M84
M84 is a lenticular galaxy
(class S0) located in the dense central region of the Virgo Cluster,
about 18 Mpc away.
The black hole picture is supported by previously known information about this galaxy:
its nucleus is active
and emits jets of particles that are very strong radio sources. The observed radial velocities near the center suggest a
mass of about 300 million solar masses for the black hole.