Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-30T20:16:19.018Z Has data issue: false hasContentIssue false
  • English
  • Français

A connection between bulge properties and the bimodality of galaxies

Published online by Cambridge University Press:  01 July 2007

Niv Drory  and
David B. Fisher
Niv Drory
Affiliation:
Max-Planck Institute for Extraterrestrial Physics, Giessenbachstr., Garching, Germany
David B. Fisher
Affiliation:
Department of Astronomy, The University of Texas at Austin, 1 University Station C1400, Austin, Texas 78712, U.S.A.
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The global colors and structure of galaxies have recently been shown to follow bimodal distributions. Galaxies separate into a “red sequence”, populated prototypically by early-type galaxies, and a “blue cloud”, whose typical objects are late-type disk galaxies. Intermediate-type (Sa-Sbc) galaxies populate both regions. It has been suggested that this bimodality reflects the two-component nature of disk-bulge galaxies. However, it has now been established that there are two types of bulges: “classical bulges” that are dynamically hot systems resembling (little) ellipticals, and “pseudobulges”, dynamically cold, flattened, disk-like structures that could not have formed via violent relaxation. Alas, given the different formation mechanisms of these bulges, the question is whether at types Sa-Sbc, where both bulge types are found, the red-blue dichotomy separates galaxies at some value of disk-to-bulge ratio, B/T, or, whether it separates galaxies of different bulge type, irrespective of their B/T. In this paper, we identify classical bulges and pseudobulges morphologically with HST images in a sample of nearby galaxies. Detailed surface photometry reveals that: (1) The red – blue dichotomy is a function of bulge type: at the same B/T, pseudobulges are in globally blue galaxies and classical bulges are in globally red galaxies. (2) Bulge type also predicts where the galaxy lies in other (bimodal) global structural parameters: global Sérsic index and central surface brightness. Hence, the red – blue dichotomy is not due to decreasing bulge prominence alone, and the bulge type of a galaxy carries significance for the galaxy's evolutionary history.

Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 3 , Symposium S245: Formation and Evolution of Galaxy Bulges , July 2007 , pp. 67 - 70
Copyright
Copyright © International Astronomical Union 2008

References

Adelman-McCarthy, J. K., et al. 2006, ApJS, 162, 38CrossRefGoogle Scholar
Baldry, I. K., Glazebrook, K., Brinkmann, J., Ivezić, Ž., Lupton, R. H., Nichol, R. C., & Szalay, A. S. 2004, ApJ, 600, 681CrossRefGoogle Scholar
Balogh, M. L., Baldry, I. K., Nichol, R., Miller, C., Bower, R., & Glazebrook, K. 2004, ApJL, 615, L101CrossRefGoogle Scholar
Carollo, C. M., Stiavelli, M., de Zeeuw, P. T., & Mack, J. 1997, AJ, 114, 2366CrossRefGoogle Scholar
de Jong, R. S. 1996, A&A, 313, 377Google Scholar
de Vaucouleurs, G., de Vaucouleurs, A., Corwin, H. G. Jr., Buta, R. J., Paturel, G., & Fouque, P. 1991, Third Reference Catalogue of Bright Galaxies (Volume 1-3, XII, 2069 pp. 7 figs. Springer-Verlag Berlin Heidelberg New York)Google Scholar
Driver, S. P., et al. 2006, MNRAS, 368, 414CrossRefGoogle Scholar
Drory, N. & Fisher, D. B. 2007, ApJ, 664, 640CrossRefGoogle Scholar
Fathi, K. & Peletier, R. F. 2003, A&A, 407, 61Google Scholar
Kent, S. M. 1985, ApJS, 59, 115CrossRefGoogle Scholar
Kormendy, J. 1993, in IAU Symp. 153: Galactic Bulges, 209CrossRefGoogle Scholar
Kormendy, J., Cornell, M. E., Block, D. L., Knapen, J. H., & Allard, E. L. 2006, ApJ, 642, 765CrossRefGoogle Scholar
Kormendy, J. & Fisher, D. B. 2005, in Revista Mexicana de Astronomia y Astrofisica Conference Series, ed. Torres-Peimbert, S. & MacAlpine, G., 101Google Scholar
Kormendy, J. & Kennicutt, R. C. Jr., 2004, ARAA, 42, 603CrossRefGoogle Scholar
Liske, J., Lemon, D. J., Driver, S. P., Cross, N. J. G., & Couch, W. J. 2003, MNRAS, 344, 307CrossRefGoogle Scholar
MacArthur, L. A., Courteau, S., Bell, E., & Holtzman, J. A. 2004, ApJS, 152, 175CrossRefGoogle Scholar
Moore, B., Katz, N., Lake, G., Dressler, A., & Oemler, A. Jr., 1996, Nature, 379, 613CrossRefGoogle Scholar
Peletier, R. F. & Balcells, M. 1996, AJ, 111, 2238CrossRefGoogle Scholar
Strateva, I., et al. 2001, AJ, 122, 1861CrossRefGoogle Scholar