Origin of quasar progenitors from the collapse of low-spin cosmological perturbations

Abstract

We show that seeds for quasar black holes could have originated from the initial cosmological collapse of overdense regions with unusually small rotation. The gas in these rare regions collapses into a compact disk that shrinks on a short viscous timescale. Using an analytical model, we calculate the low-spin tail of the probability distribution of angular momenta for objects that collapse out of a Gaussian random field of initial density perturbations. The population of low-spin systems is significant for any viable power spectrum of primordial density perturbations. Most objects form just above the cosmological Jeans mass ~10^5^ M_sun_ at high redshifts z ~> 10. In the standard cold dark matter cosmology, the comoving density of 10^6-7^ M_sun_ objects with viscous evolution times shorter than ~10^6-7^ years is ~10^-3^(h/0.5)^3^ Mpc^-3^, comparable to the local density of bright galaxies. The seed black holes tend to reside within larger mass systems that collapse later and supply the gas needed for the bright quasar activity.