Observational Evidence for a Correlation Between Jet Power and Black Hole Spin

TL;DR

This study provides observational evidence linking black hole spin to jet power, supporting the theory that jets are powered by black hole spin energy and validating the continuum-fitting method for measuring spin.

Contribution

First direct evidence showing a correlation between black hole spin and jet power, suggesting jets are powered by black hole spin energy and validating spin measurement techniques.

Findings

Radio flux correlates with black hole spin parameter a*

Jet power scales with the square of a* or horizon angular velocity

Correlation can estimate black hole spins from radio observations

Abstract

We show that the 5-GHz radio flux of transient ballistic jets in black hole binaries correlates with the dimensionless black hole spin parameter a* estimated via the continuum-fitting method. The data suggest that jet power scales either as the square of a* or the square of the angular velocity of the horizon. This is the first direct evidence that jets may be powered by black hole spin energy. The observed correlation validates the continuum-fitting method of measuring spin. In addition, for those black holes that have well-sampled radio observations of ballistic jets, the correlation may be used to obtain rough estimates of their spins.