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X-ray Observations of Poor Groups

Published online by Cambridge University Press:  12 April 2016

John S. Mulchaey
John S. Mulchaey*
Affiliation:
The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA91101

Abstract

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X-ray observations of groups have provided considerable new insight into these cosmologically important systems. Recent ROSAT surveys of loose and compact groups suggest that ≃ 50% of all nearby groups contain a hot intragroup medium, including many spiral-rich groups. However, spiral-only groups tend not to be X-ray detected. Spectroscopic studies of X-ray groups indicate that these systems contain a large number of faint galaxies. The existence of a large population of faint galaxies, combined with the extended X-ray halos, is consistent with X-ray detected groups being real, bound systems. The nature of non-X-ray detected groups, which do not contain an extensive faint galaxy population, is still unclear.

ROSAT observations have also revealed the existence of individual elliptical galaxies with X-ray properties and total masses similar to those of X-ray groups. These objects may be the merger remnants of X-ray groups or ‘failed groups’ (i.e. overdensities that formed only a single galaxy). The number density of these objects suggests they make a non-negligible contribution to the mass density of the universe.

Type
Part 2. Properties of Small Groups
Information
International Astronomical Union Colloquium , Volume 174: Small Galaxy Groups , 2000 , pp. 174 - 181
Copyright
Copyright © Astronomical Society of the Pacific 2000

References

Helsdon, S.F., & Ponman, T.J. 1999, MNRAS, in press.Google Scholar
Henry, J.P., Gioia, I.M., Huchra, J.P., Burg, R., & McLean, B. 1995, ApJ, 449, 422 CrossRefGoogle Scholar
Hernquist, L., Katz, N. & Weinberg, D. 1995, ApJ, 442, 57 CrossRefGoogle Scholar
Hickson, P. 1982, ApJ, 255, 382 CrossRefGoogle Scholar
Mulchaey, J.S., Davis, D.S., Mushotzky, R.F., & Burstein, D. 1996, ApJ, 456, 80 CrossRefGoogle Scholar
Mulchaey, J.S., Zabludoff, A.I., 1998, ApJ, 496, 73 CrossRefGoogle Scholar
Mulchaey, J.S., Zabludoff, A.I., 1999, ApJ, 514, 133 Google Scholar
Pietsch, W., Trinchieri, G., Arp, H., Sulentic, J.W., 1997, AA, 322, 89 Google Scholar
Pildis, R.A., Bregman, J.N., Evrard, A.E., 1995, ApJ, 443, 514 CrossRefGoogle Scholar
Ponman, T.J., Allan, D.J., Jones, L.R., Merrifield, M., McHardy, I.M., 1994, Nature, 369, 462 CrossRefGoogle Scholar
Ponman, T.J., Bertram, D., 1993, Nature, 363, 51 Google Scholar
Ponman, T.J., Bourner, P.D.J., Ebeling, H., Böhringer, H., 1996, MNRAS, 283, 690 Google Scholar
Ribeiro, A.L.B., de Carvalho, R.R., Coziol, R., Capelato, H.V., & Zepf, S.E., 1996, ApJ, 463, 5 Google Scholar
Shectman, S.A., Landy, S.D., Oemler, A., Tucker, D.L., Lin, H., Kirshner, R.R., Schechter, P.L. 1996, ApJ, 470, 172 Google Scholar
van den Bergh, S. 1992, AA, 264, 75 Google Scholar
Vikhlinin, A., McNamara, B.R., Hornstruo, A., Quintana, H., Forman, W., Jones, C., & Way, M. 1999, ApJ, 520, L1 Google Scholar
Zabludoff, A.I., Mulchaey, J.S., 1998, ApJ, 496, 39 Google Scholar
Zaritsky, D. 1994, in The Local Group: Comparative and Global Properties, eds.Layden, A., Smith, R.C., and Storm, J., ESO Conference and Workshop Proceedings No. 51, p.187 Google Scholar