ACFD · Acoustical and Canonical Fluid Dynamics in numerical general relativity
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2017-08-15 → 2020-01-30
- EU contribution
- €198,481
- Participants
- 2
- Scheme
- MSCA-IF-GF
Lines connect the coordinator with its partners.
Results in brief
Acoustical and Canonical Fluid Dynamics in numerical general relativity
What is the problem/issue being addressed? Binary neutron stars are astrophysical scale particle colliders, where all four fundamental forces come into play. Gravitational and electromagnetic waves, emitted during their inspiral and merger, carry valuable information about weak and strong nuclear interactions in their interior, where matter reaches the most extreme densities known in nature. Detection and parameter estimation of gravitational wave signals requires precise modelling of their sources. Numerical relativity and computational fluid dynamics are vital for simulating the inspiral of these systems and computing their gravitational waves. Why is it important for society? The first observed event, GW170817, had striking implications. It resolved the 50-year mystery of the origin of short gamma-ray bursts; it provided strong evidence for mergers as the main source of half the heaviest elements (the r-process elements); and gave an independent measurement of the Hubble constant. Future events, from galaxies not too far away, can also address a major goal of multimessenger astrophysics: From the imprint of tides on inspiral waveforms, we can measure the radius and tidal deformation of the inspiraling stars and infer the behavior of cold matter above nuclear density. What are the overall objectives? We develop a new, well-posed formulation of relativistic fluid dynamics, based on Hamilton's principle. We utilize this canonical formulation of the Euler-Einstein system in order to perform high-precision computational fluid dynamic simulations in numerical general relativity. The programme contributes towards a deeper understanding of fluid dynamics in curved spacetime, and how Kelvin's circulation theorem, Helmholtz's third theorem, and other the relevant features imprint themselves in gravitational waveforms. It explores the utility of such waveforms as probes of dense matter physics.
Data: CORDIS, © European Union
Project objective
The motion of strongly gravitating fluid bodies is described by the Euler-Einstein system of partial differential equations, combining fluid dynamics with general relativity. Centuries after their advent, the solution to these equations remains mathematically and computationally difficult, and the break-down of well-posedness on the boundary interface between fluid and vacuum remains a challenging open problem. The problem manifests itself in numerical simulations of binary neutron-star inspiral. The program will focus on formulating and implementing novel, well-posed Hamiltonian hydrodynamic schemes, suitable for inspiral simulations and gravitational-wave detector applications, with promising mathematical and computational applications in academia and industry. The scheme will use a variational principle by Carter-Lichnerowicz stating that barotropic fluid motions are conformally geodesic, a corollary of Kelvin's circulation theorem stating that initially irrotational flows remain irrotational, and Christodoulou's acoustic metric approach adopted to 3+1 numerical general relativity, in order to evolve the canonical momentum of a fluid element via Hamilton's equations. The recent observation of the inspiral and merger of binary black holes by the LIGO-Virgo collaboration, which marked the beginning of the era of gravitational wave astronomy, makes this work very timely: additional observations from binary neutron star or black hole–neutron star binary mergers are anticipated over the next years. The proposed research represents a coherent program aimed at mathematically and computationally exploring the theory of neutron stars, in order to improve our understanding of fundamental physical laws and reveal how nature operates on scales where our current understanding breaks down. Improvements in calibrated semi-analytical neutron-star gravitational waveforms can be directly deployed in the LIGO-Virgo search and parameter estimation pipelines.
Original text from CORDIS.
Participants
- THE CHANCELLOR MASTERS AND SCHOLARS OF THE UNIVERSITY OF CAMBRIDGE · CAMBRIDGECoordinatorUnited Kingdom
- THE BOARD OF TRUSTEES OF THE UNIVERSITY OF ILLINOIS · UrbanaUnited States
Links
Data: CORDIS, © European Union