super massive black holes

[acsinnz]

Is it true that each galaxy has a super massive black hole SMBH at its centre around which all its stars rotate? If so, then is the size of that SMBH related to the total volume size of that galaxy or to the relative mass of that galaxy. Anyone know a reference to look up please??
CliveS

 

[MeteorWayne]

Is it true that each galaxy has a super massive black hole SMBH at its centre around which all its stars rotate? If so, then is the size of that SMBH related to the total volume size of that galaxy or to the relative mass of that galaxy. Anyone know a reference to look up please??
CliveS

Not all galaxies have a supermassive black hole, but it appears that most masssive galaxies do.

And the relationship appears to be betweem the mass of the black hole, and the mass of the galaxy.