Computational simulation reveals speed of merging black holes

“Mergers generate gravitational waves, and an ensuing recoil can occur in the opposite direction, similar to the recoil of a gun,” mentioned the Phys.org report. 

The energy released by the recoil can propel the merging black hole into space at astounding speeds.

The report adds that the previous calculations by other researchers estimated that such black holes may reach maximal speeds of over 3,107 miles/sec (5,000 km/sec). 

The scientists did the calculations in this new work using supercomputer simulations to determine their speed after merging.  

One of the primary data points entered into the mathematical simulation was the angle at which the two black holes approached each other before merging. They considered 1,300 various angles, such as direct collisions and near flybys.

"We performed a series of 1381 full numerical simulations of high energy collision of black holes to search for the maximum recoil velocity after their merger," mentioned the study.

They discovered that in the best-case scenario, recoil should be able to send the combined black hole hurtling through space at around 28,500 kilometers per second. At this rate, a merged black hole would travel the distance between the Earth and the Moon in only 13 seconds.

The results have been reported in the journal Physical Review Letters.  

Study abstract:

We performed a series of 1381 full numerical simulations of high energy collision of black holes to search for the maximum recoil velocity after their merger. We consider equal mass binaries with opposite spins pointing along their orbital plane and perform a search of spin orientations, impact parameters, and initial linear momenta to find the maximum recoil for a given spin magnitude s. This spin sequence for s=0.4, 0.7, 0.8, 0.85, 0.9 is then extrapolated to the extreme case, s=1, to obtain an estimated maximum recoil velocity of 28,562±342  km/s, thus approximately bounded by 10% of the speed of light.