Hostname: page-component-cd9895bd7-p9bg8 Total loading time: 0 Render date: 2024-12-26T03:55:04.648Z Has data issue: false hasContentIssue false
  • English
  • Français

Dynamical Theory of Dense Groups of Galaxies

Published online by Cambridge University Press:  12 April 2016

Gary A. Mamon
Gary A. Mamon*
Affiliation:
DAEC Observatoire de Meudon Meudon, France

Extract

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.

It is well known that galaxies associate in groups and clusters. Perhaps 40% of all galaxies are found in groups of 4 to 20 galaxies (e.g., Tully 1987). Although most groups appear to be so loose that the galaxy interactions within them ought to be insignificant, the apparently densest groups, known as compact groups appear so dense when seen in projection onto the plane of the sky that their members often overlap. These groups thus appear as dense as the cores of rich clusters. The most popular catalog of compact groups, compiled by Hickson (1982), includes isolation among its selection critera. Therefore, in comparison with the cores of rich clusters, Hickson’s compact groups (hereafter, HCGs) appear to be the densest isolated regions in the Universe (in galaxies per unit volume), and thus provide in principle a clean laboratory for studying the competition of very strong gravitational interactions. The $64,000 question here is then: Are compact groups really bound systems as dense as they appear? If dense groups indeed exist, then one expects that each of the dynamical processes leading to the interaction of their member galaxies should be greatly enhanced. This leads us to the questions: How stable are dense groups? How do they form? And the related question, fascinating to any theorist: What dynamical processes predominate in dense groups of galaxies?. If HCGs are not bound dense systems, but instead ID chance alignments (Mamon 1986, 1987; Walke & Mamon 1989) or 3D transient cores (Rose 1979) within larger looser systems of galaxies, then the relevant question is: How frequent are chance configurations within loose groups? In this review, I will answer these last four questions after comparing in some detail the methods used and the results obtained in the different studies of dense groups, while in the accompanying contribution, I will attempt to reconcile the recent observations of galaxy interactions in HCGs with a negative answer to the first question.

Type
VIII. Classical Theory of Multiplets
Information
International Astronomical Union Colloquium , Volume 124: Paired and Interacting Galaxies , 1990 , pp. 609 - 618
Copyright
Copyright © NASA 1990

References

Aarseth, S.J., and Fall, S.M. 1980, Ap. J., 236 43.Google Scholar
Barnes, J. 1985, M.N.R.A.S., 215 517.Google Scholar
Barnes, J. 1988, Ap. J., 331 699.CrossRefGoogle Scholar
Barnes, J. 1989, Nature, 338, 123.Google Scholar
Carnevali, P., Cavaliere, A., and Santangelo, P. 1981, Ap. J., 249 449.Google Scholar
Cavaliere, A., Santangelo, P., Tarquini, G., and Vittorio, N. 1982, in Clustering in the Universe, ed. Gerbal, D. and Mazure, A. (Gif-sur-Yvette: Editions Frontières), p. 25.Google Scholar
Cooper, R.G., and Miller, R.H. 1981, Ap. J., 254 16.Google Scholar
Dekel, A., Lecar, M., and Shaham, J. 1980, Ap. J., 241 946.Google Scholar
Hickson, P. 1982, Ap. J., 255 382.Google Scholar
Ishizawa, T., Matsumoto, R., Tajima, T., Kageyama, H., and Sakai, H. 1983, P.A.S.J., 35 61.Google Scholar
Ishizawa, T. 1986, Ap. Sp. Sci., 119 221.Google Scholar
Jones, B.J.T., and Efstathiou, G. 1979, M.N.R.A.S., 189 27.Google Scholar
Malumuth, E.M., and Richstone, D.O. 1984, Ap. J., 276 413.CrossRefGoogle Scholar
Mamon, G.A. 1985, Ph.D. thesis, Princeton University.Google Scholar
Mamon, G.A. 1986, Ap. J., 307 426.Google Scholar
Mamon, G.A. 1987, Ap. J., 321 622.CrossRefGoogle Scholar
Merritt, D. 1983, Ap. J., 264 24.Google Scholar
Miller, G.E. 1983, Ap. J., 268 495.CrossRefGoogle Scholar
Navarro, J.F., Mosconi, M.B., and Lambas, D.G. 1987, M.N.R.A.S., 228 501.Google Scholar
Ostriker, J.P., and Hausman, M. 1977, Ap. J. (Letters), 176, L51.CrossRefGoogle Scholar
Richstone, D.O. 1976, Ap. J., 204 642.Google Scholar
Richstone, D.O., and Malumuth, E.M. 1983, Ap. J., 268 30.Google Scholar
Roos, N. 1981, Astr. Ap., 95 349.Google Scholar
Roos, N., and Aarseth, S.J. 1982, Astr. Ap., 114 41.Google Scholar
Roos, N., and Norman, C.A. 1979, Astr. Ap., 76 75.Google Scholar
Rose, J.A. 1979, Ap. J., 231 10.CrossRefGoogle Scholar
Saarinen, S., and Valtonen, M.J. 1985, Astr. Ap., 153 130.Google Scholar
Schneider, D., and Gunn, J.E. 1982, Ap. J., 263 14.Google Scholar
Tully, R.B. 1987, Ap. J., 321 280.Google Scholar
Walke, D.G., and Mamon, G.A. 1989, Astr. Ap., 295 291.Google Scholar