($\leq$10%) changes in the rms noise and the inferred CO(3–2) luminosity. We use these re-imaged data only for the spectral comparison in Section \[fig:moments+spectra\]; the CO(3–2) source size and hence the bulk of our analysis in Section \[sec:discussion\] is based on the $uv$-plane analysis and hence is unaffected by the imaging procedure. We adopt @CR18 CO(3–2) luminosity and gas mass estimates for the remainder of this paper.

### ALMA 160-$\mu$m continuum

The rest-frame 160-$\mu$m continuum is detected in both sources at $>$10 $\sigma$-confidence (Figure \[fig:aless\_images\]). In both sources, the continuum emission shows only a single brightness peak at 0.15-arcsec resolution. In ALESS 49.1, the continuum emission is almost circularly symmetric, with a minor extension in the east-west direction. In ALESS 57.1, the continuum is noticeably extended in the east-west direction (axis ratio $\sim$2:1). The spatially-integrated 160-$\mu$m continuum flux-density for ALESS 49.1 and 57.1 is given in Table \[tab:targets+observed\]. The 160-$\mu$m flux-density is calculated from an aperture with a 1.0 arcsec diameter, centered on the 160-$\mu$m continuum surface brightness maximum. The aperture size was chosen based on the FIR continuum and \[\] sizes determined from the $uv$-plane fitting (Section \[subsec:uv-plane\] as we do not expect significant surface brightness contribution $\geq$0.5 arcsec 