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Theory of Astronomical Masers

Published online by Cambridge University Press:  03 August 2017

Nikolaos D. Kylafis
Nikolaos D. Kylafis*
Affiliation:
University of Crete, Physics Department, P. O. Box 470, 714 09 Iraklion, Crete, GREECE

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The theory of astronomical masers is reviewed. As with laboratory masers, masing occurs when a transition between two energy levels of a molecule exhibits inverted populations. In order to present the basic concepts about masers, an idealized two-level system is used. The exact energy level structure is taken into account later on when the pumping of specific molecules is discussed. Unlike laboratory masers, where the radiation must be bounced between two mirrors to accumulate gain, the propagation of radiation in astronomical masers is a lot simpler. This is because astronomical masers are single-pass and broadband. Thus, the main theoretical effort has concentrated on inventing efficient mechanisms that produce population inversion. Specific pumping mechanisms for the three molecules (H2O, SiO, and OH) that exhibit strong masing are presented and their ability to explain the observations is discussed.

Type
Galactic
Information
Symposium - International Astronomical Union , Volume 129: The Impact of VLBI on Astrophysics and Geophysics , 1988 , pp. 223 - 230
Copyright
Copyright © Reidel 1988 

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