  We present results from a deep sub-millimeter survey in the Serpens Main and
Serpens/G3-G6 clusters, conducted with the Submillimetre Common-User Bolometer
Array (SCUBA-2) at the James Clerk Maxwell Telescope. We have combined Herschel
PACS far-infrared photometry, sub-millimeter continuum and molecular gas line
observations, with the aim to conduct a detailed multi-wavelength
characterization of `proto-brown dwarf' candidates in Serpens. We have
performed continuum and line radiative transfer modeling, and have considered
various classification schemes to understand the structure and the evolutionary
stage of the system. We have identified four proto-brown dwarf candidates, of
which the lowest luminosity source has an Lbol ~0.05 Lsun. Two of these
candidates show characteristics consistent with Stage 0/I systems, while the
other two are Stage I-T/Class Flat systems with tenuous envelopes. Our work has
also revealed a ~20% fraction of mis-identified Class 0/I/Flat sources that
show characteristics consistent with Class II edge-on disk systems. We have set
constraints on the mass of the central object using the measured bolometric
luminosities and numerical simulations of stellar evolution. Considering the
available gas+dust mass reservoir and the current mass of the central source,
three of these candidates are likely to evolve into brown dwarfs.
