Add BoostVelocity option to ShapeMap #6363
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| struct BoostVelocity { | ||
| using type = std::array<double, 3>; | ||
| static constexpr Options::String help = { | ||
| "Boost velocity to transform horizon with in Cartesian Kerr-Schild " |
| @@ -17,9 +17,10 @@ template <typename DataType> | |||
| Scalar<DataType> kerr_horizon_radius( | |||
| const std::array<DataType, 2>& theta_phi, const double mass, | |||
| const std::array<double, 3>& dimensionless_spin) { | |||
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Take the boost velocity as an argument here as well, can't hurt
| */ | ||
| template <typename DataType> | ||
| Scalar<DataType> kerr_schild_radius_from_boyer_lindquist( | ||
| const double boyer_lindquist_radius, | ||
| const std::array<DataType, 2>& theta_phi, double mass, | ||
| const std::array<double, 3>& dimensionless_spin); | ||
| const std::array<double, 3>& dimensionless_spin, | ||
| const std::array<double, 3>& boost_velocity); |
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Default this to zero, then you don't have to change some places where you call this function with zero boost.
| 1.0 / (1.0 - (square(boost_velocity_x) + square(boost_velocity_y) + | ||
| square(boost_velocity_z))); | ||
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| Scalar<DataType> unboosted_kerr_schild_radius = |
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Move this up and return it directly if the boost is zero.
| Scalar<DataVector> boosted_radius = Scalar<DataVector>{ | ||
| sqrt(square(get<0>(boosted_coords)) + square(get<1>(boosted_coords)) + | ||
| square(get<2>(boosted_coords)))}; |
| // Boosted horizon should be equivalent to applying Lorentz transformation | ||
| // on unboosted coordinates. | ||
| CHECK_ITERABLE_APPROX( | ||
| kerr_schild_radius_from_boyer_lindquist(r_plus, theta_phi, mass, |
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Maybe I have to think about this more, but I am confused about angles. The angles passed in here should be in the boosted frame I think. So these should be the angles you get when you transform the boosted Cartesian coords to polar coords.
| * Kerr-Schild coordinates and find that the boosted Kerr-Schild radius \f$r'\f$ | ||
| * as a function of angles satisfies | ||
| * \f[ | ||
| * r'^2 = r^2 (1 + \gamma^2 \left( \beta_x\cos\phi\sin\theta + |
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Are these angles in the boosted or unboosted frame? I think they should be in the boosted frame (see comment in the test below).
Proposed changes
Allows for boosted Kerr horizons in ShapeMap by adding a
boost_velocityargument togr::Solutions::kerr_schild_radius_from_boyer_lindquist. The previously returned Kerr-Schild radius is now Lorentz boosted before being returned. The new input optionBoostVelocity, which takes an array of three doubles, has been added toShapeMap.Code review checklist
make docto generate the documentation locally intoBUILD_DIR/docs/html.Then open
index.html.code review guide.
bugfixornew featureif appropriate.