Characterization of Two 2mm-detected Optically-Obscured Dusty
  Star-Forming Galaxies
  The 2mm Mapping Obscuration to Reionization with ALMA (MORA) Survey was
designed to detect high redshift ($z\gtrsim4$), massive, dusty star-forming
galaxies (DSFGs). Here we present two, likely high redshift sources, identified
in the survey whose physical characteristics are consistent with a class of
optical/near-infrared (OIR) invisible DSFGs found elsewhere in the literature.
We first perform a rigorous analysis of all available photometric data to fit
spectral energy distributions and estimate redshifts before deriving physical
properties based on our findings. Our results suggest the two galaxies, called
MORA-5 and MORA-9, represent two extremes of the "OIR-dark" class of DSFGs.
MORA-5 ($z_{\rm phot}=4.3^{+1.5}_{-1.3}$) is a significantly more active
starburst with a star-formation rate of 830$^{+340}_{-190}$M$_\odot$yr$^{-1}$
compared to MORA-9 ($z_{\rm phot}=4.3^{+1.3}_{-1.0}$) whose star-formation rate
is a modest 200$^{+250}_{-60}$M$_\odot$yr$^{-1}$. Based on the stellar masses
(M$_{\star}\approx10^{10-11}$M$_\odot$), space density
($n\sim(5\pm2)\times10^{-6}$Mpc$^{-3}$, which incorporates two other
spectroscopically confirmed OIR-dark DSFGs in the MORA sample at $z=4.6$ and
$z=5.9$), and gas depletion timescales ($<1$Gyr) of these sources, we find
evidence supporting the theory that OIR-dark DSFGs are the progenitors of
recently discovered $3<z<4$ massive quiescent galaxies.
