Formation and evolution of massive black hole seeds at high redshift

I describe a simple analytical model to predict the amount of baryonic matter available in the center of dark matter halos at high redshift, to fuel the early formation and growth of the seeds of supermassive black holes. In this model black hole seed formation occurs in mini-halos with Tvir~104K before the Universe was significantly enriched by metals. If H2 formation is inhibited, we find that such halos would naturally form central mass concentrations of the order of 105M that we associate with the seed of supermassive black holes. Our model produces low-redshift black hole densities in good agreement with Soltan-type arguments, and predicts a flattening of the black hole density at redshift larger than z~6. We also predict a relative dearth of SMBH in dwarf galaxies at z = 0.