The parameters listed above are entered in the input file premap.inp. The reference opacity at 300 µm is defined with respect to the total mass (Marsh et al. 2015).

(a) The maps are Nyquist-sampled with pixels of size 1.25″, hence the synthetic resolution is 2.5″. noverlap ≥ 0.5 ncells is recommended by the PPMAP user manual. With ncells = 60 and noverlap = 40, all ALMA-IMF regions are contained either in a 3 × 3 or 5 × 5 mosaic. In some cases we increased noverlap to 50 in order to enhance the quality of the subfields seaming, thereby using 7 × 7 mosaics.

(b) The reference opacity κ₃₀₀ is defined by Eq. (6).

(c) The a priori dilution input parameter, “eta”, characterizes the degree to which the procedure is forced to represent the data with the least number of “points” (that is, with the least number of MBB components with distinct dust temperatures T_dust ). Values in the range 0.01 – 1 are recommended, but setting the input to “0” causes an internal PPMAP subroutine to adopt a default value, defined as η = N_prior/N_states, where N_prior is the maximum number of components that the data may constrain, and N_states = N_X × N_Y × N_T × N_β is the number of states that an “point” can occupy (see Sect. 3.1).

(d) Enables a PPMAP subroutine to subtract mean value from model and ground-based observed images during the SED fitting process.