surrkick

Code and data release supporting

Black-hole kicks from numerical-relativity surrogate models. Davide Gerosa, Francois Hebert, Leo C. Stein. Phys. Rev. D 97, 104049 (2018). arXiv:1802.04276

Credits

You are welcome to use our software/data in your research. We kindly ask you to cite the paper above. If you want to cite this data release specifically, the DOI code is:

Installation

surrkick is a python module, uploaded to the Python Package index. Installation is as easy as

pip install surrkick

The SXS surrogate model NRSur7dq2 and a few other dependencies will be installed together with surrkick. If you don't have it already, you might need to manually install numpy beforehand (that's pip install numpy). You can try some functionalities with

import surrkick
surrkick.plots.minimal()

Main functions

The core of the code consists of a single class, surrkick, whose methods allow to extract radiated energy, linear momentum (kicks) and angular momentum from the underlying waveform approximant. The main methods are:

sur(): Instance of the surrogate class from NRSur7dq2
q: Binary mass ratio 0.5<=q<=1 (Default: q=1).
chi1: Spin vector of the heavier BH at t_ref (Default chi1=[0,0,0]).
chi2: Spin vector of the lighter BH at t_ref (Default chi2=[0,0,0]).
t_ref: Reference time -4500<=t_ref/M<=-100 (Default t_ref/M=100).
times: Time nodes -4500<=t_i/M<=-100
lmax: Largest available l-mode (lmax=4 in NRSur7dq2).
h(l,m): Modes of the complex GW strain.
hdot(l,m): Modes of the time derivative of the GW strain.
dEdt: Energy flux dE/dt.
Eoft: Radiated energy profile E(t).
Erad: Total radiated energy.
Moft: Mass profile M(t).
Mfin: Mass of the remnant BH.
dPdt: Linear momentum flux dP/dt.
Poft: Radiated linear momentum profile P(t).
Prad: Total radiated linear momentum.
voft: Recoil velocity profile v(t).
kickcomp: Kick velocity, vector.
kick: Kick velocity, magnitude vk
kickdir: Kick velocity, unit vector.
dJdt: Angular momentum flux dJ/dt.
Joft: Radiated angular momentum profile J(t).
Jrad: Total radiated angular momentum.
xoft: Center-of-mass trajectory x(t).

The class plots contains scripts to reproduce all figures and results in arXiv:1802.04276. You can explore its methods with, e.g. help(surrkick.plots).

Test

The source code for the surrkick.plots.minimal() method mentioned above is

import surrkick
import matplotlib.pyplot as plt
sk=surrkick.surrkick(q=0.5,chi1=[0.8,0,0],
    chi2=[-0.8,0,0])
print 'vk/c=', sk.kick
plt.plot(sk.times,sk.voft[:,0],label='x')
plt.plot(sk.times,sk.voft[:,1],label='y')
plt.plot(sk.times,sk.voft[:,2],label='z')
plt.plot(sk.times,surrkick.project(sk.voft,
    sk.kickdir),label='vk')
plt.xlim(-100,100)
plt.legend()
plt.show()

If you try it, you should get a printout that reads vk/c= 0.00384... and this plot: minimal

Movies

Here are some animations produced with surrkick. Also available in this Youtube playlist

https://github.com/user-attachments/assets/06724bb2-c7ea-43e8-aec0-4e033d1e2ac6

https://github.com/user-attachments/assets/d35acea3-f5f9-4996-bb74-ef760640f5b9

https://github.com/user-attachments/assets/24ee917d-e987-4baf-a231-853c59737757

Surrkick

Install / Use

README