About Me
I am a postdoctoral researcher in the Astronomy department at the University of Maryland, working on characterising the atmospheres and interiors of extrasolar planets (exoplanets). I completed my PhD at the Institute of Astronomy, University of Cambridge.
See below for a summary of my research and a copy of my CV. If you're interested in any of my research topics, feel free to get in touch at mcnixon[at]umd.edu.
Connecting sub-Neptune atmospheric and interior models
One of my primary research goals is to better connect models of sub-Neptune atmospheres and interiors in order to develop a fuller understanding of their composition and structure. I am interested in using observational constraints on atmospheric composition to better inform internal structure models, as well as modelling how chemical interactions deep within a planet's interior can influence its atmosphere.
I have developed an open-source internal structure model for exoplanets, which can be found on Github. The model is described in Nixon & Madhusudhan (2021), and a recent example of its application to the sub-Neptune GJ 1214 b can be found in Nixon et al. (2024).
Three-dimensional atmospheric retrieval of exoplanets
I am the lead developer of Aura-3D, a three-dimensional atmospheric retrieval code for exoplanet transmission spectra. Aura-3D includes a forward model that enables rapid computation of transmission spectra in 3D geometry for a given atmospheric structure, and can be used for atmospheric retrievals as well as for computing spectra from general circulation models.
For more information on Aura-3D, see Nixon & Madhusudhan (2022), published in the Astrophysical Journal.
Machine learning for atmospheric retrieval
I have developed an atmospheric retrieval code that uses the Random Forest supervised machine learning algorithm, rather than a Bayesian sampling method such as MCMC or Nested Sampling. In certain cases, this can lead to a considerable improvement in run time.
For more details, see Nixon & Madhusudhan (2020), published in Monthly Notices of the Royal Astronomical Society.
Media and Press Releases
Researchers Measure the Light Emitted by a Sub-Neptune Planet’s Atmosphere for the First Time - University of Maryland press release, 2023
How deep is an exoplanet's ocean? - Astrobites, 2021
Machine learning can help decode alien skies, up to a point - Eos, American Geophysical Union, 2020
Potentially habitable exoplanet could broaden the search for life beyond Earth - CNN, 2020
Large exoplanet could have the right conditions for life - University of Cambridge press release, 2020
Curriculum Vitae
CV should appear below. If not, it can be accessed here: https://drive.google.com/file/d/1VViADhhYtNsnjQzhj59G3Nony9oAGjZ7/view?usp=share_link
Matthew Nixon CV (website).pdf