Galaxies M87 (Messier87) is a giant elliptical galaxy, which recently made it on me- dia worldwide for the first direct photograph of its supermassive black hole (SMBH). M87 has a stellar mass M* = 2.4.10¹2 Mo and a radius of 32 Kpc; the mass of its SMBH is estimated to be 6 billion solar masses. In this problem we shall use fundamental scaling relations to explore the physics of M87. (a) Determine the velocity dispersion o of M87, in units of [km/s], using the Virial mass approximation. (b) With the velocity dispersion o obtained at point a), use the appropriate scaling relation in order to predict the mass of the M87 SMBH.

Galaxies M87 (Messier87) is a giant elliptical galaxy, which recently made it on me- dia worldwide for the first direct photograph of its supermassive black hole (SMBH). M87 has a stellar mass M* = 2.4.10¹2 Mo and a radius of 32 Kpc; the mass of its SMBH is estimated to be 6 billion solar masses. In this problem we shall use fundamental scaling relations to explore the physics of M87. (a) Determine the velocity dispersion o of M87, in units of [km/s], using the Virial mass approximation. (b) With the velocity dispersion o obtained at point a), use the appropriate scaling relation in order to predict the mass of the M87 SMBH.