Physics
Scientific paper
Dec 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008phdt........13s&link_type=abstract
Proquest Dissertations And Theses 2008. Section 0227, Part 0606 179 pages; [Ph.D. dissertation].United States -- Texas: The Uni
Physics
Supermassive, Black Holes, Quasars, Galaxies
Scientific paper
This dissertation addresses the co-evolutionary relationship between central supermassive black holes and host galaxies. This relationship is suggested by observed correlations between black hole mass and properties of the host galaxy bulge. We first discuss investigation of the relationship between black hole mass and host galaxy velocity dispersion for quasars in the Sloan Digital Sky Survey (SDSS). We derive the mass from the broad emission line width and continuum luminosity, and the dispersion from the width of narrow forbidden emission lines. For redshifts z < 0.5, our results agree with the locally- observed black hole mass - velocity dispersion relationship. For 0.5 < z < 1.2, the relationship appears to evolve with redshift in the sense that bulges are too small for their black holes. Part of this apparent trend can be attributed to observational biases, including a Malmquist bias involving the quasar luminosity. Accounting for these biases, we find approximately a factor of two evolution in the black hole mass - velocity dispersion relationship between the present and redshift z = 1. The second topic involves a search for the largest velocity dispersion galaxies in the SDSS. Black holes in quasars can have masses exceeding 5 billion solar masses, implying dispersions greater than 500 km/s by the local black hole mass - velocity dispersion relationship. We present high signal-to-noise HET observations for eight galaxies at redshift z < 0.3 from the SDSS showing large dispersions while appearing to be single galaxies in HST images. The maximum velocity dispersion we find is 444 km/s, suggesting either that quasar black hole masses are overestimated or that the black hole - bulge relationship changes at high black hole mass. The third topic involves work contributed to co-authored papers, including: (1) evidence for recoiling black holes in SDSS quasars, (2) the [O III] width - velocity dispersion relationship in active galactic nuclei (AGN), and (3) accretion disk temperatures and continuum colors in quasars. Lastly, we discuss research in progress, including: (1) possible physical influences on the width of narrow emission lines of SDSS AGN including the gravitational effect of the black hole, and (2) a search for binary AGN in the SDSS using double-peaked [O III] emission lines.
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