Nicholas J. McConnell, Chung-Pei Ma
New kinematic data and modeling efforts in the past few years have substantially expanded and revised dynamical measurements of black hole masses (Mbh) at the centers of nearby galaxies. Here we compile an updated sample of 72 black holes and their host galaxies, and present revised scaling relations between Mbh and stellar velocity dispersion (sigma), V-band luminosity (L), and bulge stellar mass (Mbulge), for different galaxy subsamples. Our best-fitting power law relations for the full galaxy sample are log(Mbh) = 8.33 + 5.57*log(sigma/200 kms), log(Mbh) = 9.23 + 1.11*log(L/10^{11} Lsun), and log(Mbh) = 8.46 + 1.05*log(Mbulge/10^{11} Msun). When the early- and late-type galaxies are fit separately, we obtain nearly identical slopes of ~5 for the Mbh-sigma relation but significantly different intercepts. Within early-type galaxies, we find a significantly higher intercept for galaxies with central core profiles than for those with central power-law profiles. At fixed sigma, our fits predict Mbh to be about 2 times higher in early-type galaxies (versus late-type) and 2 times higher in core galaxies (versus power-law). Our Mbh-L and Mbh-Mbulge relations for early-type galaxies are similar to those from earlier compilations, and core and power-law galaxies yield similar L- and Mbulge-based predictions for Mbh. Our data set shows evidence for a systematic decrease in the scatter of Mbh from sigma ~200 km/s to sigma ~300 kms. Galaxies with L_V < 10^{10} Lsun or Mbulge < 10^{11} Msun exhibit more scatter in Mbh than galaxies at higher luminosities and bulge masses. Our measurements offer tentative support for theoretical predictions that galaxy merging results in a decreasing intrinsic scatter in Mbh with increasing galaxy mass.
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http://arxiv.org/abs/1211.2816
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