428 research outputs found

    A Reanalysis of Small Scale Velocity Dispersion in the CfA1 Survey

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    The velocity dispersion of galaxies on scales of r∼1h−1r\sim1h^{-1} Mpc, σ12(r)\sigma_{12}(r), may be estimated from the anisotropy of the galaxy-galaxy correlation function in redshift space. We present a reanalysis of the CfA1 survey, correct an error in the original analysis of Davis and Peebles (1983), and find that σ12(r)\sigma_{12}(r) is extremely sensitive to the details of how corrections for infall into the Virgo cluster are applied. We conclude that a robust value of σ12\sigma_{12} cannot be obtained from this survey. We also discuss results from other redshift surveys, including the effect of removing clusters.Comment: 12 pages, uuencoded(latex file + 2 Postscript figures), uses aas macro

    The Co-evolution of Galaxies, Black Holes, and AGN in a Hierarchical Universe

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    The observational link between Supermassive Black Holes (SMBH) and galaxies at low redshift seems to be very tight, and statistically the global evolution of star formation activity and BH accretion activity also seem to trace each other closely. However, pinning down the co-evolution of galaxies and BH on an object-by-object basis remains elusive. I present results from new models for the joint evolution of galaxies, SMBH, and AGN, which may be able to help resolve some of the observational puzzles. A unique aspect of these models is our treatment of self-regulated BH growth based on hydrodynamic simulations of galaxy-galaxy mergers. Although these models do quite well at reproducing the observed evolution of galaxies, they do not reproduce the observed history of BH accretion, predicting too much early accretion and not enough at late times. I suggest two possible resolutions to this problem.Comment: to appear in "Panoramic Views of Galaxy Formation and Evolution", First Subaru International Conference, Hayama, Japan, December 200
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