A METHANE IMAGING SURVEY FOR T DWARF CANDIDATES IN {rho} OPHIUCHI

We report on the results of the first deep, wide-field, near-infrared methane imaging survey of the {rho} Ophiuchi cloud core to search for T dwarfs. Among the 6587 objects detected, 22 were identified as T dwarf candidates. Brown dwarf models indicate that at the age and distance of the {rho} Ophiuchi cloud, these T dwarf candidates have masses between 1 and 2 Jupiter masses. If confirmed as genuine T dwarfs, these objects would be the youngest, lowest mass, and lowest gravity free-floating objects ever directly observed. The existence of these candidates suggests that the initial mass function of the {rho} Ophiuchi cloud extends well into the regime of planetary mass objects. A large fraction (59% {+-} 16%) of our T dwarf candidates appear to be surrounded by circumstellar disks, and thus represents the lowest mass objects yet found to harbor circumstellar disks.