Jahnke, Knud and Bongiorno, Angela and Brusa, Marcella and Capak, Peter and Cappelluti, Nico and Cisternas, Mauricio and Civano, Francesca and Colbert, James and Comastri, Andrea and Elvis, Martin and Hasinger, Günther and Ilbert, Olivier and Impey, Chris and Inskip, Katherine and Koekemoer, Anton M. and Lilly, Simon and Maier, Christian and Merloni, Andrea and Riechers, Dominik and Salvato, Mara and Schinnerer, Eva and Scoville, Nick Z. and Silverman, John and Taniguchi, Yoshi and Trump, Jonathan R. and Yan, Lin (2009) Massive Galaxies in COSMOS: Evolution of Black Hole Versus Bulge Mass but not Versus Total Stellar Mass Over the Last 9 Gyr? Astrophysical Journal Letters, 706 (2). L215-L220. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100121-101835291
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We constrain the ratio of black hole (BH) mass to total stellar mass of type-1 active galactic nuclei (AGNs) in the COSMOS survey at 1 < z < 2. For 10 AGNs at mean redshift z ~ 1.4 with both Hubble Space Telescope (HST)/ACS and HST/NICMOS imaging data, we are able to compute the total stellar mass M_(*,total), based on rest-frame UV-to-optical host galaxy colors which constrain mass-to-light ratios. All objects have virial M_(BH) estimates available from the COSMOS Magellan/IMACS and zCOSMOS surveys. We find within errors zero difference between the M_(BH)-M_(*,total) relation at z ~ 1.4 and the M_(BH)-M_(*,bulge) relation in the local universe. Our interpretation is (1) if our objects were purely bulge-dominated, the M_(BH)-M_(*,bulge) relation has not evolved since z ~ 1.4. However, (2) since we have evidence for substantial disk components, the bulges of massive galaxies (M_(*,total) = 11.1 ± 0.3 or log M_(BH) ~ 8.3 ± 0.2) must have grown over the last 9 Gyr predominantly by redistribution of the disk into the bulge mass. Since all necessary stellar mass exists in galaxies at z = 1.4, no star formation or addition of external stellar material is required, but only a redistribution, e.g., induced by minor and major merging or through disk instabilities. Merging, in addition to redistributing mass in the galaxy, will add both BH and stellar/bulge mass, but does not change the overall final M_(BH)/M_(*,bulge) ratio. Since the overall cosmic stellar and BH mass buildup trace each other tightly over time, our scenario of bulge formation in massive galaxies is independent of any strong BH feedback and means that the mechanism coupling BH and bulge mass until the present is very indirect.
|Additional Information:||© 2009. The American Astronomical Society. All rights reserved. Received 2009 July 29; accepted 2009 October 27; published 2009 November 10. K.J. thanks E. F. Bell, N. Neumayer, C. Y. Peng, and A. van der Wel for very fruitful discussions, and the anonymous referee for helpful suggestions. K.J. is supported through the Emmy Noether Programme of the German Science Foundation (DFG). D.R. acknowledges support from NASA through a Hubble Fellowship. Facilities: ESO VLT (VIMOS), HST (ACS, NICMOS), Magellan (IMACS), XMM-Newton|
|Subject Keywords:||galaxies: active; galaxies: evolution; galaxies: fundamental parameters; galaxies: nuclei|
|Official Citation:||Massive Galaxies in COSMOS: Evolution of Black Hole Versus Bulge Mass but not Versus Total Stellar Mass Over the Last 9 Gyr? Knud Jahnke, Angela Bongiorno, Marcella Brusa, Peter Capak, Nico Cappelluti, Mauricio Cisternas, Francesca Civano, James Colbert, Andrea Comastri, Martin Elvis, Günther Hasinger, Olivier Ilbert, Chris Impey, Katherine Inskip, Anton M. Koekemoer, Simon Lilly, Christian Maier, Andrea Merloni, Dominik Riechers, Mara Salvato, Eva Schinnerer, Nick Z. Scoville, John Silverman, Yoshi Taniguchi, Jonathan R. Trump, and Lin Yan 2009 ApJ 706 L215-L220 doi: 10.1088/0004-637X/706/2/L215|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||25 Jan 2010 19:08|
|Last Modified:||26 Dec 2012 11:43|
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