Constraint on the black-hole spin of M87 from the accretion-jet model

Understand

The millimeter bump, as found in high-resolution multi-waveband observations of M87, most possibly comes from the synchrotron emission of thermal electrons in advection dominated accretion flow(ADAF).

• It is possible to constrain the accretion rate near the horizon if both the nuclear millimeter emission and its polarization are produced by the hot plasma in the accretion flow.
• The jet power of M87 has been extensively explored, which is around $8_{\rm -3}^{+7}\times10^{42} {\rm erg/s}$ based on the analysis of the X-ray cavity.
• The black hole(BH) spin can be estimated if the jet power and the accretion rate near the horizon are known.