Note that other projects targeting exoplanet science are offered by the Atmospheric, Oceanic and Planetary Physics sub-department, and listed on their website.
Small worlds from other stars: discoveries in the survey era of interstellar objects
Supervisors: Chris Lintott, Michele Bannister (University of Canterbury, NZ)
Interstellar objects — small bodies flung free from distant solar systems, detected on their way through ours — provide a unique opportunity to study the process of planetesimal formation across the galaxy, to test our understanding of the Milky Way’s history and dynamics, and may have played a crucial role in forming the planets.
Though only two (1I/‘Oumuamua and 2I/Borisov) have been seen to date, the upcoming Vera Rubin Observatory’s optical LSST survey (first light 2025) and NASA NEOSurveyor infrared space telescope (first light 2027) will provide a rich harvest of such objects. This DPhil provides an opportunity to get involved in all aspects of the study of ISOs, from extending our Ōtautahi-Oxford model (Lintott et al 2022; Hopkins et al. 2023, 24) which predicts their properties, to survey simulation and operation, and observational follow-up with major telescopes including CFHT.
Given that studying ISOs involves understanding the chemical evolution of the Milky Way, planetesimal formation, galactic dynamics and the chemistry and behaviour of small bodies, the project would suit a student with broad interests and a willingness to learn. Travel to New Zealand and to observatories is also a strong possibility.
Characterising activity and searching for exoplanets the Terra Hunting Experiment
Supervisors: Suzanne Aigrain
Description: Current radial velocity instruments reach precisions of 30cm/s or less, which should allow the detection of small, temperate planets orbiting stars like the Sun. The main challenge is to separate the small, sinusoidal signals caused by the planets from the complex, evolving variability of the host stars. The Terra Hunting Experiment (THE) is an ambitious, 10-year RV survey aiming to detect Earth analogues around nearby Sun-like stars. It will use the HARPS3 instrument, which is currently being assembled in Cambridge and will be installed on a fully renovated and robotised 2.5m Isaac Newton Telescope (INT) on La Palma in late 2024. After commissioning and science verification, the survey will begin around March 2025. THE employs a unique strategy of intensive (nightly) monitoring of a few dozen stars over a decade, which will be selected after 1-2 years from an original candidate target list of around 200 stars. While the full, 10 year dataset will be needed to detect Exo-Earths, the first couple of years of data will already enable the exploration of unchartered areas of parameter space, including for example super-Earths on Venus-like orbits. The main focus of the project will be to analyse early THE data to a) improve our understanding of the activity properties of the target stars prior to down-selection, and b) start to constrain the planetary systems orbiting them. In the first year, before THE operations begin, the student will familiarise themselves with the required methods using existing data from similar instruments. In the second or third year, we will also explore the possibility of combining THE with GAIA data (including astrometry to constrain planets on wide orbits, and moderate resolution near-infrared spectroscopy to constrain the activity of the target stars).
Catchy artists impression of Kepler 186 f and THE logo attached for illustration purposes. Credit for the artist’s impression: NASA Ames/SETI Institute/JPL-Caltech
New Windows on Exoplanet Atmospheres
Supervisors: Jayne Birkby
In our search for a second Earth, we have uncovered a wild and diverse range of exoplanets, from the enigmatic sub-Neptunes to molten lava worlds. Exoplanets are some of the most complex astrophysical objects, and their atmospheres are their key observable, requiring 3D and time-dependent modelling. Each new observational window we can open on them, from wavelength to spatial and spectral resolution, brings a wealth of new knowledge. This DPhil project seeks a student eager to explore exoplanet atmospheres in detail through observational and simulated data, with input from theoretical modelling. In particular, the student will develop cutting edge techniques with high resolution spectroscopy that will prepare the Extremely Large Telescopes to soon begin exploring the diversity of rocky worlds, and in even greater detail with the future Habitable Worlds Observatory. This can be addressed through a variety of studies, from the reflected light of hot Neptunes or the compositions of super Jupiters, to mapping young gas giants, or even the search for exomoons. The student will join Prof Birkby’s group working on exoplanet atmospheres at Oxford Astro, and will be encouraged to engage with the broader planetary exoploration community within Oxford, including the Atmospheric, Oceanic and Planetary science department, and the Earth Science department.
Circumbinary discs and planets
Supervisor: Katherine Blundell
In recent years the existence and significance of circumbinary discs, orbiting outside of pairs of binary stars in orbit around one another, has emerged. Not only are these purported to have significant dynamical back-reactions on their inner binary stars (and hence their evolution) and in the development of nova explosions but they are in some cases likely to be the breeding ground of Tatooine-like circumbinary planets. The goal is to explore and understand the nature of binary star systems that host such circumbinary structures, using data from the Global Jet Watch telescopes (PI K Blundell; www.GlobalJetWatch.net).
Galactic explosions and their fallout
Supervisor: Katherine Blundell
Nova explosions occur much more frequently than supernova events and arise as the result of a thermonuclear runaway on the surface of a white dwarf. The recent discovery of jets being ejected at the onset of a nova explosion, which have speeds of a few thousand km/s, suggests an important means by which the inter-stellar medium can be enriched by the products of nucleosynthesis that take place on the surface of the white dwarf. The goal is to investigate the mechanisms by which these processes take place, and the efficacy of enrichment of the ISM by jets from nova explosions, using time-lapse data from the Global Jet Watch (PI K Blundell; www.GlobalJetWatch.net).
The Next Phase of Technosignature Searches: Anomaly Detection in Large Optical Datasets
Supervisors: Andrew Siemion, Steve Croft, Joe Bright
Breakthrough Listen, headquartered in the Department of Physics since 2023, is humanity’s most comprehensive search for technosignatures (indicators of technology as a proxy for extraterrestrial intelligence). The Listen team employs cutting-edge digital hardware at telescopes across the world and in space, developing new algorithms and approaches to ingest and process enormous streams of data.
With instruments such as the Vera C. Rubin Observatory soon starting their surveys of the sky, and pathfinders and precursors to the Square Kilometre Array telescope already producing outstanding science, the time is ripe to harness the tools of modern astronomy to expand technosignature searches into their next phase.
The incoming DPhil student will focus on the search for anomalies in Rubin data. By applying machine learning algorithms, objects can be classified by colour, orbit (for Solar System objects), time variability, and other parameters, and rare classes of objects can be identified and their behaviour modelled. A key tool in selecting and understanding true outliers will be the use of active learning to refine the clustering. The Rubin dataset is expected to contain many examples of known sources such as interstellar objects and stars with anomalous variability characteristics, and potentially entirely new classes of object that can be studied by careful application of ML tools.
In addition to looking for technosignatures as we seek an answer to the profound scientific question, “Are we alone?”, the incoming student will be encouraged to explore synergies with other areas of astrophysics. As demonstrated by the discovery of pulsars by Jocelyn Bell Burnell, unknown wonders are waiting to be found.
The Next Phase of Technosignature Searches: Anomaly Detection in Large Radio Datasets
Supervisors: Andrew Siemion, Steve Croft, Joe Bright
Breakthrough Listen, headquartered in the Department of Physics since 2023, is humanity’s most comprehensive search for technosignatures (indicators of technology as a proxy for extraterrestrial intelligence). The Listen team employs cutting-edge digital hardware at telescopes across the world and in space, developing new algorithms and approaches to ingest and process enormous streams of data.
With instruments such as the Vera C. Rubin Observatory soon starting their surveys of the sky, and pathfinders and precursors to the Square Kilometre Array telescope already producing outstanding science, the time is ripe to harness the tools of modern astronomy to expand technosignature searches into their next phase.
The incoming DPhil student will focus on the search for anomalies in data from the Breakthrough Listen suite of radio telescopes, particularly SKA precursors and (looking forward) the SKA itself. Data from these facilities can be supplemented by data mining a variety of archival datasets.
By applying machine learning algorithms, signals can be classified by their spectral properties, time variability, polarisation, modulation, and other parameters. Clustering will enable rare classes of objects to be identified and their behaviour modelled. A key tool in selecting and understanding true outliers will be the use of active learning to refine the clustering.
In addition to looking for technosignatures as we seek an answer to the profound scientific question, “Are we alone?”, the incoming student will be encouraged to explore synergies with other areas of astrophysics. As demonstrated by the discovery of pulsars by Jocelyn Bell Burnell, unknown wonders are waiting to be found.