The origin of the lowest mass free-floating objects – brown dwarfs and planetary-mass objects – is one of the major unsolved problems in star formation .
Establishing a census of young substellar objects is a fundamental prerequisite for distinguishing between competing theoretical scenarios .
Such a census allows us to probe the initial mass function ( IMF ) , binary statistics , and properties of accretion disks .
Our SONYC ( Substellar Objects in Nearby Young Clusters ) survey relies on extremely deep wide-field optical and near-infrared imaging , with follow-up spectroscopy , in combination with Spitzer photometry to probe the bottom end of the IMF to unprecedented levels .
Here we present SONYC results for three different regions : NGC 1333 , \rho Ophiuchus and Chamaeleon-I .
In NGC 1333 , we find evidence for a possible cutoff in the mass function at 10-20 Jupiter masses .
In \rho Oph we report a new brown dwarf with a mass close to the deuterium-burning limit .