The Mass Function of Active Black Holes in the Local Universe

Understand

We present the first measurement of the black hole (BH) mass function for broad-line active galaxies in the local Universe.

• Using the ~9000 broad-line active galaxies from the Fourth Data Release of the Sloan Digital Sky Survey, we construct a broad-line luminosity function that agrees very well with the local soft X-ray luminosity function.
• Using standard virial relations, we then convert observed broad-line luminosities and widths into BH masses.
• A mass function constructed in this way has the unique capability to probe the mass region <10^6 M_sun, which, while insignificant in terms of total BH mass density, nevertheless may place important constraints on the mass distribution of seed BHs in the early Universe.