How fast do black holes move
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How Fast Do Black Holes Move?
Recoil Velocities in Binary Black-Hole Mergers
Kick Velocities in Nonspinning and Spinning Binaries
Black holes can achieve significant velocities due to recoil effects during binary mergers. For nonspinning binaries, kick velocities are typically a few hundred kilometers per second (km/s) . When spins are involved, these velocities can increase substantially. For instance, spinning configurations can result in kick velocities around 500 km/s, with predictions suggesting a maximum kick of up to 1300 km/s . However, more extreme scenarios, such as equal-mass binaries with antialigned spins in the orbital plane, can produce kick velocities as high as 2500 km/s 17.
Asymmetry in Gravitational Radiation
The asymmetry in the emitted gravitational radiation during the final stages of a binary-black-hole merger is a key factor in determining the recoil velocity. For nonspinning binaries with unequal masses, kick velocities can reach approximately 175 km/s when the mass ratio is around 0.36 . In cases where the black holes have unequal spins that are antialigned and parallel to the orbital angular momentum, velocities can be as high as 440 km/s .
Black Hole Birth Kicks
Natal Kicks from Supernovae
Black holes can also receive kicks at birth due to asymmetric mass ejection or neutrino emission during core-collapse supernovae. Observations of low-mass X-ray binaries suggest that these natal kicks do not typically exceed 100 km/s, although higher velocities are not entirely ruled out .
Dynamics of Moving Black Holes
Interaction with Surrounding Medium
Moving black holes interact with their surroundings in unique ways. For instance, a black hole moving at relativistic speeds through a cold medium can appear surrounded by a bright "ring" due to energy transfer from the black hole to the surrounding radiation . This phenomenon highlights the complex dynamics and energy interactions involving moving black holes.
Dynamical Friction in Dark Matter
Black holes moving through ultralight dark matter experience dynamical friction, which affects their motion. This friction depends on the black hole's speed and spin, and it can be described using scattering amplitudes in black hole spacetimes .
Conclusion
Black holes can achieve remarkable velocities through various mechanisms, including recoil effects during binary mergers and natal kicks from supernovae. These velocities can range from a few hundred km/s to as high as 2500 km/s in extreme cases. The dynamics of moving black holes, including their interactions with surrounding media and dark matter, further illustrate the complex and fascinating nature of these cosmic objects.
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Supermassive recoil velocities for binary black-hole mergers with antialigned spins.
Supermassive recoil velocities of at least 2500 km/s are possible for equal-mass binaries with antialigned spins in binary black-hole mergers, potentially impacting models of black-hole formation and host galaxy structures.
Light speed rotating black holes: The special holes
The universe may be a growing and light speed rotating primordial black hole, with each galaxy containing a central fast growing and fast spinning black hole, and the present Hubble's constant may be a result of this growing and light speed rotating primordial black hole.
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