Davide Gerosa


Surrkick: Black-hole kicks from numerical-relativity surrogate models

This page contains supporting material and resources from:

  • Black-hole kicks from numerical-relativity surrogate models
    Davide Gerosa, Francois Hebert, Leo Stein
    arXiv:1802.04276 [gr-qc]

When using this material, please make reference to our paper.

Our code to extract black hole recoils from numerical relativity surrogate models is publicly available at github.com/dgerosa/surrkick. 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. You can try some functionalities with


More details on the code, what it does, how to use it, etc. are available on Sec. 5 of our paper and on github. Oh, and before you ask, surrkick is not a funny acronym, it’s just meant to say we’re extracting kicks from surrogate models…

Here below are animated versions of Fig. 2 in arXiv:1802.04276 [gr-qc]:

HD Left panel of Fig. 2 from 1802.04276

HD Middle panel of Fig. 5.1 from 1802.04276

HD Right panel of Fig. 5.1 from 1802.04276

Center of mass trajectory x(t) for three binary configurations as described in the legends. The circle markers on each curve correspond to t=0. The left panel shows a recoil due to mass asymmetry only: the center of mass oscillates in the orbital plane during the inspiral and is finally pushed after merger. The middle panel shows a complicated interplay of mass and spin asymmetry, with the initial oscillations being greatly distorted at merger by the superkick effect. Finally, the right panel shows the simpler trajectory of a binary receiving a very large kick of ∼ 3000 km/s. An animated version of this figure is available at davidegerosa.com/surrkick.

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Picture: train station in Berlin, Germany: things at the top need those at the bottom