The strong environmental dependence of black hole scaling relations
  We investigate how the scaling relations between central black hole mass
(Mbh) and host galaxy properties (velocity dispersion, bulge stellar mass and
bulge luminosity) depend on the large scale environment. For each of a sample
of 69 galaxies with dynamical black hole measurements we compile four
environmental measures (nearest neighbor distance, fixed aperture number
density, total halo mass, and central/satellite). We find that central and
satellite galaxies follow distinctly separate scalings in each of the three
relations we have examined. The Mbh - sigma relation of central galaxies is
significantly steeper (6.38 +/- 0.49) than that of satellite galaxies (4.91 +/-
0.49), but has a similar intercept. This behavior remains even after
restricting to a sample of only early type galaxies or after removing the 8
brightest cluster galaxies. The Mbh - sigma relation shows more modest
differences when splitting the sample based on the other environmental
indicators, suggesting that they are driven by the underlying satellite/central
fractions. Separate relations for centrals and satellites are also seen in the
power law scaling between black hole mass and bulge stellar mass or bulge
luminosity. We suggest that gas rich, low mass galaxies undergo a period of
rapid black hole growth in the process of becoming satellites. If central
galaxies on the current Mbh - sigma relation are representative progenitors of
the satellite population, the observations imply that a sigma = 120 km/s galaxy
must nearly triple its central black hole mass. The elevated black hole masses
of massive central galaxies are then a natural consequence of the accretion of
satellites.
