current projects
Transmission spectroscopy of exoplanet atmospheres. The atmospheres of exoplanets that are detected using the transit method can potentially be studied using the method of transmission spectroscopy. Whilst in transit the light from the host star shines through the atmosphere and may be absorbed or scattered at certain wavelengths. Observations of transits over a range of wavelengths enables us to build a transmission spectrum of the exoplanet atmosphere.
Whilst there are now several thousand known exoplanets, only a tiny fraction have so far been successfully studied using transmission spectroscopy. With the launch of TESS in 2018 and PLATO in th next decade, the number of nearby planets sutiable for atmospheric studies will grow exopenetially. The technique currently allows us to study the atmospheres of nearby hot jupiter- and neptune-mass systems orbiting close to their host, but in the future we should start to characterise more Earth-like planets and begin to look for biomarkers - spectral signatures of candidate life forms.
Together with my former PhD student, Dr Supachai Awiphan (NARIT), I lead SPEARNET (Spectroscopy and Photometry of Exoplanetary Atmospheres Research Network). SPEARNET is a systematic transmission spectrosopy survey of the atmospheres of hot massive exoplanets (above neptune mass). We are gathering observations using a world-wide heterogeneous telescope network. Our first study involving the hot neptune GJ3470b, confirmed Rayleigh scattering in its atmosphere and also placed limits on the mass and proximity of neighbouring planets in the system.
(Preprints/papers from this project)
Space-based microlensing detection of cool exoplanets. At Manchester we are world leaders in the development of detailed microlensing simulation models. Together with my former PhD student, Matthew Penny, and a formar Manchester postdoc, Nick Rattenbury, we developed a detailed microlensing exoplanet simulator based upon the Manchester-Besançon Microlensing Simulator (MaBμLs) using the Besançon Galactic Model developed by Annie Robin (Besancon) and collaborators. This is currently the most advanced survey simulator of exoplanet microlensing. It is being used by the ESA Euclid Exoplanet Science Working Group, which I co-lead, to evaluate the potential of the Euclid dark energy mission to undertake a survey of cool exoplanets as an additional science activity to its main cosmology science programme. Euclid is now under construction and is expected to launch around 2020. The Exoplanet Euclid Legacy Survey (ExELS) could provide a census of coool exoplanets with a comparable precision to that made possible by the Kepler transit mission for hot exoplanets. This would allow a much more complete understanding of exoplanetary architectures and potential habitability, and also help us to better understand the process of planet formation. A cool exoplanet microlensuing survey is also one of the main science goals for NASA's WFIRST mission, which could launch within a few years of Euclid. MaBuLs is also being used by the NASA WFIRST Science Definition Team to evaluate the capabilities of different reference designs for that mission.
(Preprints/papers from this project)
Manchester-Besançon Microlensing Simulator (MaBμlS). Together with Annie Robin and Doug Marshall, I constructed the most detailed theoretical simulation to date of the distribution of microlensing events towards the inner Galaxy, where the vast majority of events have been detected. The simulation is based upon the Besançon synthetic model of the Galaxy, and incorporates a full 3D map of interstellar extinction. Synthetic microlensing maps like these will be crucial to exploit fully the large microlensing datasets now becoming available for constraining the 3D structure of the inner Galaxy. We are currently refining this model using the latest version of the Besançon model together with the latest observational maps of microlensing from the MOA and OGLE microlensing survey teams. The project has developed into the Manchester-Besançon Microlensing Simulator (MaBμlS) which is now available as an online resource. Early versions of MaBμlS have already been used as a basis to generate exoplanet microlensing preditions for spaced-based exoplanet microlensing proposals.
(Preprints/papers from this project)
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