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PhD projects at the Institute of Origins.

A list of possible PhD projects at the Institute of Origins appear in the following pages. If you have any questions regarding any projects please contact the individual supervisors. Also if you have other suggestions for a project please contact us as well. The chemical composition of forming regions near and far ...... 3 ! Modelling the solubilities of organic solids in liquids: application to the geology and of ...... 4! Modeling turbulent flows in solar quiescent prominences ...... 5! The zoo of exo-planets...... 8! Understanding the formation of heavy negative at Titan and ...... 9!

Mapping anthropogenic versus natural sources of atmospheric CO2 ...... 11! Probing Large Scale Structure with High Energy Neutrinos...... 13! Future Missions and High Energy Neutrinos ...... 15! Measuring Cosmic Particles and the Upper Atmosphere with LOFAR...... 17! Mimicking planetary environments for assessing the survivability of bacterial within an artificial environmental chamber. A combined planetary atmosphere and microbiological study for exploring ...... 18! Study of a Large Modular Cerenkov Detector : PhD proposal for Origins ...... 20! 's equations, the birth of black holes and gravitational waves...... 22! Do fundamental constants vary in time? ...... 23! Dust and in low-metallicity dwarf ...... 24! Guiding the implementation of new ground and space observatories for...... 25! direct detection...... 25! Chemodynamical modeling of galactic discs...... 26! Comparative solar wind effects on planetary atmospheres...... 27! Mercury: its composition, internal structure and magnetic field ...... 28! The Structure of Planetary Exospheres...... 29! What holds an together?...... 30!

(continued) The dark sector of the – dark energy, dark matter and dark spinors ...... 31! Testing General Relativity using Cosmology...... 32! Modelling fermions by means of Cosserat elasticity ...... 33!

The chemical composition of star forming regions near and far primary supervisor: S. Viti (P&A) www.star.ucl.ac.uk/~sv second supervisor: I. Ferreras (MSSL) www.star.ucl.ac.uk/~ferreras

This project deals with the investigation of the chemical composition of massive star forming regions in low and high redshift galaxies. Massive are essential in defining the structure and of their host galaxies: the injection of large amounts of energy and mass into the plays an important role in the distribution of warm gas and hence in evolution.

The student will couple two existing computer models - a chemical enrichment and galaxy formation model with a star formation chemical model - with the aim of 'constructing' the star formation history of a wide range of galaxies, from starburst to dwarfs, from low to high redshift.

This is an extremely topical subject as the cloud-scale observations of molecular clouds and star-forming sites in external galaxies is one of the major goals of ALMA."

Figure 1: Messier 82 is a nearby starbursting galaxy. This image from the Hubble Space Telescope shows the blue disk (where the stars, dust and most of the gas live) and in red the shredded clouds of gas ejected from the Interstellar Medium by the intense rate o of star formation. (Image courtesy Hubblesite.org). Modelling the solubilities of organic solids in hydrocarbon liquids: application to the geology and astrobiology of Titan.

Principal supervisor: A. Dominic Fortes (UCL Sciences) http://www.homepages.ucl.ac.uk/~ucfbanf/ Secondary supervisor: Ian A. Crawford (Birkbeck College Earth Sciences) http://zuserver2.star.ucl.ac.uk/~iac/

Saturn’s giant icy moon Titan is known to have extensive bodies of liquid + on its surface; these form part of a ‘hydrological’ cycle involving liquid hydrocarbon rainfall, surface run-off in drainage channels, and likely subsurface accumulation in aquifers. Methane is also chemically processed in the stratosphere to form solid and C-N compounds; these snow out and accumulate as surface sediments. As these compounds are known to be very soluble in liquid methane/ethane mixtures, we would expect to observe similar behaviour to that seen in terrestrial aqueous systems, such as chemical erosion, sediment cementation, and the formation of evaporites. Kraken Mare; at several hundred Dissolved solutes are also important for kilometres across, it is one of understanding the possible biological Titan's largest methane seas, potential of Titan, since it has been situated close to the north pole. proposed that solid (which is very Rivers and deltaic structures are soluble in liquid hydrocarbons) may be an evident around parts of the energy source for putative alien organisms. shoreline. Radar image.

The objective of this study is to build a chemical thermodynamic model of liquids at Titan’s surface. The model will be used to understand the likely behaviour of meteoric, fluvial, lacustrine, and marine '' on Titan, their interaction with 'bedrock' and with sediments, investigating the conditions necessary for generation of karst terrain, evaporites, and sedimentary lithification. The model will also be used to investigate the astrobiological potential of different environments on Titan in terms of 'nutrient' availability. On a broader scale, the student will also investigate the overall cycle on Titan, using the model to understand how atmospheric evolution could affect the chemistry of Titan’s seas. The project will provide a basis for incorporating both Cassini-Huygens observations, and play an important role in guiding mission planning for a future return to Titan, perhaps within the framework of the TSSM / TandEM mission proposal. Modeling turbulent flows in solar quiescent prominences

Principle supervisor: Prof. Frank Smith (UCL Maths) http://www.ucl.ac.uk/math/staff/FTS.html Secondary supervisor: Prof. Louise Harra (UCL Space and Climate Physics) http://www.mssl.ucl.ac.uk/~lkh

Prominences are large, cool plasma structures seen above the solar limb. They exist in the midst of the surrounding hot corona. There are many mysteries behind these structures - in particular how does the cool plasma stay suspended against gravitational freefall. The japanese space mission, Hinode, was launched in 2006, and observes these structures in incredible detail (see figure). These beautiful structures show dark episodic upflows that exhibit turbulent flow as well as large-scale transverse oscillations. The purpose of this PhD project is to demonstrate the mechanisms of this flow using an understanding (to be developed) of the main turbulent structures involved. Such structures have been much studied and quantified at UCL for magnetic-free fluid dynamics in channels and pipes where solutions known as puffs and slugs are dominant and in external layers where spots and spikes dominate. The project is to use parameter extension techniques to include the required magnetic and thermal effects in full. Nonlinear behaviour and inviscid fluid physics are expected to play major roles. Physical modelling to bring out the main phenomena is to be combined with analysis and computation on reduced systems of differential equations as required. Ideally there would probably be equal weighting to the physical and mathematical aspects of the project.

Figure 2: Prominence on the limb as observed by the Hinode in the Ca II line. Target Properties and Site Selection in Support of the MoonLITE Penetrator Mission

First supervisor: Dr I.A. Crawford (UCL/Birkbeck Research School of Earth Sciences

Co-supervisors: Prof Jan-Peter Muller (MSSL), Dr Adrian Jones (UCL/Birkbeck School of Earth Sciences)

The proposed UK-led MoonLITE mission will advance our understanding of the origin and evolution of the Earth-Moon system by conducting a number of geophysical and geochemical measurements at the lunar surface (see http://zuserver2.star.ucl.ac.uk/~iac/AG_MoonLITE_article.pdf for background). Some of these investigations (e.g. the attempt to detect and characterise organics within the regolith or lunar polar volatiles) have an astrobiological dimension. In order to achieve these objectives it is clearly essential that the penetrators survive their impact with the lunar surface, and preparatory work on defining impact site selection criteria and assessments of whether these can be achieved using existing and planned remote sensing mapping resources will be required. This will be the focus of the proposed project, which will consist of the following elements:

• A detailed analysis of existing () and forthcoming (Kaguya, Chandrayaan-1, Lunar Reconnaissance Orbiter) high-resolution images and derived Digital Terrain Models of potential impact sites so as to develop site selection criteria which minimise the probability of striking rocks on the surface, and to quantify these probabilities at different locations given the landing ellipse likely from MoonLITE. • Perform a similar analysis with regard to surface slopes, so as to minimise the probability of impacting a slope steeper than the requirement set for penetrator survivability. • Identify, regions within permanently shadowed polar craters, that are most likely to harbour polar ice deposits, based in part on existing data (SMART-AMIE) and data that will shortly become available (e.g. Kaguya from 11/09) or that will become available over the next 6-12 months (Chandrayaan-1, LRO). • Determine the mechanical properties of very cold (~90 K) polar regoliths (with and without an icy component) to ensure penetrator survivability in such regions. This aspect of the project may involve computer modelling of penetrator-regolith interactions using the AUTODYN hydrodynamics code. • If time permits, extend the development of penetrator impact site selection criteria to other objects (e.g., Mercury, , Enceladus) that may also one day become targets for penetrator- emplaced scientific instruments.

This research project will benefit from the interdisciplinary interaction of lunar expertise and impact modelling experience in the Research School of Earth Sciences and the planetary 3D mapping expertise and engineering knowledge of penetrator design at MSSL. While performed within the context of MoonLITE, the project will also yield results of value for other proposed lunar surface missions, and also inform future decisions on the feasibility of penetrator missions to other solar system destinations. The student will acquire a detailed understanding of lunar geological processes, impact physics, and the interpretation of planetary images and digital terrain models that will form an excellent foundation for a research career in lunar or The zoo of exo-planets

Prof. Ofer Lahav (http://zuserver2.star.ucl.ac.uk/~lahav/) and Dr. Giovanna Tinetti (http://www.ucl.ac.uk/star/personnel/people/tinetti.htm)

Over 300 planets around stars outside the solar system have been discovered since 1995 (see http://exoplanet.eu for the latest catalogue). This is a new exciting field of research, where new discoveries are made frequently, including by PhD students. Once an exo- is discovered, it is important to characterise its orbital and physical properties, e.g. its period, eccentricity, and chemical composition.

The PhD project will utilize ExoFit, a publicly available software package for the retrieval of orbital parameters of extrasolar planet, developed recently at UCL (Balan & Lahav 2008, , arXiv:0805.3532). The method estimates the orbital parameters from radial velocity data in a Bayesian framework by utilising Markov Chain Monte Carlo (MCMC) simulations. At present ExoFit can derive parameters for either one or two planets. One goal of the PhD project it to extend it for solving a multi-planet problem, and for analysing transit and micro-lensing data. The second aim is to produce with ExoFit a revised catalogue of all known exo-planets (as well as those to be discovered during the course of the PhD!), where the properties will be derived on equal footing, and provide statistics for constraining models for planet formation.

Understanding the formation of heavy negative ions at Titan and Enceladus

Supervisors: Prof. Andrew Coates (Space & Climate Physics, UCL) & Prof. Stephen Price (Chemistry, UCL)

One of the unexpected results from the Cassini mission to was the discovery of heavy (up to 10,000 amu/q) negative ions in Titan’s at 950-1200km altitude (Coates et al, 2007, Waite et al, 2007, Coates 2008). Negative ions were expected lower in the atmosphere (<100km) but not high in the ionosphere where all existing models only involve positive ions. Data from on board experiments (the Cassini Plasma Spectrometer (CAPS) Electron Spectrometer (ELS) and Beam Spectrometer (IBS), and also the Ion and Neutral Mass Spectrometer (INMS), show a remarkable and poorly understood abundance of heavy positive (e.g. Waite et al, 2007) and negative hydrocarbon and ions, providing a rich chemical environment which may emulate conditions at the . The negative ions appear in relatively well defined mass groups at low mass (<100 amu) and in broader groups at higher masses. Chemists with an interest in the ionosphere are already at work to explain the low mass species (e.g. Vuitton et al, submitted, 2008), but the unexplained higher, broader mass groups are of significant interest: they may be related to aerosol and formation (Sagan and Khare, 1979), and ultimately they may affect Titan’s surface, perhaps providing the organic material in the recently discovered dunes. In addition, the plumes of Enceladus, which emanate from fissures on the surface, contain water cluster ions, as well as other positive and negative ions which are unexplained in detail. In this project we aim to understand the formation of the heavy negative ions at Titan and at Enceladus. This will involve data analysis from Cassini and detailed work on the positive and negative ion chemistry at work in these locations. It is expected that as the ions grow, they will react further, and they may also assimilate multiple charges from the ambient ionosphere. Little is known about the appropriate cross sections for the production and loss of the complex organic, nitrile and water related species which are involved, so there is huge potential for theoretical and experimental work. The PhD project will involve: • Further data analysis from the Cassini mission to provide an understanding of the instrument response, the mass resolution available and the limitations of the data • Experimental investigation of the chemical pathways which may create the larger negative ions. This will initially involve developmental work at UCL Chemistry to add a negative ion capability to the Price Group’s ion spectrometers. • The existing coincidence spectrometers at UCL chemistry will be employed to explore further the positive ion chemistry relevant to Titan, with particular emphasis on the role of multiply charged ions (King and Price 2007, Ricketts at al. 2005) • These experimental initiatives will be supported by investigations employing standard computational chemistry packages (Lambert et al 2006). UCL is extremely well placed to undertake this interdisciplinary project. Prof Andrew Coates and group at MSSL discovered heavy negative ions in data from the UCL-provided ELS, and have access to negative and positive ion data from Titan and Enceladus. Prof Stephen Price and his group are world experts in multiply charged ions and the processes forming them, and are studying ion formation processes in the interstellar medium and in planetary (Price 2007). A joint PhD project between UCL Space & Climate Physics and UCL Chemistry is the ideal way to pursue this potentially high impact project, firmly placing UCL in the lead in this area. This project lies at the interdisciplinary boundary between chemistry and physics and is just the sort of project which Origins was set up to fund. 1. Coates, A.J., F.J. Crary, G.R. Lewis, D.T. Young, J.H. Waite, Jr., E.C.Sittler Jr., Discovery of heavy negative ions in Titan’s ionosphere, Geophys. Res. Lett., 34, L22103, doi:10.1029/2007GL030978., 2007. 2. Coates, A.J., Interaction of Titan’s ionosphere with Saturn’s , Phil Trans Roy Soc A, in press, Oct 2008. 3. Sagan, C. and B. N. Khare, : organic chemistry of interstellar grains and gas, , 277, 5692, 1979. 4. Vuitton, V., P. Lavvas, R.V. Yelle, M. Galand, A. Wellbrock, G.R. Lewis, A.J. Coates and J.-E. Wahlund, Negative ion chemistry in Titan’s upper atmosphere, submitted to Planetary and Space Science, Oct 2008. 5. Waite, J. H., Jr., D. T. Young, T. E. Cravens, A. J. Coates, F. J. Crary, B. Magee and J. Westlake, The Process of Tholin Formation in Titan’s Upper Atmosphere, Science 316, 870 (11 May 2007); DOI: 10.1126/science.1139727. 6. S. J. King and S. D. Price, J.Chem.Phys. 127 134322 (2007). 7. S. D. Price, Int. J. Mass Spectrom. 260, 1 (2007). 8. N. Lambert, N. Kaltsoyannis, S. D. Price, J. Zabka, and Z. Herman, J. Phys. Chem. A 110, 2898 (2006). 9. C. L. Ricketts, S. M. Harper, S. W. P. Hu, and S. D. Price, J.Chem.Phys. 123 (2005). Mapping anthropogenic versus natural sources of atmospheric CO2 Supervisor: A P Jones (Earth Sciences), Co-Supervisor: J-P Muller (MSSL)

The Earth's Carbon cycle is not a closed system, but receives continual geological input from volcano degassing and removal through the subduction of oceanic crust[1]. A new era of remote sensing instruments means that we will soon be able to map and evaluate this natural flux of CO2 in comparison with anthropogenic emissions, which are of immediate concern due to fuel consumption and climate change.

CO2 can certainly be measured from space, and its variation over specific regions has, for example, confirmed seasonal drawdown by vegetation[2]. We are becoming involved in the planning and imminent arrival of the next generation of satellites to monitor CO2, including the NASA Orbiting Carbon Observatory (OCO) which will provide highly precise (column-averaged CO2 dry air mole fraction, better than 1 ppm) quantitative data with a short (~3 week) update cycle capable of correlation with 4x4 km areas on the ground. Distinctive geological features that control volcanic CO2 emission, range from elongate continental rifts to individual oceanic islands, ice-bound volcanoes (no vegetation) and some are complicated by proximity to urbanisation. Ideally detailed ground truth “hot spots” will provide calibrations against the remote data, and we require contrasting volcanic sites to evaluate primary controls on CO2, using multiple techniques. We will use methods developed for SCIAMACHY*data retrieval as a precursor to the new OCO data, to target urban versus natural/volcanic CO2.

The student will benefit from combining the volcanic expertise Jones’ group who have been studying volcanic CO2 in the East African Rift and Italy [3-4], with global mapping expertise at MSSL. The coPI is also heavily involved in technology development for monitoring CO2. Global ArcGIS data sets have already been compiled by Muller using novel light scattering at night to determine CO2 and correlate simultaneously with urbanisation. The student will also help in the planning and installation of remote data collecting stations in key volcanic locations in Europe and the world, in collaboration with regional volcano research groups, where the variable pace of gas emission is also used to monitor hazard potential. Combining these with remote satellite receivers is the obvious next step, and the co-PI is an expert in setting up such ground-based monitoring systems.

References

[1] Hards V, Volcanic contributions to the global carbon cycle, Sustainable and Renewable Energy Publication 10, British Geological Survey, (2005) 26 pp

[2] Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) on Envisat [3] Church and Jones, 1995 A.A. Church and A.P. Jones, Silicate-carbonate immiscibility at Oldoinyo Lengai, Journal of Petrology 36 (1995) 869–889

[4] Genge, MJ, Balme, M, Jones, AP, Salt-bearing fumarole deposits in the summit crater of Oldoinyo Lengai, Northern Tanzania: interactions between natrocarbonatite lava and meteoric water, J Volcanol Geothermal Research 106 (2001) 111 - 122

Probing Large Scale Structure with High Energy Neutrinos

Dr. Amy L. Connolly (High Energy Group, Department of Physics and ) and Prof. Ofer Lahav (Astrophysics Group, Department of Physics and Astronomy)

The origin of the highest energy particles in the universe is unknown. The ultra- high energy cosmic rays above 1019.5 eV may originate from within galaxies at distances out to approximately 100 Mpc, and through their directional information may be able to point us to their astrophysical sources. The Auger experiment has measured dozens of cosmic rays in this energy regime. Neutrinos, however, can travel cosmological distances unattenuated and thus can probe greater redshifts and thus earlier times in the universe. So far no ultra-high energy neutrinos have been observed, but current experiments are believed to be close to measuring the expected neutrinos generated by interactions with the cosmic microwave background. The aim of this project will be to study the contribution that neutrinos can make in determining whether the highest energy cosmic messengers originate from sources that follow the large scale structure of the universe or whether they are uniform on the sky. The first scenario will be tested by cross-correlating the high energy sources with 3-dimensional galaxy maps reconstructed by UCL astronomers from the 2MASS redshift survey. In the latter scenario, the highest energy cosmic particles could be decay products of heavy particles in exotic models for new physics. The Ph.D. student will study the ability of neutrino experiments to measure the angular distribution of a measured sample of neutrinos.He or she will also study the feasibility of using established techniques used in astronomy for phasing antenna arrays to improve the angular resolution of future neutrino experiments and increase their sensitivity to neutrinos from known sources. The project may also include analysis of data from new experiments as they begin to be deployed and commissioned, such as proposed arrays in Antarctic ice or large volume salt domes. In addition, the Ph.D. work will include estimation of neutrino masses from cosmological probes such as galaxy surveys and the Cosmic Microwave Background, and combining them with terrestrial neutrino experiments such as KATRIN and MINOS. References [1] ANITA Collaboration (S.W. Barwick et al.), “Constraints on cosmic neutrino fluxes from the anita experiment,” Phys. Rev. Lett. 96:171101 (2006), arXiv:astro-ph/0512265 [2] P. Erdogdu, O. Lahav, et al, ”Reconstructed Density and Velocity Fields from the 2MASS Redshift Survey” Mon. Not. Roy. Astron. Soc. 373:45-64 (2006), arXiv:astro-ph/0610005. [3] O. Host, O. Lahav, F.B. Abdalla, K. Eitel, ”Forecasting neutrino masses from combining KATRIN and the CMB: Frequentist and Bayesian analyses” Phys. Rev. D76:113005 (2007), arXiv:0709.1317. [4] T. Kashti, E. Waxman, ”Searching for a Correlation Between Cosmic-Ray Sources Above 1019 eV and Large-Scale Structure”, JCAP 0805:006 (2008), arXiv:0801.4516. [5] AURA Collaboration (H. Landsman et al.), “AURA: Next generation neutrino detector in the South Pole,” Prepared for Workshop on Neutrino Oscillation Physics (NOW 2006), Otranto, Lecce, Italy, 9-16 Sep 2006, Published in Nucl. Phys. Proc. Suppl. 168:268-270 (2007). [6] P. Gorham, D. Saltzberg et al., “Measurements of the suitability of large rock salt formations for detection of high-energy neutrinos,” Nucl. Instrum. Meth. A 490:476-491 (2002). Future Moon Missions and High Energy Neutrinos

Dr. Ryan Nichol (Department of Physics and Astronomy) and Dr. Ian Crawford (UCL/Birkbeck Centre for Planetary Sciences)

Ultra-high energy (UHE) neutrinos (above 1018 eV) can probe the most extreme astrophysical processes at greater distances than any other cosmic messenger particles. The most promising technique for observing neutrinos at these energies is by detecting the radio Cherenkov signature observable from neutrinos interacting in radio clear media. The dusty surface of the moon called the regolith is one such medium that is radio clear to approximately 10 meters depth. The GLUE experiment sought neutrinos interacting in the moon using a ground-based telescope, as will the LOFAR experiment current being deployed [1,2]. Due to the earth-moon distance, the GLUE experiment had a high energy threshold and thus was only sensitive to the most exotic neutrino flux models. Future moon missions could offer new opportunities for lunar neutrino searches. For example, a lunar orbiter could view large regions of the moon surface at once at a much closer distance, for a sensitive neutrino search in a radio quiet environment that is unachievable with earthbased telescopes. Even a lander could be sensitive to UHE neutrinos during any prelanding orbiting of the moon. If an array of antennas could be deployed on a mission, then the directions from which the neutrinos originated could be determined. Several planned moon landers including MoonNEXT, MoonLITE and the International Lunar Network will be equipped to probe the electromagnetic properties of the regolith and the lunar radio environment, providing important information for the interpretation of both ground-based and any lunar-bound neutrino telescopes that use the moon as their target media [3-5]. A dedicated neutrino experiment could be added to one of these missions through the work in this project. The Ph.D. student will use computer simulations to quantify the sensitivity that lunar orbiters and landers would have to UHE cosmic neutrinos, and assess the feasibility of performing angular reconstruction with an antenna array. He or she will also analyse data from past and planned lunar missions to search for UHE neutrino interactions, characterise the regolith properties and measure the radio environment on the moon for designing future experiments and interpreting current neutrino searches. References [1] P. W. Gorham et al., Experimental limit on the cosmic diffuse ultrahigh-energy neutrino flux," Phys. Rev. Lett. 93:041101 (2004). [2] O. Scholten, et al., Radio detection of UHE neutrinos of the moon," arXiv:astro-ph/0701333 , pp. 109-113. [3] D. Koschny, I. Crawford, B. Houdou, S. Kempf, P. Lognonne, A. Pradier, C. Ricci and P.-D. Vaujour, \Science goals of MoonNEXT, and ESA study to put a lander on the Moon," Geophysical Research Abstracts, Vol. 10, EGU2008-A-03423, 2008. [4] I. Crawford and A. Smith, MoonLITE: A UK-led mission to the Moon," Astronomy & Geophysics,49, 3.11-3.14 (June 2008). [5] http://nasascience.nasa.gov/missions/iln Measuring Cosmic Particles and the Upper Atmosphere with LOFAR

Prof. Mark Lancaster (High Energy Physics), Prof. Alan Aylward (Atmospheric Physics)

LOFAR is an international European radio telescope array currently under construction in the Netherlands, Germany, France, Sweden and the UK. It will be the most sensitive radio observatory for the next 5-10 years making measurements with unprecedented resolution and sensitivity in the low frequency region (30-240 MHz). The direction of observation is chosen electronically by phase delays between the antennas which allows observations to be made in several direction simultaneously. LOFAR allows new fundamental studies of the Universe to be made as well as facilitating unique practical investigations of the environment of the Earth. This PhD project will explore new frontiers in both particle physics and by investigating the origins of the highest energy particles in the universe both through their interactions in the atmosphere and with the surface of the moon and by making detailed studies of the ionosphere. LOFAR has sensitivity to interactions between cosmic neutrinos and the moon at energies far larger than the LHC and as such can be used to probe exotic particle physics models beyond the TeV scale. LOFAR can also probe the electron density of the ionosphere with unparalleled spatial and temporal resolution and at low latitudes which have not previously been studied in detail. The ionosphere can be mapped in parallel with solar radio bursts and holes in the ionosphere can be studied which play a significant role in climate change. References Bo Thid_e, \Nonlinear physics of the ionosphere and LOIS/LOFAR," Plasma Phys. Control. Fusion 49 B103 (2007). Gaussiran, T. et al., \LOFAR as an ionospheric probe," Planetary and Space Science, Volume 52, Issue 15, 1375 (2004). Fender, R., \High energy astrophysics with the next generation of radio astronomy facilities," arXiv:0810.0951v1 [astro-ph] (2008). Scholten O. et al., \Detecting UHE Cosmics Neutrinos o_ the Moon an Optimal Radio Window," Astropart.Phys. 26 219-229 (2006). 1

Mimicking planetary environments for assessing the survivability of bacterial organisms within an artificial environmental chamber. A combined planetary atmosphere and microbiological study for exploring panspermia.

Principal PI: Professor John Ward (Structural and Molecular Biology, UCL) Collaborating PI: Professor Jan-Peter Muller (MSSL, UCL)

There is now detailed knowledge of the conditions in the atmosphere and at the surface of several planets and in the solar system. The surface of , the atmosphere and surface of and the atmosphere and surface of Titan have been described in some detail over the last few years. In parallel with this, on Earth the microbial ecology of extreme environments have been continuing at a great pace and almost all habitats on Earth have diverse microbial colonisation. It is now pertinent to ask questions as to whether the extra-terrestrial environments on these other planets and moons could support in the form of . For example, although continues to be taken very seriously for extra-terrestrial spacecraft it is unknown whether terrestrial organisms could survive in the of interplanetary travel and landing on another . An environmental chamber has been developed at MSSL for testing the Panoramic Camera in Martian conditions. This can simulate the pressure and conditions and be run in a hands off automated fashion. With a small addition, other gases could be introduced into the chamber ( is currently employed) to represent the atmospheric conditions. Such a chamber has been proposed for the CIF Origins spend in 2009/2010 and the student would be heavily involved in its commissioning at MSSL and establishment in Prof. Ward’s laboratory. We propose to use this environmental chamber to simulate the atmospheres of Venus; Mars; and Titan and assess the survivability of terrestrial bacteria in the chamber. Long term studies of several months will be used and the chamber inoculated with single or multiple species of known bacteria or with complex mixtures. The analysis of growth within the chamber will use molecular techniques to assess the diversity (when mixtures are inoculated) and numbers of bacterial through time (16s rDNA and QPCR analysis respectively) The gases within the chamber will also be monitored through time to assess changes made by the growth and respiration of the added bacteria. Model land surface or liquid surfaces will also be used within the chambers to mimic the surface or sub- surface of Titan lakes or sub-surface liquid water on Europa. The environmental chamber has been developed at MSSL and will be fitted with monitoring probes for pressure, temperature, gas composition and with a UV laser light source for monitoring fluorescence (Storrie-Lombardi et al 2008). The chamber will be housed in the Structural and Molecular Biology Department, Building, UCL where we have extensive microbial growth and handling facilities and expertise. We have carried out radiation studies on Antarctic bacteria using conditions defined by a radiation model we have developed (Dartnell et al, 2007a and 2007b) based on from Geant4.

Refs: Dartnell L., Desorgher, J. M. Ward, and A. J. Coates,, (2007a) Modelling the surface and subsurface martian radiation environment: implications for astrobiology. Geophys. Res. Lett. 34, L02207.

Dartnell L. J. M. Ward, and A. J. Coates, (2007b) Martian sub-surface radiation field: and geology, Biogeosciences. 4. 545-558

Storrie-Lombardi, Muller et al. (2008) Potential for non-destructive by the Exomars PanCam. Geophysical Research Letters, 35, L12201

Storrie-Lombardi, Muller et al (2008) Epifluorescence surveys of extreme environments using PanCam imaging systems: and the Mars regolith. SPIE Astrobiology conference, San Diego, 10-14 August 2008. Study of a Large Modular Water Cerenkov Detector : PhD proposal for Origins First Supervisor J.Thomas (HEP), Second Supervisor H. Ziaeepour (Space and Climate Physics)

Executive Summary The goal of the PhD would be to provide a full design of modular water Cherenkov detector and provide its sensitivities to the atmospheric neutrino mixing parameters and matter effects. The sensitivity to both nearby and diffuse SN neutrinos would be calculated.

Overview A large water Cherenkov detector can be used for a number of important physics measurements. One can use neutrinos to observe astrophysical bodies as well as measure some fundamental neutrino properties. The idea of a Megaton neutrino detector poses a problem of an appropriate sized underground laboratory, expensive to excavate and difficult to access thereafter. An alternative approach is to devise a potentially inexpensive, modular water detector which could be submersed in the deep sea. This eliminates the need to build a large underground facility, the need for a mechanical structure to hold a Megaton of water and provides an easily calculable and uniform cosmic background from the water overburden.

Physics Potential 1)Mixing parameters: 105 atmospheric neutrino events per year would be observed in a Mt detector which will allow tighter constraints to be placed on the atmospheric neutrino oscillation parameters (such as looking at whether the mixing is truly maximal). Matter effects through the earth can provide sensitivity to the mass hierarchy. A thorough study of such effects in the earth and their effect on the final neutrino spectrum would be carried out. 2) SN: 5x105 charged current and 2.5x103 elastic scattering (ES) events from a SN at 10kpc could be observed. The directionality of ES events enables location of the SN. The energy spectrum and time evolution of the neutrino pulse can distinguish between different models of stellar core collapse and black hole formation. A study of these events in the detector and a calculation of the efficiency would be carried out. 3) Diffuse SN: the measurement of diffuse SN neutrinos can lead to constraints on the star formation date over the lifetime of the universe as well as putting additional constraints on neutrino decay etc. This is at the intersection of particle physics (neutrinos), astrophysics (SN mechanisms) and cosmology (evolution of the SN rate). 4) Dark Energy: In some models, dark energy is interpreted as coming from varying neutrino mass. This should influence the propagation of high energy neutrinos at cosmological distances and also modifies the interaction of the neutrinos in the detector. Such models and their influence on the events in this large detector would be studied.

Detector Simulation A study of the detector modules using Geant-4 to understand the geometrical distribution of Cherenkov light in a cubic unit, and the pattern recognition efficiency of a number of photon detection devices arranged in different orientations inside the cube will be carried out. A study of the efficiency of identifying neutrino events in a modularized detector to optimize the number and size of the modules taking into account cost and construction simplicity will be studied. Using the simulated detector, a study of the efficiencies for identifying given neutrino physics signals and understanding of the overall scope of such a detector, in particular pushing on the low energy capability to understand the full potential of such a design is essential. There are a number of practical tests which can be performed studying the materials and photon detectors in a high pressure water environment which the student could help to carry out given a promising result from the simulations. Einstein's equations, the birth of black holes and gravitational waves

Rodney G. Halburd (primary supervisor) [email protected] Department of Mathematics

Kinwah Wu (secondary supervisor) [email protected] Space and Climate Physics

Einstein's general theory of relativity is the most successful established theory describing the large-scale behaviour of spacetime. The theory predicts the existence of gravitational waves, which could be used as probes into the origins of various kinds of black holes such as the merger of neutron stars to make a stellar mass black hole and the coalescence of black holes in the centres of galaxies to form the supermassive black holes that might power quasars. Interest in this area has grown recently with the ongoing design and construction of new gravitational wave detectors such as LIGO, VIRGO, GEO 600, TAMA 300 and LISA.

Despite the fact that general relativity has been around for almost a century, there are still many fundamental mathematical and physical problems that remain unanswered. Einstein's field equations are a system of coupled partial differential equations. These equations are very complicated from both the theoretical and numerical viewpoints. The equations do not naturally fall into any of the standard classes of PDEs usually studied (elliptic, parabolic, hyperbolic). Furthermore, the manifold on which a solution is defined is determined by the solution itself. This further complicates the physical interpretation of solutions.

There is no guarantee that the Einstein equations correctly model the universe. The accurate detection and interpretation of signals from the births of black holes depends to a large extent on whether we have the correct general relativistic formulation.

This project will be supervised under a collaboration between UCL's Department of Mathematics and Space and Climate Physics. The prospective student would pursue research that is both mathematically rigorous and physically relevant. Alternate formulations of Einstein's equations (and their generalisations) will be considered. This includes formulations that are essentially hyperbolic and in terms of exterior differential systems. Possible numerical and theoretical advantages will be explored. Another central theme will be the prediction of likely gravitational wave forms corresponding to physically realistic events. The construction and physical interpretation of solutions of Einstein's equations (exact, numerical and approximate) will play an important role.

Do fundamental constants vary in time?

1st supervisor: Dr. R. Saakyan (HEP, Physics and Astronomy) 2nd supervisor: Dr. D. Fortes (Earth Sciences)

Double beta decay (DBD) is an extremely rare radioactive process with a life time many orders of magnitude longer than the . The process involves a simultaneous transformation of two neutrons into two protons emitting two electrons and two neutrinos. The neutrinoless version of this process is forbidden by the standard model and is currently an area of very active research. An observation of this process will lead to new physics and will answer the most fundamental questions such as the value of the absolute neutrino mass and whether neutrinos and anti-neutrinos are identical.

The UCL HEP group is one of the leaders in this area and is actively involved in a currently running experiment (NEMO3) and in an R&D programme for a future detector (SuperNEMO). The two-neutrino DBD was first detected in so-called geochemical experiments. These experiments exploit the fact that very old minerals (billions of years!) with suitable DBD isotopes could undergo a large number of these decays thus compensating the extremely rare nature of the process. It was recently noticed that older and younger geological samples lead to different measured life times of the DBD. The trend is that the older the mineral, the longer the life time. One possible reason for this behaviour is extremely intriguing (and of course speculative): it could be due to time variations of the fundamental constant, the constant which is responsible for the strength of the weak interaction (such as beta decay).

The subject of this proposal is to carry out a systematic investigation to confirm or reject this hypothesis. We suggest to carry out a number of measurements with geological samples ranging from 100 million to a few billion years of age and to compare the half-life results with present day direct experiments (e.g. NEMO3). In order to do this the HEP and Earth Sciences groups should work together to identify suitable samples, understand their history and geological evolution, carry out mass spectrometric measurements, compare with direct experiments data, analyse backgrounds and systematic errors and finally to interpret the results. Dust and star formation in low-metallicity dwarf galaxies.

Supervisors: Mat Page (Space and Climate Physics, MSSL) Mike Barlow (P&A)

When the first galaxies formed, the Universe was highly deficient of elements heavier than helium, which are synthesized in stars. At these early times, supernovae from massive stars would have been responsible for enriching the interstellar medium, while the amount of metals and dust in the interstellar medium would have had a major impact on the process of star formation. One way to make progress in understanding this cycle of star formation and enrichment in the first galaxies is to study the star formation and interstellar medium in nearby analogues, the most promising of which are low-metallicity dwarf galaxies. The project will involve studying the dust and gas emission in dwarf galaxies using far-infrared to submillimetre data from the Herschel Space Observatory, due for launch in Spring 2009, and the dust extinction and star formation properties of the same objects using optical to data. Both supervisors are involved in a Herschel Guaranteed Time programme that will obtain extensive observational data for a large sample of dwarf galaxies. The optical-ultraviolet data will come from the Swift Ultraviolet/Optical Telescope and the XMM-Newton Optical Monitor, both of which were built at MSSL/UCL. The XMM-Newton data are already in hand, and the Swift data will be obtained through MSSL's Swift involvement via a fill-in programme. Guiding the implementation of new ground and space observatories for exoplanet direct detection.

Dr. Giovanna Tinetti and Dr. Peter Doel.

The project proposed here is quite timely: the next five years will see the passage between the “old” generation of space telescopes (Spitzer and Hubble) and the new generation (James Webb, 2014; SPICA, 2017; space missions for direct detection). In particular ESA, ESO, NASA and JAXA are now supporting several studies to assess the feasibility of different techniques for exoplanet direct detection and characterisation missions. According to the most recent studies and experiments, the use of a coronagraph ( Finder-Coronagraph; SEE-Coast; SPICA; VLT-SPHERE; ELT-EPICS) or an occulter (Terrestrial Planet Finder Occultor) seems to show several advantages with respect to interferometry (Darwin, Terrestrial Planet Finder Interferometry), at least for this first generation of exoplanet direct detection missions.

The PhD student will be specifically trained to work at the interface between exoplanet theory and instrumentation, maturing a quite unique expertise. The candidate will be expected to assess the feasibility of few planned instrument performances from ground or space. The combination of a set of modelling tools for exoplanet and spectral simulations provided by G. Tinetti and the expertise of P. Doel in the field of astronomical instruments and optical science, will be crucial for this programme. G. Tinetti is co-I of the mission concept New Worlds Observer (or TPF-O) selected for studies by NASA, member of the science team of EPICS instrument to detect and characterize Terrestrial planets with the ESO Extremely Large Telescope, member of the -Exoplanet Roadmap Advisory Team. P. Doel has a long term experience in the development of astronomical instrumentation, especially adaptative optics and stellar coronography, crucial for exoplanet direct detection missions. This programme will help to plan the instruments and techniques for the next generation of ground- and spacebased observatories, by providing recommendations for the required spectral resolution, instrument performances, wavelength range and signal to noise ratio needed/obtainable to detect the bulk atmospheric composition, physical properties, and trace gas abundances for a range of plausible atmospheres and for a number of different parent stars. This is excellent material for publication and training: this project will be a great opportunity for the student to publish peer review articles but also to learn about the new mission concepts at their incept, with the possibility to be involved in a quite substantial way from the beginning. Chemodynamical modeling of galactic discs.

Daisuke Kawata (Space and Climate Physics, MSSL) & Jeremy Yates (P&A)

This project aims to construct the most sophisticated chemodynamical model of galactic discs. Stars form from the interstellar medium (ISM) and there are both chemical and energetic feedback from stars to the ISM due to supernovae as well as mass loss from evolved stars. It is still unknown how the ISM and stars are affecting each other in the galactic disc. This is a very active area of reserch in astrophysics.

The student will add more sophisticated models of the ISM physics, star formation and feedback to the existing particle-based galactic chemodynamics simulation code, GCD+. The new improved code will be tested and calibrated by comparing high-resolution simulations of rotating discs with the latest multi-wavelength observations of the ISM and stars in discs of galaxies with different masses. The new code will be a unique tool to study the evolution of disc galaxies.

Comparative solar wind effects on planetary atmospheres Primary supervisor: Alan Alward (APL, P&A) http://www.phys.ucl.ac.uk/people/staffmember.php?id=515, Secondary Louise Harra (Space and Climate Physics, MSSL) http://www.mssl.ucl.ac.uk/~lkh

Recent studies of the Earth's thermosphere using the CHAMP spacecraft have shown there are temperature and pressure variations at harmonics of the solar rotation period of 27 days. Thus recurrent structures in the solar wind appear to be affecting the neutral atmosphere: the process for this is not currently understood. A database has been constructed of all the solar wind anomalies - CMEs, CIRs and magnetic clouds since the1960s. These data could be compared to atmospheric ground-based and satellite observations over this time to find which of the structures in the solar wind are most 'geo-effective' in terms of producing fluctuations in thermospheric structure.

The effects on the neutral atmosphere must be transferred from solar wind to neutral atmosphere via the Earth's magnetosphere. In this context, consideration of the interaction at other planets would also be possible and informative: Jupiter and Saturn also have , while Venus and Mars have no shielding magnetic field. Thus, clues as to the mechanism by which the energy is transferred at the Earth may come from comparing what happens at these planets.

UCL has instruments on spacecraft at Saturn (Cassini), Venus (Venus Express), Mars (Mars Express), Cluster (magnetospheric) and Hinode (solar), models of the upper atmospheres of these planets, and expertise in solar and magnetospheric physics. This provides a comprehensive suite of tools for studying this phenomenon of space-to-atmosphere energy transfer at different planetary environments within the Solar System.

We propose a joint studentship to study planetary solar wind-thermosphere coupling. The studentship would focus on the following areas in detail, or could be a combination of two of these areas:

Correlation of solar wind and atmospheric observations at the Earth: This component would focus on the characterisation of solar wind structures and fluctuations in terrestrial thermospheric structure which are (nearly) simultaneous with the arrival of solar wind events at the Earth. The dominant spatial / time scales for solar wind structures will be identified, as well as the corresponding dominant period for the thermospheric response.

Correlation of solar wind and atmospheric observations at other planets: Similar to above, except focussing on datasets for any or all of Mars, Venus, Jupiter, Saturn. Jupiter is important here as a point of comparison, as its main aurorae are internally driven by rotation.

Mercury: its composition, internal structure and magnetic field Supervisors: Lidunka Vo!adlo1, Andrew Coates2, Lars Stixrude1 1Department of Earth Sciences, UCL 2Mullard Space Science Laboratory, UCL

The time is right to study Mercury - it is the target of two orbital missions, MESSENGER (currently on flyby, orbiting 2011) and Bepi-Columbo (orbiting 2019) both of which have instruments on board to study its internal structure, composition and magnetic field. The objective of this PhD project is to use theoretical calculations to determine the structure, composition and evolutionary history of Mercury for comparison with available data as and when it arrives. Mercury, with an average density of 5.4 gcm-3, is only slightly less dense than the Earth (5.5 gcm-3); however it is much smaller than the Earth and therefore the material within its interior is not as strongly compressed. For Mercury to have such a high density, its core must be large (>40% by volume, <70% by mass) and iron-rich (~70% Fe, ~30% silicate). Its small size suggests it must have cooled more rapidly than the Earth and therefore will have a distinct chemistry and evolutionary history. The presence of a magnetic field suggests Mercury has a molten region, although fast cooling means that this may be confined to a rather thin shell. As a result of these differences, it is possible that the dynamo that supports the magnetic field of Mercury differs substantially from the terrestrial dynamo.

Understanding Mercury’s interior requires us to construct geophysical models of its internal structure and evolution. In the first instance, this requires knowledge of the physical properties and melting behaviour of candidate compositions under the appropriate conditions of pressure and temperature, which can be obtained from ab initio computer simulations. These results can then be incorporated into planetary thermal evolution models, thereby providing tighter constraints on the internal structure, composition and magnetic field of Mercury.

The Structure of Planetary Exospheres

Primary supervisor: Nick Achilleos (P&A), Secondary supervisor Graziella Branduardi-Raymont (Space and Climate Physics, MSSL).

Hot neutral exospheres of weakly magnetized planets such as Mars and Venus play a central role in the exchange of energy between the atmospheres of those planets and the solar wind. Processes such as dissociative recombination of molecular ions and charge exchange between ionospheric species and solar wind ions lead to the formation of hot 'coronae' of neutral species such as and .

Evidence for charge exchange in particular comes in the form of observed X-ray halos by spacecraft such as XMM and Mars Express. The exopsheric atomic hydrogen is also a strong source of ultraviolet emission, as observed by SPICAM on Mars Express.

This project will investigate the structure and physics operative at the Martian exosphere, and, if time allows, be extended to further modelling concerned with exoplanetary exospheres.

The UCL global model of the Martian atmosphere will provide a 'lower boundary' of ion and neutral composition on both dayside and nightside of the planet. A 'test particle' approach will be used to follow trajectories of groups of escaping neutrals as they leave the atmosphere and interact with an ambient solar wind flow. Observations - now very extensive thanks to recent missions - and simplified gas dynamic models will be used to simulate the solar wind flow and IMF configuration. If time allows, further modelling of the effect of the 'penetrating' IMF at times of high solar activity will be investigated. This effect is thought to be linked to observed bulk ionospheric outflows.

On the observational side, the emission structures in X-ray and UV from the above sources will be characterised and compared to those which result from applying simple radiative transfer formalisms to the exospheric structure models.

If time allows, the tools and models developed will be applied to exploring the possible structure of hot coronae or exospheres at extrasolar planets. This is particularly applicable to these bodies, many of which are slowly rotating, possibly weakly magnetized gas giants which orbit very close to their parent star and thus would be exposed to a strong solar wind flow. What holds an asteroid together?

A PhD proposal for a project supervised by:

Professor Hilary Downes (Birkbeck Earth Sciences), Dr Geraint Jones (MSSL), and Dr Caroline Smith (Natural History Museum).

Most represent time-integrated records of the history of asteroidal bodies. Many meteorites are breccias, i.e. fragmental rocks that are composed of grains of more than one kind of material. Such breccias may represent the surface or near-surface layers of . Break-up (brecciation) and re- lithification processes are good indicators of the dynamic nature of the early Solar System. Some breccias represent the mixing of fragments after total destruction of parent bodies by impact. Other breccias include fragments derived from other planetary or asteroidal bodies, i.e. fragments of ancient meteorites that impacted the surface of the host asteroid relatively gently and did not cause catastrophic destruction.

What is not well known is the nature of the material that holds the pieces of the brecciated meteorites (and presumably therefore the parent asteroids) together. This problem can be investigated using well-known examples of brecciated meteorites available from the Natural History Museum (London) and other meteorite repositories (e.g. Johnson Space Centre, Houston). Suggestions for the intra-grain material include impact melts that travel along grain boundaries, chilling rapidly to a glass that holds the grains together. Investigations of the intra-grain material will require specialized equipment, e.g. Electron Microprobe analysis, Scanning and Transmission Electron Microprobes, in order to determine its mineralogy and chemistry. Such equipment is available within London, including at the NHM. Other techniques such as Focussed Ion Beam, NanoSIMS, may require travel to other parts of the UK and USA.

Asteroid surface materials are thought to be sometimes strongly affected by the solar wind plasma environment in which they reside, e.g. electrostatic charging of surface materials by the impacting plasma and the photoelectric effect may cause the levitation of small grains and their complete removal from the surface in the case of very small bodies. Studies of these effects in the current epoch as well as under possibly very different plasma environments in the can also be investigated as part of this study. The dark sector of the universe – dark energy, dark matter and dark spinors

Christian G. Böhmer (primary supervisor)! Department of Mathematics, University College London, Gower Street, London, WC1E 6BT, UK

Houri Ziaeepour (secondary supervisor)† Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK

In cosmology, the dark energy is an unusual form of energy that has the effect of increasing the expansion rate of the universe. Dark matter, on the other hand is an invisible matter component whose presence can be inferred from its gravitational effects on visible matter. Dark energy and dark matter form the dark sector of the universe. In recent years, many interacting dark energy models have been investigated. In these models, the early universe contains only dark matter, which over time is transferred into dark energy to yield the late time accelerated expansion we currently observe. One particular model that recently has been put forward is based on a Fermionic description of dark matter and dark energy, called dark spinors. There are many similarities between dark spinors and well understood scalar fields in cosmology, and hence they allow a rich phenomenology that can be explored. As the quantum field theoretical description of dark spinors is not yet fully understood, we also anticipate strong interaction also with the High Energy Physics department.

We specifically concentrate on the following intriguing issues:

• Fermionic dark matter and dark energy models, and relations between them; • Relation between dark spinors and interacting dark energy models; • Solutions of the coincidence problem; • Dark spinor as an inflation field (inflaton) and evolution of cosmological perturbations in such models; • Observable evidence for discriminating between different dark matter candidates in the data from present and near future instruments such as Fermi, Plank, LISA, and LHC; • Particle physics phenomenology of dark spinors.

! Electronic address: [email protected] † Electronic address: [email protected]

Testing General Relativity using Cosmology

Sarah Bridle (primary supervisor) Department of Physics and Astronomy

Christian G. Böhmer (secondary supervisor) Department of Mathematics

This project will test Einstein's law of General Relativity, which is at the heart of studies of the origin of the universe and its constituents.

Our Universe appears to be filled with mysterious ingredients: 25 per cent of which is dark matter, perhaps an as!yet undiscovered particle, and 70 per cent seems to be a bizarre fluid, dubbed dark energy, for which there is no satisfactory theory. Solving the dark energy problem is the most pressing question in cosmology today. Many people believe it is likely that dark energy does not exist at all, and instead Einstein"s theory of General Relativity is flawed.

The student will use a combination of the best existing cosmological data to place constraints on the basic observable quantities that test gravity. This will include the Cosmic Microwave Background light from the fireball phase of the universe and cosmic gravitational lensing, in which images of distant galaxies are distorted as they pass through the intervening dark matter distribution. The latest statistical techniques will be used, extending the industry standard CosmoMC code (Lewis & Bridle 2002) which uses Markov Chain Monte Carlo (MCMC) sampling to explore cosmological parameter space.

The simplest prediction of generalised gravity theories is a different speed of gravitational collapse (growth function), for a given global expansion rate for the universe. A simple approximation to the growth function uses a parameter # where # =0.55 for General Relativity, whereas the Dvali, Gabadadze & Porrati (2000) model suggests that gravity is weaker at larger distances due to leakage into extra dimensions, and #=0.69. This parameter gamma will be constrained using the latest data, along with the other cosmological parameters including the amount of dark matter and the curvature of the universe.

The student will then reconstruct the expansion rate of the universe and the growth rate independently. Cosmologists can attempt to fit this using a dark energy model, or the above (#) model, or a new modified gravity model. This will provide clues to the next Einstein, who needs to explain why the majority of the universe seems to be made of an incomprehensible material.

Modelling fermions by means of Cosserat elasticity

Supervisors: Dmitri Vassiliev and Kinwah Wu

The accepted way of describing fermions mathematically is by means of a spinor field. The aim of the pro ject is to develop an alternative mathematical description. The central idea is that we allow every point of the (spacetime) continuum to rotate and assume that rotations of different points are totally independent. These rotations are described mathematically by attaching to each point a coframe (= orthonormal basis) which plays the role of a dynamical variable.

The idea of rotating points may seem exotic, however it has long been accepted in continuum mechanics within the so-called Cosserat theory of elasticity [1]. The Cosserat theory of elasticity has been in existence since 1909 and appears under various names in modern applied mathematics literature such as oriented medium, asymmetric elasticity, micropolar elasticity, micromorphic elasticity, moment elasticity etc. Cosserat elasticity is closely related to the theory of ferromagnetic materials [2] and the theory of liquid crystals [3, 4]. The idea of rotating points also formed the basis of the theory of teleparal lelism (= absolute parallelism) promoted by A.Einstein and $E.Cartan [5, 6]. Teleparallelism is, effectively, a special of Cosserat elasticity: here the assumption is that the continuum experiences no displacements, only rotations. With regards to the latter it is interesting that Cartan acknowledged [7] that he drew inspiration from the monograph [1] of the Cosserat brothers.

The pro ject is predominantly of a mathematical nature and involves the detailed mathematical analysis of field equations and comparison with existing models (Dirac equation). The first supervisor, Vassiliev, is a mathematician, whereas the second supervisor, Wu, is a theoretical astrophysicist with backgrounds in theoretical physics and pure mathematics. Vassiliev will supervise the pro ject on the mathematical side whereas Wu will oversee the pro ject from a physicist"s perspective.

The project is part of the UCL Institute of Origins.

References [1] E.Cosserat and F.Cosserat, Th $eorie des corps d $eformables, Librairie Scientifique A. Hermann et fils, Paris, 1909. Reprinted by Cornell University Library. [2] J.M.Ball, A.Taheri and M.Winter, Calc. Var. Partial Differential Equations 14 (2002) 1–27. [3] C.Liu and F.Lin, Journal of Partial Differential Equations 14 (2001) 289–330. [4] J.M.Ball, Orientability of director fields for liquid crystals, talk at London Analysis and Prob- ability Seminar, 25 October 2007. [5] Elie Cartan and Albert Einstein: Letters on Absolute Paral lelism, Princeton University Press, 1979. [6] A.Unzicker and T.Case, Translation of Einstein"s Attempt of a Unified Field Theory with Teleparal lelism, http://arxiv.org/abs/physics/0503046. [7] $E.Cartan, C.R. Acad. Sci. (Paris) 174 (1922) 593-595.