Antikick in the head-on collision of two black holes

In this model [1], a smaller and a large black hole move linearly towards each other and collide head-on. The smaller black hole moves faster, has a high downward momentum and emits strong gravitational waves downwards. Since every action also produces a reaction, the overall system moves upwards - this is the "kick" (left part of Fig. 1).
The black hole produced by the merger initially is not spherical, but is deformed and has a type of “bump” at the top (central part of Fig. 1). To smooth this asymmetry and achieve the energetically more favourable spherical shape, more momentum is radiated upwards by means of gravitational waves: this "anti-kick" therefore decelerates the resulting black hole. It still moves upwards, albeit at a reduced speed (right part of Fig. 1).

Numerical simulation: P. Moesta, L. Rezzolla (Max Planck Institute for Gravitational Physics (Albert Einstein Institute))
Scientific visualization: M. Koppitz (Max Planck Institute for Gravitational Physics (Albert Einstein Institute) & Zuse Institute Berlin)

Note: These images are copyright by AEI, ZIB and ITP. Publication requires proper credits and written permission. Please contact aei_zib_images@aei.mpg.de in advance of publication or for higher-resolution versions.

1.
Luciano Rezzolla, Rodrigo P. Macedo and José Luis Jaramillo
Understanding the "anti kick" in the merger of binary black holes

Related press release: On the deceleration behaviour of black holes

Fig. 1: Kicking about in space: Researchers have modelled the collision of black holes (1). Thereby it was shown that the newly created black hole is initially deformed (2). To smooth this asymmetry and achieve the energetically more favourable spherical shape, more momentum is radiated upwards: this "anti-kick" decelerates the black hole slightly - it now continues to move with reduced speed (3). Zoom Image
Fig. 1: Kicking about in space: Researchers have modelled the collision of black holes (1). Thereby it was shown that the newly created black hole is initially deformed (2). To smooth this asymmetry and achieve the energetically more favourable spherical shape, more momentum is radiated upwards: this "anti-kick" decelerates the black hole slightly - it now continues to move with reduced speed (3). [less]
Zoom Image
Zoom Image

Zoom Image
Zoom Image
 
loading content