Pump Cycles and Population Flow Networks in Astrophysical Masers: an Application to Class II Methanol Masers with Different Saturation Degrees
Abstract
Analytic and computational methods of analyzing maser pumping cycles are developed for masers occurring in astrophysical environments. Maser pump efficiencies are usually limited by the efficiency of the pumping cycles which contain the collisional and radiative transitions in the paths. The method of identification and analysis of the cycles and their efficiencies in molecules is developed in the context of population flow networks. This method is applied to the realistic cases of radiative pump models of the Class II methanol masers which are located in the vicinities of ultracompact H II regions. We found that many (much more than 100) pump cycles contribute to the single maser transition of CH3OH (not a few efficient cycles) even if the maser is saturated. A method of identification of 'bottleneck' transitions in pump cycles is also developed. When the saturation increases, degrees of participation of particular transitions in production of maser flow approach their upper limits. This constrains the maximal value of the maser flow.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1994
- DOI:
- 10.1086/174680
- Bibcode:
- 1994ApJ...433..719S
- Keywords:
-
- H Ii Regions;
- Interstellar Masers;
- Maser Pumping;
- Mathematical Models;
- Methyl Alcohol;
- Nonthermal Radiation;
- Optical Transition;
- Monte Carlo Method;
- Probability Theory;
- Astrophysics;
- ISM: MOLECULES;
- MASERS;
- RADIATION MECHANISMS: NONTHERMAL