Classification and statistical properties of H2O masers
The revised version of the Arcetri H2O maser Atlas (AA2) and the IRAS Point Source Catalog were used to associate each maser to one IRAS source. For 442 masers out of a total of 505 (87.5%) an association was established. However, only ≈3% occur in regions where no FIR emission can be found.
Based on this association an unbiased classification scheme was developed that uses all IRAS colours. A colour combination was derived which best characterizes the sources already identified as HII or STAR. This combination was then applied to the whole sample resulting in 262 HII and 229 STAR.
The following properties of each class were then studied: 1) the distribution of maser and far infrared luminosities, 2) the variability of the H2O maser emission, 3) the correlation between maser and far infrared luminosities, 4) the detectability of high velocity features in the spectrum and 5) the galactic distribution and luminosity function of the H2O masers of HII class.
KeywordsLinear Discriminant Analysis Luminosity Function Maser Emission Colour Combination IRAS Source
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