Mon. Not. R. Astron. Soc., 436, 2708-2721 (2013/December-2)
The strong environmental dependence of black hole scaling relations.
Abstract (from CDS):
We investigate how the scaling relations between central black hole mass 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-neighbour 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 Mø-σ relation of central galaxies is significantly steeper (β = 6.38±0.49) than that of satellite galaxies (β = 4.91±0.49), but has a similar intercept. This behaviour remains even after restricting to a sample of only early-type galaxies or after removing the eight brightest cluster galaxies. The Mø-σ 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 in the current Mø-σ relation are representative progenitors of the satellite population, the observations imply that a σ = 120km/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.