Group, providing an unprecedented body of observations to constraint the amount and distribution of DM in and around our Galaxy.

In this project the student will learn how to (i) construct dynamical models of the Milky Way and its satellite galaxies; (ii) perform N-body simulations of stellar tidal streams; and (iii) compare survey data against theoretical models using Bayesian techniques of inference.

The initial task will be to construct a Milky Way galaxy composed of bulge, disc and DM halo based on the data provided by state-of-the-art photometric and kinematic surveys, such as SDSS, Pan-STARRS, Gaia-ESO. Based on these data, special emphasis will be given to the construction of N-body models that simulate the tidal disruption of small systems, such as dwarf galaxies and globular clusters, and to the analysis of the associated tidal streams, as these provide the most accurate tracers of the Milky Way potential known to date. This project will provide key modelling tools to mine Gaia data, which is currently measuring the 3D-position and 3D-velocity vectors of about a billion stars in our Galaxy.

Unravelling the Histories of Satellite Galaxies - Bridging the Gap Between Simulations and Observations

Supervisors: Bryan Gillis and Jorge Peñarrubia

Galaxies which reside in dense environments have been observed to differ in many ways from isolated galaxies. They tend to have more prominent bulges, appear redder, and have less active star formation. Hypotheses have been proposed to explain these observations, involving eg. the stripping of gas from satellite galaxies as their orbits bring them near the centres of their host groups.

Modern N-body dark matter simulations allow us the ability to trace the histories of dark matter haloes which host satellite galaxies. We can thus use these simulations to match the observed positions and velocities of satellite galaxies to their possible orbital histories.

In this project, the student will develop a model for how satellite galaxies are affected by their environment through effects such as ram pressure and tidal stripping. They will then use observations of galaxy groups in wide spectroscopic surveys to test the predictions of this model, comparing the observed phase-space positions of galaxies, their colours, and their morphologies to the model's predictions. This will help us to better understand the impacts of different environmental factors on star formation, particularly with respect to the role of the hot gas reservoirs which surround galaxies. It will also help us better understand the relationship between morphological and colour changes in galaxies, providing a fuller picture of galaxy evolution.

Mapping the chemical abundances of galaxies in the Local Volume with KMOS & the E-ELT

Supervisor: Chris Evans 

A promising new method to probe chemical abundances in external galaxies is to use red supergiants (RSGs), which are young and massive stars that are extremely bright in the near-infrared. From analysis of J-band absorption-line spectroscopy of RSGs we can map the chemical abundances of their host galaxies directly. This project will be as part of an international team working with new observations of RSGs in galaxies at Mpc distances, taking advantage of Guaranteed Time Observations with the KMOS instrument at ESO's VLT. The observations will be analysed with state-of-the-art model atmospheres to obtain stellar metallicities, providing detailed abundance information for each galaxy and, ultimately, new constraints on the important relationship of galaxy mass and metallicity.

This project could also include work relating to future observations of RSGs with the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT). The UKATC has key roles in ELT instruments, including the first-light IR spectrograph (HARMONI) and plans for a multi-object spectrograph (MOSAIC). These will open-up the hugely exciting prospect of direct chemical abundances of individual stars out to distances of tens of Megaparsecs for the first time - a significant volume of the local Universe, containing entire galaxy clusters.

The Faint Stellar Envelopes of Nearby Galaxies

Supervisor: Annette Ferguson

The faint outskirts of galaxies hold many clues to their past histories. These regions are where the tidal debris from past accretion events are most obvious and where the ages and metallicities of stars have great power in discriminating between competing models of galaxy assembly. Galaxy outskirts also contain sizeable populations of faint satellite galaxies and ancient star clusters, many of which possess properties which challenge conventional definitions of these objects. This PhD project will focus on a study of galaxy peripheries beyond the Local Group, and will exploit resolved star data from facilities such as the VLT, Subaru and the Hubble Space Telescope, including a new state-of-the-art survey of the M81 Group with Hyper Suprime-Cam. There will also be opportunities to plan for science exploitation with the upcoming JWST (launch 2018) and Euclid (launch 2020) missions, as well as the LSST (survey operations begin 2022) which will provide an exquisite view of the resolved stellar populations and star clusters in the peripheral regions of a significant sample of nearby galaxies.

 

The Star Formation History of Local Group Disc Galaxies

Supervisor: Annette Ferguson

Disc galaxies contribute significantly across all epochs to the stellar mass density in the Universe, yet the details of their formation and evolution are still greatly debated. Important constraints on the star formation and chemical evolution histories of galactic discs can be obtained from deep colour magnitude diagrams (CMDs) which reach back to the earliest main sequence turnoffs as well as near-IR observations of resolved stars which probe the luminous intermediate age populations. This project will use a combination of such datasets to analyse and interpret the spatially-resolved star formation histories in the discs of the two Local Group galaxies, M31 and M33. Our external vantage point and their relative proximity mean that these two systems offer some of the best opportunities we have to study the detailed evolution of disc galaxies. There will be also opportunities to compare these galaxies to the Milky Way through the use of Gaia data (first fully sky astrometry released late 2017) and to plan for extending these kinds of studies to galaxies beyond the Local Group with the upcoming JWST mission (launch 2018).

Growing Pains: How do the first galaxies grow?

Supervisor: Sadegh Khochfar

Shortly after their birth proto-galaxies go through a growth spurt doubling their mass on very short time scales. During this violent phase of their evolution it is likely that their morphological shape and physical properties continuously change. How this change takes place, what the physical drivers are and how these first galaxies look are open questions in modern astrophysical research. These questions are very timely given the upcoming launch of the James-Webb-Space-Telescope, which will b able to probe any theoretical predictions.

project will aim at using state-of-the-art high-resolution cosmological simulation of the formation of the first galaxies and stars to study the formation and growth of the first galaxies. The simulated data will be used to make predictions and comparisons to available observational data. The student will have access to the simulation data produced by the First Billion Years Simulation, the largest simulation of its kind to date. The student will also have access to a dedicated computing cluster to run additional simulations exploring different physical models.

Formation of the first galaxies and globular clusters

Supervisor: Sadegh Khochfar 

Globular clusters are among the oldest observed gravitationally-bound stellar systems in the Universe. They most likely had their origin during the first star formation episodes in the early Universe. While their masses are comparable to those of the first proto-galaxies, their subsequent evolution is very distinct from them. Proto-galaxies continue accreting gas and forming stars, thereby growing in mass, while globular clusters do not.

This project aims at answering questions including: what is the characteristic difference that causes such different evolutionary paths, and is it possible to predict if an assembly of stars is a proto-galaxy or a globular cluster when observed shortly after its birth? Upcoming observational missions will allow putting the results from this work to the test.

The Ph.D. student will have access to state-of-the-art cosmological simulations, in particular data from the First Billion Years simulation, the largest simulation of the formation of proto-galaxies to date and a large set of local observations of globular cluster in the local universe. The student has access to a dedicated cluster to analyse the simulation outputs and to run additional simulations for the project.

The Baryon Cycle: Simulating the Cosmic Ecosystem of Galaxies

Supervisor: Romeel Davé

The growth of galaxies and black holes is regulated by inflows and outflows of gas, now referred to as the baryon cycle, that connect galaxies to their surrounding cosmic ecosystem.  Hydrodynamical simulations offer insights into such processes within a cosmological structure formation context.  Our group's MUFASA simulations utilises advanced hydrodynamics and feedback modules to provide an unprecendented match to the observed galaxy population, and thus they offer a state of the art platform to investigate baryon cycling.

A student is invited to lead project(s) on characterising the physics and observational signatures of baryon cycling from the MUFASA simulations (and its successors).  A particular focus is studying gas in and around galaxies as a direct probe of the baryon cycle.  This could involve studying hot gas around massive galaxies today, cool inflowing and outflowing gas in star-forming galaxies back to early epochs, and/or exploring the galaxy-gas connection as a unique probe of reionization.  A key aim is to connect the full 6-D dynamical information available in simulations to observations from major facilities such as ALMA, JWST, SKA, Athena, and E-ELT, and develop optimal paths towards observationally constraining the physics of the baryon cycle.  The student will run simulations using our group's allocation on the Archer supercomputer at EPCC, and contribute to our extensive Python toolkits for simulation analysis.

Galaxy Formation and Dark Energy Using the Equilibrium Model

Supervisor: Romeel Davé

Though the physics of galaxy formation is incredibly complex, a heuristic description of galaxy is formation turns out to be remarkably simple.  This is encapsulated in our "equilibrium model", based on a mass balance equation with free parameters that quantify baryon cycling.  Using only 10 free parameters (far fewer than traditional semi-analytic models) constrained via Bayesian MCMC, it fits the observed scaling relations of stellar, metal, and satellite growth within galaxies and halos across much of cosmic time, including the scatter around these relations.

A student is invited take the lead on our group's work in one or more of three areas related to the equilibrium model: (i) Improve constraints on dark energy from upcoming large-area surveys such as DES, LSST, and Euclid by using the robust Bayesian posteriors provided by the equilibrium model; (ii) Understand the physical implications for feedback processes in galaxy formation by comparing equilibrium model baryon cycle constraints with that from hydro simulations; (iii) Extend the equilibrium model to include black holes, neutral gas, and molecular gas.

Using the Spitzer-IRAC Equatorial Survey (SpIES) to disentangle the link between black holes and galaxies

Supervisor: Nic Ross

The link between massive galaxies and the central super-massive black holes (SMBHs) that seem ubiquitous in them is now thought to be vital to the understanding of galaxy formation and evolution. As such, huge observational and theoretical effort has been invested in trying to measure and understand the physics involved in these enigmatic systems. A key observational resource in making progress for both cosmological and black hole physics are wide-field quasar surveys, both in the optical and the mid-infrared.

To this end, new deep mid-infrared data from the Spitzer Space Telescope have been acquired, on the SDSS Stripe 82 field, as part of the `Spitzer-IRAC Equatorial Survey' (SpIES) Exploration Science programme (the largest area survey ever conducted by Spitzer). This dataset is ready to be used to discover accreting black holes at the centres of galaxies, i.e. quasars, that are potentially missed in optical surveys, and from there, to make progress on the energy budget that is available to influence the evolution of the host galaxies. A longer term part of this project will involve ramping up for the launch of the James Webb Space Telescope in late 2018.

The role of AGN in Galaxy Evolution

Supervisor: Philip Best

Essentially all massive galaxies in the nearby Universe contain a supermassive black hole at their centres. In recent years it has become apparent that the energetic feedback from these black holes (during their periods of growth: active galactic nuclei - AGN) can have a profound effect on their host galaxies, terminating star formation and controlling the growth of galaxies. Of particular importance are the radio-loud AGN, which possess powerful jet outflows that can extend hundreds of kpc. Recurrent radio-loud AGN activity is now a well-established feature in the evolution of the most massive galaxies. This project will take advantage of new deep and wide radio survey data from the Low Frequency Array (LOFAR), coupled with an extensive spectroscopic follow-up campaign using the new WEAVE multi-object spectrograph on the William Herschel Telescope. LOFAR is a new radio interferometer in Europe, and a key pathfinder for the Square Kilometer Array at the end of the decade. LOFAR is carrying out wide-area radio surveys to much greater depth than every before, offering a new opportunity for detailed characterisation of AGN activity, and the associated energetics, in the nearby Universe. In parallel, ultra-deep imaging over smaller areas of sky with excellent-quality multi-wavelength data will permit precise measurements of how (and why) this AGN activity evolves across cosmic time. Spectroscopic follow-up of extensive samples of these LOFAR sources is one of the key science drivers of WEAVE and is crucial for maximising the astrophysical understanding from these surveys. This Ph.D. project will bring together this very powerful combination of datasets to greatly advance our understanding of AGN activity and, in turn, the interplay between the growth of supermassive black holes and that of their host galaxies.

Testing theories of galaxy formation using the Intergalactic Medium

Supervisors: Avery Meiksin, Sadegh Khochfar and Eric Tittley

Numerical simulations of the intergalactic medium (IGM) in a cold dark matter (CDM) dominated cosmology with a cosmological constant reproduce the observed properties of the IGM to high precision, a major triumph of the CDM model. This project builds on this success by taking the next step: using IGM simulations as a tool to study models of galaxy formation. Massive galaxies are predicted to produce jets of gas driven by massive black holes formed in their nuclei. The student will use state-of-the-art numerical simulations to investigate the impact of such Active Galactic Nuclei galaxies on the surrounding IGM.

The student will be part of a group performing numerical computations in astrophysics at the Edinburgh Centre for Computational Astrophysics (ECCA). More information on the group is available at: ECCA.

Modelling Reionization of the Intergalactic Medium using GPU technology

Supervisors: Eric Tittley and Avery Meiksin

When the first stars formed in the early universe, their radiation contributed in whole or in part to the heating and ionization of the cool intergalactic gas from which they formed. This star formation occurred concurrently with the assembly of the first proto-galaxies and galaxies in a process where feedback forces were in an abundance. While many of the forms of feedback may never be modelled from basic physics, the feedback caused by the radiation field is within our grasp. Much success has been had in modelling the basic geometry and temperature of the radiation feedback, but computational challenges have prevented modelling the hydrodynamical response.

Following on the work of a previous postgraduate student who developed core tools for fast ray tracing in cosmological hydrodynamical simulations, this project will explore the hydrodynamic feedback during the epoch of reionization. Expertise in modern high-performance computing will be acquired while adding to our picture of how galaxies came to be the way they are.

The end of the dark ages

Supervisor: Avery Meiksin

A paramount goal of modern cosmology is the discovery of the Epoch of Reionisation. At this time, the first galaxies and quasars transformed the Universe from a neutral state to the highly ionized one it is today. The observational signature of the expected signal, however, is still unknown. Its pattern on the sky and in frequency will reveal the nature of the sources, both for ionizing the hydrogen formed in the Big Bang and heating it before it is fully ionized.

The purpose of this project is to use numerical simulations to predict the radio signature the Square Kilometre Array should detect under different model assumptions. An essential part of the calculation is the evolution of the spin temperature, including the physics which its determination involves. The student will be part of a group involved in cosmological structure simulations at the Edinburgh Centre for Computational Astrophysics.

Facing the challenges of next generation weak lensing cosmology

Supervisor: Joe Zuntz

 

Weak lensing is a powerful observational technique for mapping the gravitational fields of the Universe by tracing how they distort the light from distant galaxies.  This project looks at the challenging aspects of lensing for next-generation telescopes like the Large Synoptic Survey Telescope and Euclid, using precursor data from existing telescopes.  The student will focus on a range of lensing projects, with options to work at both the pixel level and on the extraction of cosmological constraints from the final reduced measurements.
On the pixel level, analysing images to measure lensing involves modelling the shapes of the imaged galaxies - fitting simple or not-so-simple profiles to their light in large numbers. Methods for this have often neglected or simplified two possibly important aspects of galaxies.  First, galaxies are really three-dimensional, and our models are usually 2D.  Second, we sometimes assume that galaxies have the same shape in different colour bands, whereas in fact they will vary.  This project will determine the impact of both of these issues in preparation for LSST.  
On the cosmological parameter level, existing and future data will constrain the growth rate of cosmic structure over the past 10 billion years.  This project will look at novel ways of modelling that growth.

The Detectability of Self-Interacting Dark Matter in Cosmological Structure: The View from Numerical Simulations

Supervisor: Eric Tittley

The nature of dark matter is one of the great questions of modern physics. Constraints on candidate particles would be made if it were found that dark matter interacted non-gravitationally, even if weakly. Observations compared to simple models and simulations generally give upper limits but some have claimed a small but non-zero cross section. But the results are strongly dependent on what form the self-interaction takes, a point lost in many of the analyses and reported results.  What is required is an review of the various interaction forms, their suitability for simulation, and simulation with all other aspects held constant.

The student will conduct simulations of self-interacting dark matter as implemented by the various previously-published works, but in a single code for direct comparison. The observations to be compared with are maps of the substructure in galaxy halos

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