Yu Liu

QuasiLocalMeasures regular spin measurement assumes that the black hole spin is roughly aligned with the z direction. A spin near the equatorial plane does not work well. In this case you'll have to use the coordinate spins (qlm_coordspinx, qlm_coordspiny, qlm_coordspinz); these are less accurate for distorted black holes, but will still work very well under these circumstances.

-erik

On Thu, Apr 22, 2021 at 10:43 PM 刘屿 yuliumutian@gmail.com wrote:

Dear Cactus users,

I am trying to simulate a precessing BBH system. When I analysed the mass of the black hole (qlm_mass), I found that the spin evolution (qlm_spin) is abnormal. [image: qlm_spin.png] The coordinate-base spin vector gives a value closer to what I set. [image: qlm_coordspin_norm.png] This is the initial parameters.

ADMMass = 0.9898872694943947 Mass Ratio = 1.0 separation = 10.4 spin1 = [-0.125 0. 0. ] spin2 = [0.125 0. 0. ] chi1 = [-0.5 0. 0. ] chi2 = [0.5 0. 0. ]

I tried different methods for finding the killing vector field (i.e. QuasiLocalMeasures::killing_vector_method), but it didn't work.

If the small black hole does not spin (spin2 = [0, 0, 0]), things will get better.

The following is the difference between my parfile and GW150914.rpar

$ diff GW150914.rpar BBH000.rpar 32,33c32,33 < D = 10.0 # Separation

< q = 36.0/29.0 # Mass ratio: q = mp/mm >= 1

...

D = 10.4 # Separation q = 1 # Mass ratio: q = mp/mm >= 1

35,38c35,38 < chip = [0, 0, 0.31] # Dimensionsless spin of + BH (x0 > 0, more massive) < chim = [0, 0, -0.46] # Dimensionsless spin of - BH (x0 < 0, less massive) < Pr = -0.00084541526517121; # Radial linear momentum

< Pphi = 0.09530152296974252; # Azimuthal linear momentum

...

chip = [-0.5, 0, 0] # Dimensionsless spin of + BH (x0 > 0, more

massive)

...

chim = [0.5, 0, 0] # Dimensionsless spin of - BH (x0 < 0, less

massive)

...

Pr = -0.000878483532190008 Pphi = 0.0927554222753844

261,265c261,265 < CoordinatesSymmetry::reflection_z = yes < CoordinatesSymmetry::stagger = no < Coordinates::symmetry = "+z bitant" < Coordinates::additional_symmetry_size = 1

< Coordinates::verbose = no

...

##CoordinatesSymmetry::reflection_z = yes ##CoordinatesSymmetry::stagger = no ##Coordinates::symmetry = "+z bitant" ##Coordinates::additional_symmetry_size = 1 ##Coordinates::verbose = no

552,553c552,553 < SphericalSurface::maxntheta = 66

< SphericalSurface::maxnphi = 124

...

SphericalSurface::maxntheta = 161 SphericalSurface::maxnphi = 320

559,560c559,560 < SphericalSurface::ntheta [2] = 41

< SphericalSurface::nphi [2] = 80

...

SphericalSurface::ntheta [2] = 161 SphericalSurface::nphi [2] = 320

565,566c565,566 < SphericalSurface::ntheta [3] = 41

< SphericalSurface::nphi [3] = 80

...

SphericalSurface::ntheta [3] = 161 SphericalSurface::nphi [3] = 320

571,572c571,572 < SphericalSurface::ntheta [4] = 41

< SphericalSurface::nphi [4] = 80

...

SphericalSurface::ntheta [4] = 161 SphericalSurface::nphi [4] = 320

633,634c633,638 < IOScalar::outScalar_reductions = "minimum maximum average" < IOScalar::outScalar_vars = "SystemStatistics::process_memory_mb"

---

...

IOScalar::outScalar_reductions = "minimum maximum average norm1

norm2"

...

IOScalar::outScalar_vars = " SystemStatistics::process_memory_mb ML_ADMConstraints::ML_Ham ML_ADMConstraints::ML_mom "

670c674

< IOHDF5::out2D_every = $out2d_every

...

IOHDF5::out2D_every = 0

Thank You Best Regards

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Yu Liu PhD Student Department of Astronomy Huazhong University of Science and Technology _______________________________________________ Users mailing list Users@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users