I'm a cosmologist working on mapping the large-scale structure of the Universe with radio and optical telescopes
I'm currently a Reader in Cosmology at the Jodrell Bank Centre for Astrophysics at the University of Manchester. Before that, I was a lecturer and then a Reader at Queen Mary University of London from 2018 - 2022. I was a postdoc in the Radio Astronomy Lab and BCCP at UC Berkeley from 2017 - 2018, a NASA Postdoctoral Program fellow at JPL/Caltech from 2015 - 2017, and a postdoc in theoretical astrophysics at the University of Oslo from 2013 - 2015. I did my DPhil (PhD) in Astrophysics at the University of Oxford from 2010 - 2013, and my undergraduate degree in Physics with Astrophysics at the University of Manchester from 2006 - 2010. I'm originally from Stoke-on-Trent in the UK.
I'm also a Visiting Academic at the Centre for Radio Cosmology at the University of the Western Cape, a member of the SKA Cosmology Science Working Group (Core Team) and the HERA collaboration (Executive Board and lead of the Stats working group), a Full Member of the LSST Dark Energy Science Collaboration (where I was formerly co-convener of the Theory and Joint Probes working group), a member of the MeerKLASS radio cosmology collaboration, and was previously a member of the Planck Collaboration as part of the LFI Core Team while in Oslo. I am also a member of the Institute of Applied Data Science at Queen Mary.
Aside from my research interests in theoretical cosmology, I've also been involved in the open source movement. I began contributing to Ubuntu around 2005, before moving on to work on documentation for the GNOME project. My roles have included coordinating the writing of user and developer documentation, training new contributors, and supervising students for the project's Women's Outreach Program. I've also co-authored a couple of books on Ubuntu, published by No Starch Press in 2010 and 2012.
My area of expertise is in theoretical cosmology and general relativity. I'm fascinated by the lumpy, inhomogeneous nature of the Universe that we live in, and how structures evolve and interact on large scales. One of the biggest puzzles in this area is the (relatively) recent finding that the expansion of the Universe appears to be accelerating. This is a very curious result, and I'd like to get to the bottom of it!
My technical interests are quite broad, and include:
Cosmology with intensity maps of the redshifted hydrogen 21cm line
General relativistic effects in large-scale structure observations and light propagation
Using secondary anisotropies and spectral distortions of the CMB as cosmological probes
Long-range peculiar velocity surveys and tests of gravity using the kinematic Sunyaev-Zel'dovich effect
Observational tests of the Cosmological Principle, and the averaging and backreaction problems
Bayesian statistics, stochastic processes, and computational physics
Below is a list of research projects that I've received funding for:
MapItAll — Illuminating the darkness with precision maps of neutral hydrogen across cosmic time (ERC Starting Grant, €1.67m, 2021-2025)
Astronomy Research at QM — Pushing 21cm to the (statistical) limit: A first EoR detection with an SKA Precursor (STFC Consolidated Grant, AGP/Astro Observations, £212k, 2020-2023)
Astronomy Research at QM — Relativistic effects in large-scale structure (STFC Consolidated Grant, AGP/Astro Theory, as co-I, £280k, 2021-2025)
HERA research — With UC Berkeley (subcontract, $278k, 2019-2022)
UNITY — Multi-wavelength simulations of relativistic cosmology (DiRAC 10th Call HPC allocation, 0.3M CPU-hours, 2018-2019)
NIAC/JPL — Direct Probe of Dark Energy Interactions with a Solar System Laboratory (NASA Innovative Advanced Concepts, Phase I Step B study, as Co-I, up to $125k, 2016)
This is a list of my scientific publications to date. You can also find listings on SPIRES, Google Scholar, and arXiv. My ORCID is 0000-0001-5668-3101. Some of the computer code used in these papers is available online.
Published and submitted papers are listed below, or you can skip to the list of white papers or conference proceedings .
This is a list of (unpublished) white papers and technical reports that I have contributed to.
This is a list of my conference proceedings.
I try to make all of my scientific code, or at least a substantial fraction of it, publicly available. This enables other people to reproduce and check my work if they want to. It also allows them to build off my code and do cool new things, rather than having to spend months solving problems that I may have already solved. That's the theory, anyway. Much of the code is written in Python, C++, and/or Fortran 90, and housed on GitHub or Gitlab.
Here are some of my publicly-available scientific codes:
Fisher forecasting for 21cm surveys
Generates forecasts for a wide range of 21cm IM experiment types and cosmological parameters.
21cm power spectrum estimation
Implements optimal quadratic power spectrum estimator for delay spectra; part of the HERA stack.
Validated cosmo theory predictions
Stringently-validated theoretical predictions for cosmological observables, for LSST DESC.
Simple intensity map simulator
Gaussian/log-normal intensity map and galaxy survey simulator, including systematic effects.
Visibility simulator for TensorFlow
Simple interferometeric visibility simulator written for GPU + CPU using TensorFlow.
Statistical galaxy-halo model
Analytic model linking galaxy properties to dark matter halos using a chain of statistical distributions.
Monte Carlo quintessence models
Randomly constructs quintessence potentials and solves for cosmological observables.
Modified gravity Boltzmann code
Modified version of the CLASS code that includes phenomenological MG parametrisations.
Relativistic exact solutions in LTB
Solves background, geodesic equations, and scattering in Lemaître-Tolman-Bondi spacetimes.
Full-sky CMB Gibbs sampler
Estimates the CMB + foreground joint posterior using Gibbs sampling and constrained realisations.
Flat-sky CMB Gibbs sampler
Gibbs sampler for separating the CMB from localised secondary anisotropies on small patches of sky.
I lead the HERA research group at JBCA, which focuses on statistical analysis of the HERA data, including power spectrum estimation and simulations. I also co-lead research groups in 21cm cosmology at UWC (with Prof. Mario Santos) and relativistic large-scale structure at QMUL (with Dr Chris Clarkson). The following is a list of current group members:
Former group members:
Samir Choudhuri (PDRA 2019-2022), now faculty at IIT Madras.
I most recently taught SPA6311 Physical Cosmology (3rd year) at QMUL, and previously taught SPA5201 Physics Laboratory (2nd year). I also supervise projects for SPA6776 (Extended Independent Project) and SPA6913 (Physics Review Project), both in the 3rd year.
I was previously director of the new BSc and MSci programme in Physics with Data Science at QMUL, which launched in 2021.
Slides on Cosmology with SKA and Pathfinders from the 2016 INAF Scuola Lucchin summer school [20MB].
Slides on Gibbs sampling and Gaussian constrained realisations [7MB].
(Includes students jointly supervised with others.)
Isabelle Ye (PhD, QMUL, 2021-)
Geoff Murphy (PhD, UWC, 2021-)
Katrine Glasscock (PhD, QMUL, 2021-)
Chris Addis (PhD, QMUL, 2021-)
Fraser Kennedy (PhD, QMUL, 2019-)
Caroline Guandalin (PhD, U. São Paulo, 2018-2021)
Mikael Bull Steen (PhD, Oslo, 2014-2016)
(Includes students jointly supervised with others.)
Dimos Zografos (MSc, QMUL, 2020-2021)
Kabelo Malapane (Masters, U. Western Cape, 2020-)
Ankur Dev (Masters, QMUL, 2019-2020)
Tim Oates (MSc, QMUL, 2019-2020)
Alex Reedy (MSc, QMUL, 2019-2020)
Matt Warner (Masters, QMUL, 2019-2020)
Bradley Cooper-Barnard (MSc, QMUL, 2019)
Thomas Murray (MSc, QMUL, 2019)
Lisa McBride (Masters, SFSU, 2018)
Magnus Fagernes Ivarsen (Masters, Oslo, 2015-16)
Robert Olav Fauli (Masters, Oslo, 2014-15)
Thomas Boyer (Masters, ENSTA Paris, 2021)
Romain Pioch (Masters, ENSTA Paris, 2020)
Kai-Hei Chan (undergrad, Hong Kong University, 2019)
Peter Pan (undergrad, QMUL, 2019)
Matthieu Vilatte (Masters, ENSTA Paris, 2019)
Richelle Xavier (undergrad, Warwick, 2019)
Shaunak Modak (undergrad, UC Berkeley, 2018)
Duncan Rocha (undergrad, Harvey Mudd College, 2018)
Louis Penafiel (undergrad, UC Riverside, 2017)
Elizabeth Kimura (undergrad, Santa Monica College, 2017)
Amanda Brown (undergrad, Princeton, 2016)
I've been involved in public outreach since the very start of my scientific career. Science is an extremely important part of the shared culture of humanity, and I believe that professional scientists have a duty to put their work into the public commons in an effective way, so that everyone can share in our discoveries.
I was the graduate public outreach coordinator at Oxford Astrophysics while I was a DPhil student there. We used to run open evenings for schools and the general public, using the Philip Wetton telescope on the roof of the Denys Wilkinson Building, and various cool Zooniverse projects.
We also initiated a rather successful annual space science festival called Stargazing Oxford, to tie in with the BBC's Stargazing Live programmes.
I've also been interviewed a few times here and there, and occasionally comment on science news stories (and opinion) in the press, as well as doing the odd podcast now and then.
The pinnacle of my media career, however, was when I appeared (for approximately one second) in the 2013 feature documentary Hawking. You can find me at around 40 minutes in, eating soup and waving my hands.
RHINO is a prototype 21cm global signal experiment that we are developing at Jodrell Bank Observatory. It's based on a large horn antenna operating at around 70 MHz (4m wavelength). While horns have to be gigantic at these wavelengths, they offer excellent control over the beam pattern, cross-polarisation, side- and backlobes etc.
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