Table 2
Derived H2O column densities and abundances, column density ratios, and covering factors of the continua.
| Source | C a | N H2O b | χ H2O c | OH/H2Od | HCN/H2Od | HCN/NH3d | fC(H2O)e | fC(OH)e | fC(HCN, NH3)e |
| (cm-2) | |||||||||
|
|
|||||||||
| NGC 4418 | C core | (2−6) × 1018 | (0.5−1.5) × 10-5 | 0.3−0.6 | 0.1−0.3 | 2−4 | 0.85 | 1 | 0.7 |
| C warm | ~5 × 1016 | (0.5−2.5) × 10-7 | ~0.4 | 1 | 1 | ||||
| C extended | ~0.2 × 1016 | ~2 × 10-8 | 5−10 | 0.45 | 0.45 | ||||
| Arp 220 | C west | (0.8−6) × 1018 | (0.2−1.5) × 10-5 | 0.4−1.0 | 0.1−0.4 | 3−5 | 0.7−1 | 0.7−1 | 0.7−1 |
| C east | 3 × 1017 | 0.8 × 10-6 | ~1 | 0.4 | 0.4 | ||||
| C extended | 3 × 1016 | 4 × 10-8 | ~3 | 1 | 1 | ||||
| C halo | (5−10) × 1015 | 5 × 10-8 | ~10 | 0.7 | 1 | ||||
Notes.
Component (see Table 1). In Arp 220, Chalo is an absorbing, widespread component in front of the nuclear region.
Column densities per unit of dust opacity at 50 μm, τ50, for Ccore and Cwarm in NGC 4418, and for Cwest and Ceast in Arp 220, with an estimated column of H nuclei per τ50 of 4 × 1023 cm-2. For the Cextended component in both sources, mixed values (i.e., dust and molecules are coexistent throughout the source; see text for details).
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