A mass estimate of an intermediate-mass black hole in omega Centauri
  Context. The problem of the existence of intermediate-mass black holes
(IMBHs) at the centre of globular clusters is a hot and controversial topic in
current astrophysical research with important implications in stellar and
galaxy formation.
  Aims. In this paper, we aim at giving further support to the presence of an
IMBH in omega Centauri and at providing an independent estimate of its mass.
  Methods. We employed a self-consistent spherical model with anisotropic
velocity distribution. It consists in a generalisation of the King model by
including the Bahcall-Wolf distribution function in the IMBH vicinity.
  Results. By the parametric fitting of the model to recent HST/ACS data for
the surface brightness profile, we found an IMBH to cluster total mass ratio of
M_BH/M = 5.8(+0.9-1.2) x 10^(-3). It is also found that the model yields a fit
of the line-of-sight velocity dispersion profile that is better without mass
segregation than in the segregated case. This confirms the current thought of a
non-relaxed status for this peculiar cluster. The best fit model to the
kinematic data leads, moreover, to a cluster total mass estimate of M = (3.1
+/- 0.3) x 10^6 Msol, thus giving an IMBH mass in the range 13,000 < M_BH <
23,000 Msol (at 1-sigma confidence level). A slight degree of radial velocity
anisotropy in the outer region (r > 12') is required to match the outer surface
brightness profile.
