Kauffmann, Guinevere and Heckman, Timothy M. and Budavári, Tamás and Charlot, Stephane and Hoopes, Charles G. and Martin, D. Christopher and Seibert, Mark and Barlow, Tom A. and Bianchi, Luciana and Conrow, Tim and Donas, José and Forster, Karl and Friedman, Peter G. and Lee, Young-Wook and Madore, Barry F. and Milliard, Bruno and Morrissey, Patrick F. and Neff, Susan G. and Rich, R. Michael and Schiminovich, David and Small, Todd and Szalay, Alex S. and Wyder, Ted K. and Yi, Sukyoung K. (2007) Ongoing Formation of Bulges and Black Holes in the Local Universe: New Insights from GALEX. Astrophysical Journal Supplement Series, 173 (2). pp. 357-376. ISSN 0067-0049 http://resolver.caltech.edu/CaltechAUTHORS:20100205-135117202
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We analyze a volume-limited sample of massive bulge-dominated galaxies with data from both the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX) satellite. The galaxies have central velocity dispersions greater than 100 km s^(−1) and stellar surface mass densities that lie above the value where galaxies transition from actively star-forming to passive systems. The sample is limited to redshifts 0.03 < z < 0.07. At these distances, the SDSS spectra sample the light from the bulge-dominated central regions of the galaxies. The GALEX NUV data provide high sensitivity to low rates of global star formation in these systems. Our sample of bulge-dominated galaxies exhibits a much larger dispersion in NUV − r color than in optical g − r color. The dispersion increases for galaxies with smaller central velocity dispersions, and nearly all of the galaxies with bluer NUV − r colors are active galactic nuclei (AGNs). Both GALEX images and SDSS color profiles demonstrate that the excess UV light is nearly always associated with an extended disk. When comparing fiber-based estimates of stellar age to global ones, we find that galaxies with red outer regions almost never have a young bulge or a strong AGN. Galaxies with blue outer regions have bulges and black holes that span a wide range in age and accretion rate. Galaxies with young bulges and strongly accreting black holes almost always have blue outer disks. The black hole growth rate correlates much more strongly with the age of the stars in the bulge than in the disk. Our suggested scenario is one in which the source of gas that builds the bulge and black hole is a low-mass reservoir of cold gas in the disk. The presence of this gas is a necessary but not sufficient condition for bulge and black hole growth. Some mechanism must transport this gas inward in a time variable way. The disk gas itself is likely to be the result of the accretion of gas from an external source. As the gas in the disk is converted into stars, galaxies will turn red, but further inflow can bring them back into the blue NUV − r sequence.
|Additional Information:||© 2007 The American Astronomical Society. Received 2006 July 18; accepted 2006 September 13. GALEX (Galaxy Evolution Explorer) is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales (CNES) of France and the Korean Ministry of Science and Technology. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the US Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. The SDSS Web site is http://www.sdss.org. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, the Johns Hopkins University, the Korean Scientist Group, Los Alamos National Laboratory, the Max Planck Institute for Astronomy, the Max Planck Institute for Astrophysics, New Mexico State University, the University of Pittsburgh, the University of Portsmouth, Princeton University, the US Naval Observatory, and the University of Washington.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||galaxies : active; galaxies : bulges; galaxies : elliptical and lenticular, cD; galaxies : formation|
|Official Citation:||Ongoing Formation of Bulges and Black Holes in the Local Universe: New Insights from GALEX Guinevere Kauffmann, Timothy M. Heckman, Tamás Budavári, Stephane Charlot, Charles G. Hoopes, D. Christopher Martin, Mark Seibert, Tom A. Barlow, Luciana Bianchi, Tim Conrow, José Donas, Karl Forster, Peter G. Friedman, Young-Wook Lee, Barry F. Madore, Bruno Milliard, Patrick F. Morrissey, Susan G. Neff, R. Michael Rich, David Schiminovich, Todd Small, Alex S. Szalay, Ted K. Wyder, and Sukyoung K. Yi 2007 ApJS 173 357-376 doi: 10.1086/516647|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||10 Feb 2010 18:38|
|Last Modified:||04 Mar 2013 18:16|
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