Steven G. Murray

Marie Sklodowska-Curie Fellow

Scuola Normale Superiore

Biography

I am a Marie Sklodowska-Curie (MSCA) Fellow at the Scuola Normale Superiore (SNS) in Pisa, Italy. My research interests are in 21cm cosmology, cosmological structure formation, Bayesian statistical analysis, and creating useful open-source software for scientific applications.

Interests

21cm Cosmology
Bayesian methods
Open-source scientific software and practices

Education

PhD in Astrophysics, 2017
University of Western Australia
BSc (Honours) in Physics, 2011
University of Western Australia
BSc in Mathematics, 2009
University of Queensland

Experience

Marie Sklodowska-Curie Fellow

Scuola Normale Superiore

Sep 2023 – Present Pisa, Italy

My MSCA fellowship project is called ‘FORWARD’, and will focus on developing Bayesian methods of understanding the full, correlated error budget of 21cm experiments like HERA, EDGES and the SKA. This will focus primarily on developing models of our instruments, and propagating our uncertainties on these models through to parameter inference.

Research Scientist

Arizona State University

Oct 2018 – Aug 2023 Arizona

At ASU, I worked with the HERA interferometer and the EDGES global signal experiment, as well as leading development of the 21cmFAST simulation package. For HERA, I helped lead the Validation team, designing and running some of the most sophisticated instrumental simulations in the world. For EDGES, I have developed a new robust analysis pipeline to help confirm the potential first-ever detection of Cosmic Dawn.

Postdoctoral Researcher

Curtin University

Nov 2015 – Sep 2018 Western Australia

At ICRAR-Curtin, I worked within the EoR group, developing theoretical models in the context of the Murchison Widefield Array (MWA). I contributed to models of the ionosphere, as well improving statistical models of bright foregrounds.

Projects

FORWARD

FORWARD is the name of my Marie Sklodowska-Curie Fellowship. It’s not an acronym: it is short for “Forward-Models of Cosmic Dawn: connecting 21cm simulations to the real world”. I am performing the fellowship at Scuola Normale Superiore in Pisa, Italy.

EDGES

The Experiment to Detect the Global Eor Signal is a “global 21cm signal” experiment. It reported the first evidence of the very first stars in the Universe in 2018.

I develop EDGES’ analysis pipeline for everything from data formats to calibration to data reduction and interpretation. I am particularly interested in validating our pipeline with Bayesian statistical models.

HERA

The Hydrogen Epoch of Reionization Array is one of the largest radio interferometers in the world, and is looking to map the effects of the first stars, galaxies and black holes over the first billion years of the Universe.

I co-lead the Validation Team, developing increasingly realistic simulations of our observations at scale. I also lead the development of an interface to compute theoretical likelihoods on HERA data.

SKA

The SKA will be the largest radio telescope ever built, with a collecting area of over a square kilometre. It will be able to detect the faintest signals from the early Universe, and will be able to image the sky with unprecedented resolution.

I am a member of the EoR and Cosmic Dawn Science Working Group, contributing to the development of our tools and techniques, to be ready for the insane amount of data we’re going to get when SKA comes online.

21cmFAST

21cmFAST is the premiere semi-numerical 21cm cosmological simulator. It is currently used by every 21cm cosmology experiment to derive predictions of the spatial distribution of 21cm brightness temperature, to compare to observations.

I am a core developer in this project. My role has been primarily to wrap the fast C-code of the original simulator into Python, so that it can be more widely and easily used. This also has the benefit of adding a number of tests so that future development is safer and so that the code can be trusted by its many users.

Codes

Browse the different codes I have created or am heavily involved in developing.

21cmMC

21cmMC uses 21cmFAST to compare observations with theory, and predict astrophysical and cosmological parameters. This is a beast of a process, since it must run thousands of cosmological simulations to generate the predictions. Thus, 21cmMC is highly parallelized with MPI and is geared to run on supercomputers.

21cmMC was originally written by Brad Greig. My primary role has been to integrate it with 21cmFAST v3+, and to improve the interface and extensibility.

21cmFAST

21cmFAST is the premiere semi-numerical 21cm cosmological simulator. It is currently used by every 21cm cosmology experiment to derive predictions of the spatial distribution of 21cm brightness temperature, to compare to observations.

I am a core developer in this project. My role has been primarily to wrap the fast C-code of the original simulator into Python, so that it can be more widely and easily used. This also has the benefit of adding a number of tests so that future development is safer and so that the code can be trusted by its many users.