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Boxy/peanut and discy bulges: formation, evolution and properties

Published online by Cambridge University Press:  01 July 2007

E. Athanassoula
E. Athanassoula*
Affiliation:
Laboratoire d'Astrophysique de Marseille, Observatoire Astronomique de Marseille Provence, 2 place Le Verrier, 13248 Marseille cedex 04, France
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Abstract

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The class ‘bulges’ contains objects with very different formation and evolution paths and very different properties. I review two types of ‘bulges’, the boxy/peanut bulges (B/Ps) and the discy bulges. The former are parts of bars seen edge-on, have their origin in vertical instabilities of the disc and are somewhat shorter in extent than bars. Their stellar population is similar to that of the inner part of the disc from which they formed. Discy bulges have a disc-like outline, i.e., seen face-on they are circular or oval and seen edge-on they are thin. Their extent is of the order of 5 times smaller than that of the boxy/peanut bulges. They form from the inflow of mainly gaseous material to the centre of the galaxy and from subsequent star formation. They thus contain a lot of young stars and gas. Bulges of different types often coexist in the same galaxy. I review the main known results on these two types of bulges and present new simulation results.

B/Ps form about 1Gyr after the bar, via a vertical buckling. At that time the bar strength decreases, its inner part becomes thicker – forming the peanut or boxy shape – and the ratio increases. A second buckling episode is seen in simulations with strong bars, also accompanied by a thickening of the peanut and a weakening of the bar. The properties of the B/Ps correlate strongly with those of the bar: stronger bars have stronger peanuts, a more flat-topped vertical density distribution and have experienced more bucklings.

I also present simulations of disc galaxy formation, which include the formation of a discy bulge. Decomposition of their radial density profile into an exponential disc and a Sérsic bulge gives realistic values for the disc and bulge scale-lengths and mass ratios, and a Sérsic shape index of the order of 1.

It is thus clear that classical bulges, B/P bulges and discy bulges are three distinct classes of objects and that lumping them together can lead to confusion. To avoid this, the two latter could be called B/P features and inner discs, respectively.

Keywords

galaxies: bulgesgalaxies: evolutiongalaxies: formationgalaxies: kinematics and dynamicsstellar dynamicsmethods: N-body simulations
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 3 , Symposium S245: Formation and Evolution of Galaxy Bulges , July 2007 , pp. 93 - 102
Copyright
Copyright © International Astronomical Union 2008

References

Araki, S. 1985 PhD thesis, MITGoogle Scholar
Aronica, G., Athanassoula, E., Bureau, M., Bosma, A., Dettmar, R.-J., Vergani, D., & Pohlen, M. 2003, Ap&SS, 284, 753Google Scholar
Athanassoula, E. 1992, MNRAS, 259, 345CrossRefGoogle Scholar
Athanassoula, E. 2002, ApJL, 569, 83 (A02)CrossRefGoogle Scholar
Athanassoula, E. 2003, MNRAS, 341, 1179 (A03)CrossRefGoogle Scholar
Athanassoula, E. 2005a, MNRAS, 358, 1477 (A05)CrossRefGoogle Scholar
Athanassoula, E. 2005b, in Planetary Nebulae as Astronomical Tools, eds. Szczerba, R., Stasińska, G., & Górny, S. K., AIP Conf. Proc. 804, Melville, New York, 333Google Scholar
Athanassoula, E., Beaton, R. L. 2006, MNRAS, 370, 1499CrossRefGoogle Scholar
Athanassoula, E. & Bureau, M. 1999, ApJ, 522, 699CrossRefGoogle Scholar
Athanassoula, E., Misiriotis, A. 2002, MNRAS, 330, 35 (AM02)CrossRefGoogle Scholar
Athanassoula, E., Martinez-Valpuesta, 2007, in Pathways through an eclectic Universe, eds. Knapen, J. H., Mahoney, T. J., and Vazdekis, A., ASP Conf. Ser., 2007, in press and astro-ph/0710.1518Google Scholar
Binney, J. 1978, MNRAS, 183, 501CrossRefGoogle Scholar
Binney, J. 1981, MNRAS, 196, 455CrossRefGoogle Scholar
Binney, J. 2005, MNRAS, 363, 937CrossRefGoogle Scholar
Bureau, M., Aronica, G., Athanassoula, E., Dettmar, R.-J., Bosma, A., & Freeman, K. C. 2006, MNRAS, 370, 753Google Scholar
Bureau, M. & Athanassoula, E. 2005, ApJ, 626, 159CrossRefGoogle Scholar
Bureau, M. & Freeman, K. C. 1999, AJ, 118, 126CrossRefGoogle Scholar
Chung, A. & Bureau, M. 2004, AJ, 127, 3192CrossRefGoogle Scholar
Combes, F. & Sanders, R. H. 1981, A&A, 96, 164Google Scholar
Combes, F., Debbasch, F., Friedli, D., & Pfenniger, D. 1990, A&A, 233, 82Google Scholar
Debattista, V. P., Carollo, M., Mayer, L., & Moore, B. 2004, ApJ, 604, L93CrossRefGoogle Scholar
Debattista, V. P., Carollo, M., Mayer, L.Moore, B., Wadsley, J., & Quinn, T. 2006, ApJ, 645, 209CrossRefGoogle Scholar
Friedli, D., & Benz, W. 1993, A&A, 268, 65Google Scholar
Heller, C. H. & Shlosman, I. 1994, ApJ, 424, 84CrossRefGoogle Scholar
Heller, C.H., Shlosman, I. & Athanassoula, E. 2007a, ApJ, 657, L65CrossRefGoogle Scholar
Heller, C. H., Shlosman, I., & Athanassoula, E. 2007b, ApJ, 671, 226CrossRefGoogle Scholar
Kormendy, J. 1993, in Galactic Bulges, eds. Dejonghe, H. and Habing, H. J., Kluwer Academic Publ., IAU Symposium 153, 209CrossRefGoogle Scholar
Kormendy, J., & Kennicutt, R. C. 2004, ARA&A, 42, 603 (KK04)Google Scholar
Kuijken, K. & Merrifield, M. R. 1995, ApJ, 443, L13CrossRefGoogle Scholar
Lütticke, R., Dettmar, R.-J. & Pohlen, M. 2000, A&A, 362, 435Google Scholar
Martinez-Valpuesta, I. & Shlosman, I. 2004, ApJ, 613, 29Google Scholar
Martinez-Valpuesta, I., Shlosman, I., & Heller, C. 2006, ApJ, 637, 214CrossRefGoogle Scholar
Merrifield, M. R. & Kuijken, K. 1999, A&A, 345, L47Google Scholar
Merritt, D. & Sellwood, J. A. 1994, ApJ, 425, 551CrossRefGoogle Scholar
O'Neill, J. K. & Dubinski, J. 2003, MNRAS, 346, 251CrossRefGoogle Scholar
Patsis, P., Skokos, Ch., Athanassoula, E. 2002, MNRAS, 337, 578CrossRefGoogle Scholar
Pfenniger, D. 1984, A&A, 134, 373Google Scholar
Raha, N., Sellwood, J. A., James, R. A., & Kahn, F. D. 1991, Nature, 352, 411CrossRefGoogle Scholar
Sérsic, J. 1968, Atlas de Galaxias Australes, Obs. Astron. CordobaGoogle Scholar
Skokos, H., Patsis, P. & Athanassoula, E. 2002, MNRAS, 333, 847CrossRefGoogle Scholar
Sotnikova, N. Ya. & Rodionov, S. A. 2003, AstL, 29, 321Google Scholar
Toomre, A. 1966, Geophys. Fluid Dyn., N66-46, 111Google Scholar
Valenzuela, O., Klypin, 2003, MNRAS, 345, 406Google Scholar
Wada, K. & Habe, A. 1995, MNRAS, 277, 433Google Scholar