Academic projects search

This project is to develop models of resolved star formation on galactic scales. This will involve modelling a full galactic potential and how it drives the formation of molecular clouds and the onset of gravitational collapse and star formation. feedback from ionisation and supernova will be included to assess molecular cloud lifetimes and star formation efficiencies.

Extensive layers of diffuse ionized gas are observed in the Milky Way and other galaxies. This project will study the structure, ionization, heating, and dynamics of diffuse ionized gas using our newly developed radiation hydrodynamics codes that incorporate feedback processes including photoionisation, stellar outflows, and supernovae. Output from our 3D rad-hydro simulations will be compared with emission line observations of the diffuse ionised gas.

This project will use (and futher develop) our new radiation hydrodynamics codes to syudy the effects of stellar feedback on the structure, dynamics, and star formation rates in star forming regions (parsec sizescales) and the interstellar medium (kiloparsec sizescales). Feedback processes that are readily incorporated into our codes include photoionisation, radiation pressure, dust heating, stellar outflows, and supernovae. In addition to studying these processes in star forming regions, the new numerical codes are also applicble to numerical studies of galactic outflows and the impact of feedback processes and leakage of ionising radiation into the intergalactic medium.

Many gravitational microlensing events involve binary (or multiple) systems, which can be any combination of stars, stellar remnants, brown dwarfs, and planets. Yet, there is quite a lack of systematic studies on what microlensing observations can tell us about the demographics of such systems. This now becomes an even more promising topic as not only photometric but also astrometric microlensing signatures are observed.

This project can take different directions in line with the main interests of the student, where specific questions could include a) the overlapping mass regime between planets and brown dwarfs, b) close binaries, or c) the yet unresolved question why so few binary-source events have been identified (with potential implications on the derivation of planet population statistics).

Most stars form in clusters, where energetic feedback from massive (proto)stars – including outflows, ionization, heating, and winds – shapes the environment and impacts accretion. The relative importance of different feedback processes is a key outstanding issue in our understanding of massive star formation.

The aim of this project is to conduct a large-scale observational study of the role and physics of feedback in young massive (proto)clusters, using ALMA and Jansky Very Large Array (VLA) observations of "Extended Green Objects (EGOs)". The PhD project will focus on imaging and analyzing ALMA observations of the EGO-10, a sample of typical young, massive star-forming regions that exist in a specific evolutionary state where active outflows dominate their infrared appearance.

Determining the demographics of cool planets by means of microlensing is one of the key science goals of NASA's Nancy Grace Roman Space Telescope mission. Already the much smaller data rate of the most advanced ground-based surveys poses a key challenge for the modelling of the detected gravitational microlensing events. The major bottleneck to be overcome is the reliance on human judgement in the data analysis process. Any scalable solution not only needs to be fully-automated ("data-in-model-out"), but also needs to take into account the specific statistics of time-series observations, with their correlated noise and non-Gaussian distribution of measurements. This results in a complex Bayesian interference problem involving an intricate high-dimensional parameter space.

Two fundamental unanswered questions in star formation are: (1) how, precisely, do high-mass stars (M>8 M_sun) acquire their mass? and (2) what produces the very high multiplicity fraction of high-mass (O and B type) main-sequence stars?  Some recent models suggest that the answers to both questions may be linked to the structure and (in)stability of accretion discs around high-mass protostars, which are less well-understood than their low-mass counterparts. This PhD project will focus on the imaging and analysis of high-resolution ALMA observations of a small sample of discs around high-mass protostars, to study disc structure and stability, search for signatures predicted by models of "bursty" or episodic accretion and constrain the level of multiplicity present in the early stages of high-mass star formation.

Exoplanetary atmospheres are far more diverse than those of the planets in our Solar System. The spectroscopic capabilities of the NASA/ESA/CSA James Webb Space Telescope (JWST) are now rewriting our understanding of exoplanet atmospheres, opening new frontiers in atmospheric chemistry, planet formation, and surface processes. This unparalled advancement in the quality of exoplanet atmosphere datasets necessitates similar advances the theoretical techniques and models used to characterise the atmospheres of these distant worlds.

This PhD project will develop and apply new computational modelling techniques to interpret properties of exoplanet atmospheres derived from JWST spectra. The planets of focus will span a broad range of masses and temperatures, ranging from hot giant planets to habitable zone sub-Neptunes.

This project would be eligible for funding including: St Leonard's College Scholarship.

• The Centre for Exoplanet Science

The circumgalactic medium (CGM) that surrounds galaxies provides the fuel for them to grow, and the sink for them to stop growing. Quantifying and understanding the CGM is crucial for linking galaxy growth over cosmic time to the large web-like structures (Cosmic Web) in which they live, and thereby understanding how and why some galaxies continue to grow while others stop forming stars.  Cross-correlation between absorption systems detected in the spectra of background quasars with a foreground galaxy population have revealed important details about the CGM of galaxies. In this project, we will apply this method to unprecedentedly large samples of galaxies and background QSOs from the DESI survey (https://www.desi.lbl.gov). We will study the gas profiles around galaxies with different star formation histories, living in different environments, and in the filaments that feed them. This work will be supported by parallel analyses in simulations.

While high-mass stars (M>8 M_sun) are known to form in stellar clusters and associations, the physics of how (and even whether) the formation of a high-mass star is intrinsically linked to the formation of a surrounding cluster remain unclear. A key limitation has been that testing cluster formation models requires being able to directly compare predicted and observed structures over the extent of a cluster-forming cloud. To address this, this project will bring together the expertise of Dr Claudia Cyganowski in ALMA observations of high-mass star-forming regions and the expertise of Dr Rowan Smith in high-resolution star formation simulations to compare new deep, large-scale ALMA mosaics of a forming stellar protocluster with synthetic observations of custom simulations. The PhD project will include imaging and analysis of ALMA data, multiwavelength analysis including existing VLA datasets, and analysis of and comparison with simulations, with the balance of these elements depending on the interests of the student.