Substellar Objects in Nearby Young Clusters (SONYC). V. New Brown Dwarfs in ρ Ophiuchi

SONYC—Substellar Objects in Nearby Young Clusters—is a survey program to investigate the frequency and properties of substellar objects with masses down to a few times that of Jupiter in nearby star-forming regions. For the ~1 Myr old ρ Ophiuchi cluster, in our earlier paper we reported deep, wide-field optical and near-infrared imaging using Subaru, combined with Two Micron All Sky Survey and Spitzer photometry, as well as follow-up spectroscopy confirming three likely cluster members, including a new brown dwarf with a mass close to the deuterium-burning limit. Here we present the results of extensive new spectroscopy targeting a total of ~100 candidates in ρ Oph, with Fiber Multi Object Spectrograph at the Subaru Telescope and SINFONI at the ESO's Very Large Telescope. We identify 19 objects with effective temperatures at or below 3200 K, eight of which are newly identified very low mass probable members of ρ Oph. Among these eight, six objects have T eff