Browsing by Subject "quasars: supermassive black holes"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Hunting for Supermassive Black Holes in Nearby Galaxies With the Hobby-Eberly Telescope(2015-05) van den Bosch, Remco C. E.; Gebhardt, Karl; Gultekin, Kayhan; Yildirim, Akin; Walsh, Jonelle L.; Gebhardt, Karl; Walsh, Jonelle L.We have conducted an optical long-slit spectroscopic survey of 1022 galaxies using the 10 m Hobby-Eberly Telescope (HET) at McDonald Observatory. The main goal of the HET Massive Galaxy Survey (HETMGS) is to find nearby galaxies that are suitable for black hole mass measurements. In order to measure accurately the black hole mass, one should kinematically resolve the region where the black hole dominates the gravitational potential. For most galaxies, this region is much less than an arcsecond. Thus, black hole masses are best measured in nearby galaxies with telescopes that obtain high spatial resolution. The HETMGS focuses on those galaxies predicted to have the largest sphere-of-influence, based on published stellar velocity dispersions or the galaxy fundamental plane. To ensure coverage over galaxy types, the survey targets those galaxies across a face-on projection of the fundamental plane. We present the sample selection and resulting data products from the long-slit observations, including central stellar kinematics and emission line ratios. The full data set, including spectra and resolved kinematics, is available online. Additionally, we show that the current crop of black hole masses are highly biased toward dense galaxies and that especially large disks and low dispersion galaxies are under-represented. This survey provides the necessary groundwork for future systematic black hole mass measurement campaigns.Item Refining The M-Bh-V-C Scaling Relation With H I Rotation Curves Of Water Megamaser Galaxies(2013-11) Sun, Ai-Lei; Greene, Jenny E.; Impellizzeri, C. M. Violette; Kuo, Cheng-Yu; Braatz, James A.; Tuttle, Sarah; Tuttle, SarahBlack-hole-galaxy scaling relations provide information about the coevolution of supermassive black holes and their host galaxies. We compare the black-hole mass-circular-velocity (M-BH-V-c) relation with the black-holemass-bulge-stellar-velocity-dispersion (M-BH-sigma(*)) relation to see whether the scaling relations can passively emerge from a large number of mergers or require a physical mechanism, such as feedback from an active nucleus. We present Very Large Array HI observations of five galaxies, including three water megamaser galaxies, to measure the circular velocity. Using 22 galaxies with dynamical M-BH measurements and V-c measurements extending to large radius, our best-fit M-BH-V-c relation, logMBH = alpha +beta log(V-c/200 km s(-1)), yields a = 7.43+0.13 -0.13, beta = 3.68(-1.20)(+1.23), and an intrinsic scatter is an element of(int) = 0.51(-0.09)(+0.11). The intrinsic scatter may well be higher than 0.51, as we take great care to ascribe conservatively large observational errors. We find comparable scatter in the M-BH-sigma(*) relations, is an element of(int) = 0.48(-0.08)(+0.10), while pure merging scenarios would likely result in a tighter scaling with the dark halo (as traced by V-c) properties rather than the baryonic (sigma(*)) properties. Instead, feedback from the active nucleus may act on bulge scales to tighten the M-BH-sigma(*) relation with respect to the M-BH-V-c relation, as observed.