Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-26T20:32:33.396Z Has data issue: false hasContentIssue false
  • English
  • Français

Pumping of H2O Megamasers

Published online by Cambridge University Press:  14 August 2015

Moshe Elitzur
Moshe Elitzur*
Affiliation:
Physics & Astronomy Department University of KentuckyLexington, KY 40506-0055USA

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.

Strong H2O maser emission is detected from active galactic nuclei (AGN) as well as Galactic objects such as star-forming regions and late-type stars. In spite of the widely different luminosities of the different masers, a common pump mechanism seems adequate: neutral collisions at densities of ˜ 108-1010 cm-3 and temperatures of ˜ 250-500 K. The different properties of the various masers can be attributed to geometry. Although disk rotation controls the AGN maser geometry it does not directly determine the dimensions. X-ray radiation and spiral shocks have been suggested as the heating sources of H2O megamasers. Both are capable of explaining the observations, and the radiative scenario seems best understood in terms of chance alignment of standard broad-line-region clouds. It is not yet clear whether these different proposals produce distinct maser signatures.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 11 , Issue 2: Highlights of Astronomy. As presented at the XXIIIrd General Assembly of the IAU (Part B), 1997 , 1998 , pp. 960 - 963
Copyright
Copyright © Kluwer 1998

References

Braatz, J. A., Wilson, A. S., & Henkel, C. 1997, ApJS, 110, 321 Google Scholar
Elitzur, M., Hollenbach, D. J., & McKee, C. F. 1989, ApJ, 346, 983 CrossRefGoogle Scholar
Gwinn, C.R. 1994, ApJ 429, 241 CrossRefGoogle Scholar
Hagiwara, Y., Kohno, K., Kawabe, R., & Nakai, N. 1997, PASJ, 49, 171 CrossRefGoogle Scholar
Herrnstein, J. R., et al. 1997, in ASP Conf. Ser., The Physics of LINERS in View of Recent Observations, ed. Eracleous, M., Koratkar, A. P., Ho, L. C., & Leitherer, C. (San Francisco: ASP), in pressGoogle Scholar
Kartje, J. F., & Königl, , & Elitzur, M. 1997, ApJ (submitted)Google Scholar
Liljeström, T. 1993, in Astrophysical Masers, eds. Clegg, AW. & Nedoluha, G.E. (Springer-Verlag), p. 291 CrossRefGoogle Scholar
Maoz, E., 1997, these proceedingsGoogle Scholar
Maoz, E., & McKee, C. F. 1997, ApJ, in pressGoogle Scholar
Miyoshi, M., et al. 1995, Nature, 373, 127 Google Scholar
Neufeld, D. A., Maloney, P. R., & Conger, S. 1994, ApJ, 436, L127 Google Scholar
Watson, W. D., & Wallin, B. K. 1994, ApJ, 432, L35 CrossRefGoogle Scholar