Table 5
Mean values and Kendall’s τ rank correlation coefficient (p-value given in parentheses).
| Kendall’s τ rank correlation coefficient | ||||||
|---|---|---|---|---|---|---|
| Line Ratio | 〈R〉 | 〈R〉equal | Radius | CO(2–1) | ΣTIR | |
| (1) | (2) | (3) | (4) | (5) | ||
| 12CO (2–0) |  |
 |
−0.20 (0.82) | −0.6 (0.14) | −0.6 (0.23) | |
| 12CO (3–2)/(2–1) |  |
 |
−0.80 (0.083) | 1.0 (0.003) | 1.0 (0.083) | |
| 13CO (2–0) |  |
 |
−0.80 (0.083) | −0.2 (0.7) | 1.0 (0.083) | |
| C18O (2–) |  |
 |
− | − | − | |
| fixed-J 1 → 0 | 13CO/12CO |  |
 |
−1.0 (0.017) | 0.6 (0.13) | 0.40 (0.48) |
| C18O/12CO |  |
 |
−0.80 (0.083) | 1.0 (0.017) | 0.67 (0.33) | |
| C18O/13CO |  |
 |
−0.80 (0.083) | 0.80 (0.083) | 0.67 (033) | |
| C17O/12CO | – | – | 1.0 (0.3) | – | −1.0 (0.33) | |
| C17O/13CO | – | – | 1.0 (0.3) | – | −1.0 (0.33) | |
| C17O/C18O | – | – | 1.0 (0.3) | – | −1.00(0.33) | |
| fixed-J 2 → 1 | 13CO/12CO |  |
 |
−1.0 (0.017) | 0.73 (0.056) | 1.0 (0.083) |
| C18O/12CO |  |
 |
– | – | – | |
| C18O/13CO |  |
 |
– | – | – | |
Notes. They are measured for the line ratios of stacked spectra as a function of galactocentric radius, CO (2–1) brightness temperature, and TIR surface brightness (see Figs. 6, 7, and 8). Only stacked points with S/N > 5 are considered. A dash indicates that only two or fewer significant measurements exist for the specific line ratio. (1) 〈R〉 indicates the average line ratio weighted by 12CO (2–1) brightness temperature (see Eq. (8)). The uncertainty for each line ratio is given by the weighted 16th and 84th percentiles. (2) The volume weighted median line ratio and 16th and 84th percentiles (since all pixel have the same size, this corresponds to weighing all points equally). (3) For the correlation coefficient computation, we only include stacked points at rgal < 5 kpc. (4) Only includes stacked points with WCO(2–1) > 2 K km s−1. (5) The correlation coefficient computation does not include any additional constraints.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.