I am a Senior Research Fellow in Cosmology based in the School of Mathematics and Physics. I work on making maps of the positions and motions of millions of galaxies in our Universe to uncover how it has evolved since the Big Bang. Current observations suggest 95% of our Universe consists of ellusive Dark Matter and Dark Energy; we can detect these by the influence they have on the light from galaxies, stars and that permeates the background Universe itself, but they don't emit light themselves and we have no idea yet what they are. My research seeks to uncover these using the largest galaxy surveys in the world.
I have been involved in planning, carrying out, and analysing a large number of these surveys. I currently working groups in the American-led Dark Energy Spectroscopic Instrument (DESI) project, the WALLABY survey based in Western Australia, and the 4MOST Hemisphere Survey (4HS) which will be carried out from Chile. Combined, these will produce the most detailed maps of galaxy positions and motions ever created --- over 40,000,000 unique galaxies!
My personal research makes use of state-of-the art computing techniques to simulate the distributions of these galaxies, their properties, and how fast they are moving. I then analyse these distributions using different statistical techniques and compare to the real data. The properties of Dark Matter and Dark Energy and all the other things that make up our Universe can then be extracted by modelling these statistics with theoretical models, or looking for discrepancies between the simulations and the data. My hope is that by doing so, we are currently on the cusp of uncovering something fundamental about how the Universe came to be the way it is today, and what will happen to it in the future.
Academic Background
Undergraduate: MPhys 1st Class Honours - University of Sussex, 2008-2012
Postgraduate: PhD - University of Portmouth, 2012-2016
Research Associate - University of Western Australia, 2015-2019
Research Fellow in Cosmology - University of Queensland, 2019-
I am a Cosmologist studying the properties of the Universe on the largest scales.
By mapping the positions of millions of galaxies, I investigate the unknown physics of the dark energy which drives the evolution of the Universe today, and the physics just after the Big Bang, when the ripples which grew under gravity to become galaxies were created.
I am actively participating in the key experiments designed to understand dark energy and gravity. I am co-chair of the Dark Energy Spectroscopic Instrument (DESI) lensing working group, and an active member of the Vera Rubin Observatory (LSST) and the Dark Energy Survey (DES). In the past, I had led science with the Sloan Digital Sky Survey, one of the major quests of contemporary physics that has spurred advancement in answering a range of fundamental questions about the origins of the universe.
I am passionate about communicating top-level research ideas to audiences outside our immediate academic sub-community. I have experience on a variety of media, including radio, public talks and lectures to local schools, science festivals and amateur astronomy groups, outreach activities at Stargazing Live events, as well as through written pieces.
I am an advocate for making STEM field accessible to everyone. During my career, I took part into different initiatives aiming to reduce structural barriers faced by different minorities in academia and inspire the next generation of STEM careers. I am part of the Women in Science Association with the aim to foster a community for young women in STEM, within and beyond the academic community. I worked and volunteered at N.G.O. centres, in Italy and Australia supporting young students to overcome educational inequality caused by poverty and other conditions.
Since 2021 I am on the Early Career Chapter committee for the Astronomical Society of Australia (ASA) to promote and assist the career development of early and mid-career researchers in the Australian astronomy community. I am also part of the Wellbeing ambassador program at University of Queensland, to promote and assist the career development of early and mid-career researchers in the Australian astronomy community.
Dr Sarah Sweet's research interests are in astrophysics, in the field of galaxy evolution. She received her PhD from the University of Queensland in 2014. Dr Sweet then worked at the Australian National University and at Swinburne University of Technology, before returning to UQ as a Lecturer in Astrophysics in 2020. She was awarded an Australian Research Council DECRA Fellowship in 2022 and became a Senior Lecturer in 2023.
