Source Selection

- Information about source selection

The Hi-GAL sources have been selected from the catalog of Elia et al. (2017), which contains Hi-GAL sources lying in the area observed by both PACS and SPIRE, and provided with a SED (between 160 and 500 µm) eligible for grey-body fit, namely:
- complete (at least three consecutive fluxes out of four);
- concave downward and not increasing between 350 and 500 µm.
The flux at 70 µm is not involved in the fit. However, this flux is involved in the calculation of the bolometric luminosity, together with fluxes of possible MSX-Band-E, WISE-Band-4, MIPSGAL, ATLASGAL, and BGPS counterparts. Furthermore, its absence/presence is used as a switch to classify a source as starless/protostellar, respectively.

The constraints imposed on the positional and physical properties of such sources to select the ALMAGAL targets are the following:

• The source declination must be lower than -0.8°.
• The source must be provided with a heliocentric distance estimate (from Russeil et al. 2011), and this distance must be shorter than 7.5 kpc.
• The Galactic longitude must not be in the range -10.2° < l < 14°, within which the aforementioned distance estimates are considered poorly reliable.
• The source mass must be larger than 500 solar masses.
• The flux at 160 µm must be larger than 3 Jy.
• For starless sources only: the flux at 500 µm must be larger than 10 Jy, the source surface density must be larger than 0.8 g cm^-2, and the grey-body fit temperature must be larger than 7 K.
• Downstream of the automatic source selection described above, a visual inspection was performed to rule out possible unreliable candidates affected by residual issues on photometry and/or band merging (mainly due to occurrence of multiplicity in some bands).

- Locations and physical property statistics of selected sources