Numerical approaches to Radiative Backreaction in General Relativity
Lead Research Organisation:
University of Cambridge
Department Name: Applied Maths and Theoretical Physics
Abstract
This project focuses on numerically solving the nonlinear partial differential equations of general relativity (GR) coupled to non-trivial field theories that exhibit dynamical topological solutions (such as vortex-lines/strings and domain walls). The aim is to calculate the resulting gravitational radiation, as well as the radiative backreaction on these extended objects, using newly developed automatic mesh refinement (AMR) codes. By analogy with electromagnetic waves, the purppose is to advance the mathematical understanding of backreaction processes in GR both numerically and analytically, notably characterising the time evolution of the radiation spectrum. An important component of this project will be collaboration with Intel on the optimization of these AMR GR codes for many-core HPC architectures. The project will also advance high performance data analytics through in-situ (or "on the fly") visualization of the evolving pde solutions. (This represents the development of pioneering collaborative projects being pursued at the DAMTP Intel Parallel Computing Centre, which have been demonstrated at SC'15 and ISC'16.) Note: SC'15 was the Supercomputing 2015 conference in Austin, Texas in November 2015 and ISC'16 the International Supercomputing 2016 conference in Frankfurt this June (the main high performance computing meetings worldwide).
Organisations
- University of Cambridge (Lead Research Organisation)
- QUEEN MARY UNIVERSITY OF LONDON (Collaboration)
- UNIVERSITY OF OXFORD (Collaboration)
- Argonne National Laboratory (Collaboration)
- Université Catholique de Louvain (Collaboration)
- KING'S COLLEGE LONDON (Collaboration)
- Intel Corporation (UK) Ltd (Student Project Partner)
People |
ORCID iD |
| Edward Shellard (Primary Supervisor) | |
| Amelia Drew (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/P510440/1 | 01/10/2016 | 30/09/2022 | |||
| 1783810 | Studentship | EP/P510440/1 | 01/10/2016 | 30/09/2020 | Amelia Drew |
| Description | The Nobel-Prize-winning detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015 opened up a brand new window into observational cosmology, catalysing research into gravitational wave signatures from a wide range of astrophysical and cosmological sources. For this work, I focus on calculating accurate observational signatures from topological `cosmic' strings which arise if the rapid cooling of the Early Universe triggers a `phase transition', similar to water freezing to ice. Cosmic strings are strongly tied to fundamental physics; detection will enable us to draw deep conclusions about particle physics and the underlying structure of space and time. Accurate signal templates are essential for maximising discovery potential with ongoing LIGO searches as well as the space-based Laser Interferometer Space Antenna (LISA) and the Einstein Telescope. Further to this, topological strings provide insight into a fundamental question of modern cosmology and particle physics; the identity of dark matter. This is matter that has not been directly observed but has been inferred from astrophysical observations and is predicted to make up around 85% of the total matter in our Universe. Massless 'axion' radiation emitted from `axion strings,' mathematical equivalents of cosmic strings, has been proposed as a dark matter candidate. Numerical simulations of cosmic strings are significantly computationally challenging; the ratio between the string width and the scale of the Universe is far beyond the capability of current simulations to resolve. My research addresses this using a computational technique called `adaptive mesh refinement' (AMR), which allows the numerical simulation grid to adapt to the scale of the problem. I have performed the first AMR simulations of `global' cosmic strings, exploring and analysing approximately 100 single string simulations using the code GRChombo, for which I am a core developer (http://www.grchombo.org/collaborators). Performing an in-depth analysis of the axion radiation and string evolution, we conclude that the evolution of global strings tends towards the behaviour predicted analytically in the thin-string limit, with radiation damping. |
| Exploitation Route | We have provided a significant step towards accurate prediction of cosmic string signatures using gravitational waves. The outcomes of the project thus far can be used by LIGO (the Laser Interferometer Gravitational-Wave Observatory) and LISA (the Laser Interferometer Space Antenna) Collaborations to aid with understanding these objects. |
| Sectors | Other |
| Description | Gonville and Caius Travel Grant |
| Amount | £750 (GBP) |
| Organisation | University of Cambridge |
| Department | Gonville and Caius College |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 06/2017 |
| End | 11/2019 |
| Description | Junior Research Fellowship |
| Amount | £94,700 (GBP) |
| Organisation | University of Cambridge |
| Department | Homerton College |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 10/2020 |
| End | 09/2024 |
| Description | GRChombo |
| Organisation | Argonne National Laboratory |
| Country | United States |
| Sector | Public |
| PI Contribution | Introduction of new features to the GRChombo code and contribution to ongoing discussions on ways to improve code speed and efficiency, including with researchers at Lawrence Berkeley National Laboratory. |
| Collaborator Contribution | Continued development of the GRChombo code including introduction of new features, streamlining the code and keeping the public version up to date, as well as intellectual input into numerical problems. We meet 3 times a year to keep each other updated on the science applications and coding updates, as well as to teach new users. |
| Impact | All simulations in arXiv:1910.01718 were performed using GRChombo, providing quantitative results on the evolution of global cosmic strings. |
| Start Year | 2017 |
| Description | GRChombo |
| Organisation | Catholic University of Louvain |
| Country | Belgium |
| Sector | Academic/University |
| PI Contribution | Introduction of new features to the GRChombo code and contribution to ongoing discussions on ways to improve code speed and efficiency, including with researchers at Lawrence Berkeley National Laboratory. |
| Collaborator Contribution | Continued development of the GRChombo code including introduction of new features, streamlining the code and keeping the public version up to date, as well as intellectual input into numerical problems. We meet 3 times a year to keep each other updated on the science applications and coding updates, as well as to teach new users. |
| Impact | All simulations in arXiv:1910.01718 were performed using GRChombo, providing quantitative results on the evolution of global cosmic strings. |
| Start Year | 2017 |
| Description | GRChombo |
| Organisation | King's College London |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Introduction of new features to the GRChombo code and contribution to ongoing discussions on ways to improve code speed and efficiency, including with researchers at Lawrence Berkeley National Laboratory. |
| Collaborator Contribution | Continued development of the GRChombo code including introduction of new features, streamlining the code and keeping the public version up to date, as well as intellectual input into numerical problems. We meet 3 times a year to keep each other updated on the science applications and coding updates, as well as to teach new users. |
| Impact | All simulations in arXiv:1910.01718 were performed using GRChombo, providing quantitative results on the evolution of global cosmic strings. |
| Start Year | 2017 |
| Description | GRChombo |
| Organisation | Queen Mary University of London |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Introduction of new features to the GRChombo code and contribution to ongoing discussions on ways to improve code speed and efficiency, including with researchers at Lawrence Berkeley National Laboratory. |
| Collaborator Contribution | Continued development of the GRChombo code including introduction of new features, streamlining the code and keeping the public version up to date, as well as intellectual input into numerical problems. We meet 3 times a year to keep each other updated on the science applications and coding updates, as well as to teach new users. |
| Impact | All simulations in arXiv:1910.01718 were performed using GRChombo, providing quantitative results on the evolution of global cosmic strings. |
| Start Year | 2017 |
| Description | GRChombo |
| Organisation | University of Oxford |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Introduction of new features to the GRChombo code and contribution to ongoing discussions on ways to improve code speed and efficiency, including with researchers at Lawrence Berkeley National Laboratory. |
| Collaborator Contribution | Continued development of the GRChombo code including introduction of new features, streamlining the code and keeping the public version up to date, as well as intellectual input into numerical problems. We meet 3 times a year to keep each other updated on the science applications and coding updates, as well as to teach new users. |
| Impact | All simulations in arXiv:1910.01718 were performed using GRChombo, providing quantitative results on the evolution of global cosmic strings. |
| Start Year | 2017 |
| Description | Discovery Channel: 'The Universe Unravelled in association with the Stephen Hawking Centre' |
| Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | One-on-one on-camera interviews for a series filmed by the Discovery Channel about cosmology and general relativity. Explained general relativity and cosmic strings in a way that is accessible and informative for a public audience. Will appear in 4 episodes to be aired in 2020, impact to be determined. |
| Year(s) Of Engagement Activity | 2019 |
| Description | Exhibitioner for HPE at SC18 Conference (supercomputing) |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | I was an exhibitioner for HPE using simulations from my research to demonstrate in-situ visualisation with Paraview Catalyst and the Intel Rendering Framework to industry experts. |
| Year(s) Of Engagement Activity | 2018 |
| Description | Exhibitor at SIGGRAPH |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Exhibitor at SIGGRAPH Conference in Los Angeles, demonstrating the Intel Rendering Framework for Intel's CREATE event. |
| Year(s) Of Engagement Activity | 2019 |
| URL | https://newsroom.intel.com/news/siggraph-intels-vision-exascale-class-content-creation-1000x-perform... |
| Description | Hewlett Packard Enterprise Promotional Video with Stephen Hawking |
| Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | I gave an interview with HPE on the benefits of in-memory computing to cosmological research. Excerpts from the interview were featured in a promotional video with Stephen Hawking and other members of Centre for Theoretical Cosmology. The video was uploaded onto youtube and was also linked from Stephen Hawking's facebook page (https://www.facebook.com/watch/?v=1606880102732414). |
| Year(s) Of Engagement Activity | 2017 |
| URL | https://www.youtube.com/watch?v=MgGhfuxUc44 |
| Description | Panellist for Gravitational Wave Probes of Fundamental Physics Workshop, Amsterdam |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Invited participation in panel on numerical relativity at workshop "Gravitational Wave Probes of Fundamental Physics" in Amsterdam. |
| Year(s) Of Engagement Activity | 2019 |
| Description | Talk at BritGrav19, Durham University |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Radiation from Global Topological Strings using Adaptive Mesh Refinement |
| Year(s) Of Engagement Activity | 2019 |
| Description | Talk at Cambridge-LMU Cosmology Meeting, LMU (Ludwig-Maximillians-Universitat) |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Axion Strings and Dark Matter |
| Year(s) Of Engagement Activity | 2019 |
| Description | Talk at Cosmic Topological Defects: Dynamics & Multi-Messenger Signatures Workshop, Leiden |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Radiation from Global Topological Strings using Adaptive Mesh Refinement |
| Year(s) Of Engagement Activity | 2018 |
| Description | Talk at Cosmology Journal Club, DAMTP, University of Cambridge |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Radiation from Global Topological Strings using Adaptive Mesh Refinement |
| Year(s) Of Engagement Activity | 2020 |
| Description | Talk at DAMTP, University of Cambridge, General Relativity Seminar |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Radiation from Global Topological Strings using Adaptive Mesh Refinement |
| Year(s) Of Engagement Activity | 2019 |
| Description | Talk at Gravitational Wave Proves of Fundamental Physics Workshop, Amsterdam |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Radiation from Global Topological Strings using Adaptive Mesh Refinement |
| Year(s) Of Engagement Activity | 2019 |
| Description | Talk at Lawrence Berkeley National Laboratory, Berkeley |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Radiation from Global Topological Strings using Adaptive Mesh Refinement |
| Year(s) Of Engagement Activity | 2019 |
| Description | Talk at Numerical Relativity beyond General Relativity Conference, Benasque |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Talk: Observational Signatures from Cosmic and Axion Strings |
| Year(s) Of Engagement Activity | 2018 |
| Description | Talk at School on Gravitational Waves for Cosmology and Astrophysics, Benasque |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Postgraduate students |
| Results and Impact | Talk: Primordial Gravitational Wave Signatures from Cosmic Strings |
| Year(s) Of Engagement Activity | 2017 |
| Description | Women in STEM |
| Form Of Engagement Activity | A magazine, newsletter or online publication |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | Featured in University of Cambridge #WomenInSTEM campaign, Q&A on University homepage and social media channels. |
| Year(s) Of Engagement Activity | 2019 |
| URL | https://www.cam.ac.uk/research/news/women-in-stem-amelia-drew |