Stephen Green

Contact

• workRoom B50d Mathematical Sciences
  University Park
  Nottingham
  NG7 2RD
  UK
• Stephen.Green2@nottingham.ac.uk
• https://www.stephenrgreen.com

Biography

2022 - present: Nottingham Research Fellow

2021 - 2022: Senior Scientist (Max Planck Institute for Gravitational Physics, Potsdam)

2017 - 2021: Junior Scientist (Max Planck Institute for Gravitational Physics, Potsdam)

2014 - 2017: Postdoctoral Researcher (Perimeter Institute for Theoretical Physics)

2012 -2014: CITA National Postdoctoral Fellow (University of Guelph, Canada)

2012: PhD in Physics (University of Chicago)

2005: BSc in Mathematics and Physics (University of Toronto)

Research Summary

My research is in gravitational wave astronomy---both signal modeling and data analysis. Gravitational waves were first detected in by the LIGO experiment in 2015, emitted during the merger of two… read more

Selected Publications

• SBERNA, LAURA, BOSCH, PABLO, EAST, WILLIAM E., GREEN, STEPHEN R. and LEHNER, LUIS, 2022. Nonlinear effects in the black hole ringdown: Absorption-induced mode excitation PHYSICAL REVIEW D. 105(6),
• DAX, MAXIMILIAN, GREEN, STEPHEN R., GAIR, JONATHAN, MACKE, JAKOB H., BUONANNO, ALESSANDRA and SCHOELKOPF, BERNHARD, 2021. Real-Time Gravitational Wave Science with Neural Posterior Estimation PHYSICAL REVIEW LETTERS. 127(24),
• GREEN, STEPHEN R., HOLLANDS, STEFAN and ZIMMERMAN, PETER, 2020. Teukolsky formalism for nonlinear Kerr perturbations CLASSICAL AND QUANTUM GRAVITY. 37(7),
• GREEN, STEPHEN R. and WALD, ROBERT M., 2011. New framework for analyzing the effects of small scale inhomogeneities in cosmology PHYSICAL REVIEW D. 83(8),

• View all publications

Current Research

My research is in gravitational wave astronomy---both signal modeling and data analysis. Gravitational waves were first detected in by the LIGO experiment in 2015, emitted during the merger of two black holes 1.3 billion light-years away. Since that time, nearly 100 such events have been detected by the LIGO-Virgo-KAGRA (LVK) network of observatories, as they continue to increase in sensitivity.

I am developing the use of probabilistic deep learning to rapidly analyse gravitational wave data. We use tools such as normalising flows to perform amortized Bayesian inference of source parameters given the observed data---including detailed uncertainty estimates (see figure below). These tools enable extremely fast and accurate inference to keep pace with ever-improving detectors. I am leading development of the Dingo parameter estimation code that implements these ideas, and I am a member of the LIGO Scientific Collaboration.

My theoretical research aims to develop accurate theoretical predictions for gravitational waves. This is based on Einstein's theory of general relativity. I am particularly focused on black-hole perturbation theory, and applications to the black-hole ringdown following a merger, and to extreme mass-ratio inspirals ("self-force").

Past Research

My PhD research (with Robert Wald, at the University of Chicago) was on the problem of averaging and backreaction in relativistic cosmology. It had been proposed that the nonlinear structure in the universe could (if properly taken into account when solving Einstein's equation) drive an overall acceleration of the universe---essentially explaining away Dark Energy. We developed a perturbative approach to take such effects into account and showed that such effects are negligible.

During postdocs at the University of Guelph and the Perimeter Institute, I worked on problems of turbulence and instabilities in general relativity. This includes turbulence around large AdS black holes, the superradiant instability of confined black holes, and the instability of global AdS.

Future Research

In the future, I am most interested in the LISA space-based gravitational wave observatory. This will consist of three satellites in a triangular configuration with 2.5 million kilometre arms, in orbit around the Sun behind the Earth. Due to its larger size, LISA will be sensitive to lower frequency sources than the LVK. With its increased sensitivity, LISA data will consist of many overlapping sources, including galactic binaries, supermassive black hole binaries, and extreme mass-ratio inspirals---all of which must be disentangled. My goals include extending the use of simulation-based inference / normalising flows methods to the more challenging LISA case, and building accurate signal models taking into account high-order effects.

• SBERNA, LAURA, BOSCH, PABLO, EAST, WILLIAM E., GREEN, STEPHEN R. and LEHNER, LUIS, 2022. Nonlinear effects in the black hole ringdown: Absorption-induced mode excitation PHYSICAL REVIEW D. 105(6),
• TOOMANI, VAHID, ZIMMERMAN, PETER, SPIERS, ANDREW, HOLLANDS, STEFAN, POUND, ADAM and GREEN, STEPHEN R., 2022. New metric reconstruction scheme for gravitational self-force calculations CLASSICAL AND QUANTUM GRAVITY. 39(1),
• WHITTAKER, TIM, EAST, WILLIAM E., GREEN, STEPHEN R., LEHNER, LUIS and YANG, HUAN, 2022. Using machine learning to parametrize postmerger signals from binary neutron stars PHYSICAL REVIEW D. 105(12),
• ORTIZ, NESTOR, CARRASCO, FEDERICO, GREEN, STEPHEN R., LEHNER, LUIS, LIEBLING, STEVEN L. and WESTERNACHER-SCHNEIDER, JOHN RYAN, 2022. Gamma-radiation sky maps from compact binaries JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS.
• DAX, MAXIMILIAN, GREEN, STEPHEN R., GAIR, JONATHAN, MACKE, JAKOB H., BUONANNO, ALESSANDRA and SCHOELKOPF, BERNHARD, 2021. Real-Time Gravitational Wave Science with Neural Posterior Estimation PHYSICAL REVIEW LETTERS. 127(24),
• GREEN, STEPHEN R. and GAIR, JONATHAN, 2021. Complete parameter inference for GW150914 using deep learning MACHINE LEARNING-SCIENCE AND TECHNOLOGY. 2(3),
• GREEN, STEPHEN R., HOLLANDS, STEFAN and ZIMMERMAN, PETER, 2020. Teukolsky formalism for nonlinear Kerr perturbations CLASSICAL AND QUANTUM GRAVITY. 37(7),
• GREEN, STEPHEN R., SIMPSON, CHRISTINE and GAIR, JONATHAN, 2020. Gravitational-wave parameter estimation with autoregressive neural network flows PHYSICAL REVIEW D. 102(10),
• BOSCH, PABLO, GREEN, STEPHEN R., LEHNER, LUIS and ROUSSILLE, HUGO, 2020. Excited hairy black holes: Dynamical construction and level transitions PHYSICAL REVIEW D. 102(4),
• GAGNON-BISCHOFF, JEREMIE, GREEN, STEPHEN R., LANDRY, PHILIPPE and ORTIZ, NESTOR, 2018. Extended I-Love relations for slowly rotating neutron stars PHYSICAL REVIEW D. 97(6),
• GREEN, STEPHEN R., HOLLANDS, STEFAN, ISHIBASHI, AKIHIRO and WALD, ROBERT M., 2016. Superradiant instabilities of asymptotically anti-de Sitter black holes CLASSICAL AND QUANTUM GRAVITY. 33(12),
• GREEN, STEPHEN R. and WALD, ROBERT M., 2016. A simple, heuristic derivation of our 'no backreaction' results CLASSICAL AND QUANTUM GRAVITY. 33(12),
• BOSCH, PABLO, GREEN, STEPHEN R. and LEHNER, LUIS, 2016. Nonlinear Evolution and Final Fate of Charged Anti-de Sitter Black Hole Superradiant Instability PHYSICAL REVIEW LETTERS. 116(14),
• GREEN, STEPHEN R., MAILLARD, ANTOINE, LEHNER, LUIS and LIEBLING, STEVEN L., 2015. Islands of stability and recurrence times in AdS PHYSICAL REVIEW D. 92(8),
• BALASUBRAMANIAN, VENKAT, BUCHEL, ALEX, GREEN, STEPHEN R., LEHNER, LUIS and LIEBLING, STEVEN L., 2015. Balasubramanian et al. Reply PHYSICAL REVIEW LETTERS. 115(4),
• YANG, HUAN, ZHANG, FAN, GREEN, STEPHEN R. and LEHNER, LUIS, 2015. Coupled oscillator model for nonlinear gravitational perturbations PHYSICAL REVIEW D. 91(8),
• BUCHEL, ALEX, GREEN, STEPHEN R., LEHNER, LUIS and LIEBLING, STEVEN L., 2015. Conserved quantities and dual turbulent cascades in anti-de Sitter spacetime PHYSICAL REVIEW D. 91(6),
• GREEN, STEPHEN R. and WALD, ROBERT M., 2014. How well is our Universe described by an FLRW model? CLASSICAL AND QUANTUM GRAVITY. 31(23),
• BALASUBRAMANIAN, VENKAT, BUCHEL, ALEX, GREEN, STEPHEN R., LEHNER, LUIS and LIEBLING, STEVEN L., 2014. Holographic Thermalization, Stability of Anti-de Sitter Space, and the Fermi-Pasta-Ulam Paradox PHYSICAL REVIEW LETTERS. 113(7),
• GREEN, STEPHEN R., CARRASCO, FEDERICO and LEHNER, LUIS, 2014. Holographic Path to the Turbulent Side of Gravity PHYSICAL REVIEW X. 4(1),
• GREEN, STEPHEN R., SCHIFFRIN, JOSHUA S. and WALD, ROBERT M., 2014. Dynamic and thermodynamic stability of relativistic, perfect fluid stars CLASSICAL AND QUANTUM GRAVITY. 31(3),
• GREEN, STEPHEN R. and WALD, ROBERT M., 2013. Examples of backreaction of small-scale inhomogeneities in cosmology PHYSICAL REVIEW D. 87(12),
• GREEN, STEPHEN R., MARTINEC, EMIL J., QUIGLEY, CALLUM and SETHI, SAVDEEP, 2012. Constraints on string cosmology CLASSICAL AND QUANTUM GRAVITY. 29(7),
• GREEN, STEPHEN R. and WALD, ROBERT M., 2012. Newtonian and relativistic cosmologies PHYSICAL REVIEW D. 85(6),
• PANG, BIJIA, PEN, UE-LI, MATZNER, CHRISTOPHER D., GREEN, STEPHEN R. and LIEBENDOERFER, MATTHIAS, 2011. Numerical parameter survey of non-radiative black hole accretion: flow structure and variability of the rotation measure MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. 415(2), 1228-1239
• GREEN, STEPHEN R. and WALD, ROBERT M., 2011. New framework for analyzing the effects of small scale inhomogeneities in cosmology PHYSICAL REVIEW D. 83(8),