Two black holes merged into the new one, and got a high speed ‘kick’

A newly formed black hole was launched at a speed of about 5 million kilometers per hour, thanks to gravitational waves.

Key Takeaways

1. Gravitational waves propelled a newly formed black hole at incredibly high speed, similar to a cosmic ‘kick.’
2. The black hole’s speed reached about 5 million kilometers per hour, equivalent to 200 times the speed of light.
3. This is the first time a large black hole kick has been observed using gravitational waves, making it a groundbreaking discovery.
4. Dense stellar environments, like globular clusters, have a low likelihood of containing kicked black holes due to their rapid escape.
5. Understanding black hole kicks could explain the formation of massive stellar-mass black holes observed in mergers.

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High-Speed Cosmic Kick: A New Black Hole Discovery

A newly formed black hole recently received a high-speed “kick,” thanks to gravitational waves, which propelled it at about 5 million kilometers per hour—roughly 200 times the speed of light. This surprising discovery was made through data collected by gravitational wave observatories LIGO and Virgo. These observatories detected spacetime ripples produced by the coalescence of two black holes on January 29, 2020, revealing the large recoil effect.

When two black holes spiral inward and merge, they emit gravitational waves that stretch and squeeze space. If these waves are directed in one particular direction, the black hole created from the merger will recoil in response. This effect, similar to how a gun kicks back after firing, propelled the newly formed black hole at an astonishing speed.

Researchers, led by astrophysicist Vijay Varma, delved into the data from LIGO and Virgo to analyze whether such a large kick was possible. By comparing the observed data with computer simulations based on general relativity, they determined that the black hole’s massive escape was indeed a reality.

Implications of the High-Speed Kick

The newly ejected black hole’s trajectory raises questions about its future. For black holes that merge in crowded stellar environments like globular clusters, the likelihood of staying within the cluster is minimal—only about 0.5%. In contrast, black holes in nuclear star clusters have an 8% chance of remaining.

Understanding these kicks has implications for the formation of massive stellar-mass black holes. Previously observed mergers of black holes with unexpectedly high masses might have occurred because of this high-speed escape mechanism, limiting the possibility of subsequent mergers.

While smaller kicks in black holes have been observed previously through gravitational waves, this is the first instance of detecting a significant black hole kick. Similar theoretical predictions were made by researchers, which were validated through this observation. Gravitational waves offer a cleaner and more direct way to study these events compared to traditional observations using light.