Constraining primordial black holes as fraction of dark matter through
  accretion disk luminosity
  In this paper, we consider the hypothesis that fractions of dark matter could
be constituted by primordial black holes (PBHs). To test this possibility, we
work out the observational properties of a static black hole embedded in the
dark matter envelope made of a PBH source. The corresponding modifications of
geometry due to such a physical system are investigated, with particular focus
on the accretion disk luminosity in spiral galaxies. The impact of the PBH
presence is analyzed through modification of the disk luminosity and kinematic
quantities. Thus, we discuss possible constraints on the PBH abundance in view
of the most recent theoretical bounds. The results of our study indicate that
suitable PBH masses are $M_\text{PBH}\in[10^6,10^{12}]M_\odot$ for PBH
fractions $f_\text{PBH}\in[10^{-3},1]$. In particular, a comparison with the
predictions of the exponential sphere density profile for dark matter suggests
that the best-matching configuration is achieved for $f_\text{PBH}=1$ and
$M_\text{PBH}=10^6 M_\odot$. Consequences with respect to the current knowledge
on primordial black hole physics are discussed.
