Astronomy Colloquium

An astrophysical black hole is fully described with only two parameters, its mass and its spin. This simplicity makes the black hole a perfect laboratory for exploring both the physics of accretion flows and the mechanisms by which relativistic jets are ejected. Using a combination of numerical simulations and observational data, our group has explored the properties of accretion disks around black holes, focusing in particular on the regions of the disk near and inside the innermost stable circular orbit. These studies have enabled us to measure the spin parameters of ten stellar-mass black holes. We find an intriguing correlation between the radio power of relativistic jets and the black hole spin parameter. This is the first direct evidence that jets may be powered by black hole spin energy.