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SpECTRE
v2025.08.19
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Gravitational self-force of a small gravitating body in a Kerr background. More...
#include <FirstOrderSystem.hpp>
Public Types | |
| using | primal_fields = tmpl::list< Tags::MMode > |
| using | primal_fluxes = tmpl::list<::Tags::Flux< Tags::MMode, tmpl::size_t< 2 >, Frame::Inertial > > |
| using | background_fields = tmpl::list< Tags::Alpha, Tags::Beta, Tags::GammaRstar, Tags::GammaTheta > |
| using | inv_metric_tag = void |
| using | fluxes_computer = Fluxes |
| using | sources_computer = Sources |
| using | modify_boundary_data = ModifyBoundaryData |
| using | boundary_conditions_base = elliptic::BoundaryConditions::BoundaryCondition< 2 > |
Static Public Attributes | |
| static constexpr size_t | volume_dim = 2 |
Gravitational self-force of a small gravitating body in a Kerr background.
Extension of the ScalarSelfForce::FirstOrderSystem to the gravitational case. We solve a 2D elliptic equation for the 10 independent components of the symmetric m-mode field \((\Psi_m)_{ab}\). The two dimensions are a radial and angular coordinate, specifically the tortoise radius \(r_\star\) and polar angle \(\theta\). We parametrize the 2D elliptic equations as:
\begin{equation} -\Delta_m (\Psi_m)_{ab} = -\partial_i F^i_{ab} + \beta_{ab}^{cd} (\Psi_m)_{cd} + \gamma_{iab}^{cd} F^i_{cd} = 0 \end{equation}
with the flux
\begin{equation} F^i_{ab} = \{\partial_{r_\star}, \alpha \partial_\theta\} (\Psi_m)_{ab} \text{,} \end{equation}
where \(\alpha\), \(\beta_{ab}^{cd}\), and \(\gamma_{iab}^{cd}\) are coefficients that define the elliptic equations. The particular coefficients for a circular equatorial orbit in Kerr are implemented in GrSelfForce::AnalyticData::CircularOrbit.
See ScalarSelfForce::FirstOrderSystem for a description of the regularization and modified boundary data.
Once the 2D elliptic equations are solved for a given m-mode, the contribution to the self-force can be extracted from the gradient of \((\Psi_m)_{ab}\) at the location of the small body. These self-force contributions are then summed over all m-modes up to some cutoff. The resulting self-force can be used to drive a quasi-adiabatic inspiral to generate waveforms. For details and more references see [158] for now (more references will be added when they are published).