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Register a new userA Relationship Between Nuclear Black Hole Mass and Galaxy Velocity Dispersion
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We describe a correlation between the mass M_BH of a galaxys central black hole and the luminosity-weighted line-of-sight velocity dispersion sigma_e within the half-light radius. The result is based on a sample of 26 galaxies, including 13 galaxies with new determinations of black hole masses from Hubble Space Telescope measurements of stellar kinematics. The best-fit correlation is M_BH = 1.2 (+-0.2) x 10^8 M_sun (sigma_e/200 km/s)^(3.75 (+-0.3))over almost three orders of magnitude in M_BH; the scatter in M_BH at fixed sigma_e is only 0.30 dex and most of this is due to observational errors. The M_BH-sigma_e relation is of interest not only for its strong predictive power but also because it implies that central black hole mass is constrained by and closely related to properties of the host galaxys bulge.
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The recent discovery of a correlation between nuclear black hole mass, M_bh, and the stellar velocity dispersion (Gebhardt et al. 2000, Ferrarese and Merritt 2000), in elliptical galaxies and spiral bulges, has raised the question whether such a relationship exists for AGN. Estimates of M_bh for many AGN, made using reverberation mapping techniques, allow exploration of the relationship between black hole mass, the host galaxy and the energetics of nuclear emission. However, since only a few AGN have both M_bh and velocity dispersion measurements, we use the [OIII] 5007 emission line widths on the assumption that for most AGN the forbidden line kinematics are dominated by virial motion in the host galaxy bulge. We find that a relation does exist between M_bh and [OIII] line width for AGN which is similar to the one found by Gebhardt et al. 2000, although with more scatter as expected if secondary influences on the gas kinematics are also present. Our conclusion is that both active and inactive galaxies follow the same relationship between black hole mass and bulge gravitational potential. We find no compelling evidence for systematic differences in the mass estimates from reverberation mapping and stellar dynamics. We also find that for radio quiet AGN the radio power and black hole mass are highly correlated linking emission on scales of kiloparsecs with the nuclear energy source.
Observations of nearby galaxies reveal a strong correlation between the mass of the central dark object M and the velocity dispersion sigma of the host galaxy, of the form log(M/M_sun) = a + b*log(sigma/sigma_0); however, published estimates of the slope b span a wide range (3.75 to 5.3). Merritt & Ferrarese have argued that low slopes (<4) arise because of neglect of random measurement errors in the dispersions and an incorrect choice for the dispersion of the Milky Way Galaxy. We show that these explanations account for at most a small part of the slope range. Instead, the range of slopes arises mostly because of systematic differences in the velocity dispersions used by different groups for the same galaxies. The origin of these differences remains unclear, but we suggest that one significant component of the difference results from Ferrarese & Merritts extrapolation of central velocity dispersions to r_e/8 (r_e is the effective radius) using an empirical formula. Another component may arise from dispersion-dependent systematic errors in the measurements. A new determination of the slope using 31 galaxies yields b=4.02 +/- 0.32, a=8.13 +/- 0.06, for sigma_0=200 km/s. The M-sigma relation has an intrinsic dispersion in log M that is no larger than 0.3 dex. In an Appendix, we present a simple model for the velocity-dispersion profile of the Galactic bulge.
We assess evolution in the black hole mass - stellar velocity dispersion relationship (M-sigma relationship) for quasars in the Sloan Digital Sky Survey Data Release 7 for the redshift range 0.1 < z < 1.2. We estimate the black hole mass using the photoionization method, with the broad Hbeta or Mg II emission line and the quasar continuum luminosity. For the stellar velocity dispersion, we use the narrow [O III] or [O II] emission line as a surrogate. This study is a follow-up to an earlier study in which we investigated evolution in the M-sigma relationship in quasars from Data Release 3. The greatly increased number of quasars in our new sample has allowed us to break our lower-redshift subsample into black hole mass bins and probe the M-sigma relationship for constant black hole mass. The M-sigma relationship for the highest-mass (log M > 9 solar masses) and lowest-mass (log M < 7.5 solar masses) black holes appears to evolve significantly, however most or all of this apparent evolution can be accounted for by various observational biases due to intrinsic scatter in the relationship and to uncertainties in observed quantities. The M-sigma relationship for black holes in the middle mass range (7.5 < log M < 9 solar masses) shows minimal change with redshift. The overall results suggest a limit of +/- 0.2 dex on any evolution in the M-sigma relationship for quasars out to z ~ 1 compared with the relationship observed in the local universe. Intrinsic scatter may also provide a plausible way to reconcile the wide range of results of several different studies of the black hole - galaxy relationships.
Supermassive Black Holes (BHs) residing in brightest cluster galaxies (BCGs) are overly massive when considering the local relationships between the BH mass and stellar bulge mass or velocity dispersion. Due to the location of these BHs within the cluster, large-scale cluster processes may aid the growth of BHs in BCGs. In this work, we study a sample of 71 galaxy clusters to explore the relationship between the BH mass, stellar bulge mass of the BCG, and the total gravitating mass of the host clusters. Due to difficulties in obtaining dynamically measured BH masses in distant galaxies, we use the Fundamental Plane relationship of BHs to infer their masses. We utilize X-ray observations taken by $Chandra$ to measure the temperature of the intra-cluster medium (ICM), which is a proxy for the total mass of the cluster. We analyze the $rm M_{BH}-kT$ and $rm M_{BH}-M_{Bulge}$ relationships and establish the best-fitting power laws:$log_{10}(M_{rm BH} /10^9 M_{odot})=-0.35+2.08 log_{10}(kT / 1 rm keV)$ and $log_{10}(rm M_{BH}/10^9M_{odot})= -1.09+ 1.92 log_{10}(M_{rm bulge}/10^{11}M_{odot})$. Both relations are comparable with that established earlier for a sample of brightest group/cluster galaxies with dynamically measured BH masses. Although both the $rm M_{BH}-kT$ and the $rm M_{BH}-M_{Bulge}$ relationships exhibit large intrinsic scatter, based on Monte Carlo simulations we conclude that dominant fraction of the scatter originates from the Fundamental Plane relationship. We split the sample into cool core and non-cool core resembling clusters, but do not find statistically significant differences in the $rm M_{BH}-kT$ relation. We speculate that the overly massive BHs in BCGs may be due to frequent mergers and cool gas inflows onto the cluster center.
Using a sample of more than 6000 quasars from the Sloan digital sky survey (SDSS) we compare the black-hole mass distributions of radio-loud and radio-quiet quasars. Based on the virial black-hole mass estimator the radio-loud quasars (RLQs) are found to harbour systematically more massive black holes than radio-quiet quasars (RQQs) with very high significance (>>99.99%), with mean black-hole masses of <log(M_{bh}/Msun)>=8.89pm0.02 and <log(M_{bh}/Msun)>=8.69pm0.01 for the RLQs and RQQs respectively. Crucially, the new RLQ and RQQ samples have indistinguishable distributions on the redshift-optical luminosity plane, excluding the possibility that either parameter is responsible for the observed black-hole mass difference. Moreover, this black-hole mass difference is shown to be in good agreement with the optical luminosity difference observed between RLQ and RQQ host galaxies at low redshift (i.e. Delta M_{host}=0.4-0.5 magnitudes). Within the SDSS samples, black-hole mass is strongly correlated with both radio luminosity and the radio-loudness $mathcal{R}$ parameter (>7 sigma significance), although the range in radio luminosity at a given black-hole mass is several orders of magnitude. It is therefore clear that the influence of additional physical parameters or evolution must also be invoked to explain the quasar radio-loudness dichotomy.
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