Anonymousabout 20 hours ago
Astronomers led by Dr. Steve Prabu have used 18 years of radio imaging to make the first direct measurement of a black hole jet's power and speed by tracking how a companion star's wind bends the outflow from Cygnus X-1. The jet moves at roughly half the speed of light and carries about 10,000 solar luminosities of kinetic power, confirming — within factor-of-two uncertainties — the long-assumed 10% accretion-to-jet efficiency that underpins cosmological galaxy-formation simulations. Skeptics point to unresolved uncertainties in jet inclination, stellar wind modeling, and jet composition as pressure points on the precise numbers.