IZ photometry of Pleiades brown dwarfs

The survey extends up to 3{deg} from the cluster center and is 90% complete down to I~=22. It covers a mass range from 0.03M_{sun}_ to 0.48M_{sun}_ and yields 40 brown dwarf candidates (BDCs) of which 29 are new.

The spatial distribution of BDCs is fitted by a King profile in order to estimate the cluster substellar core radius. The Pleiades mass function is then derived across the stellar-substellar boundary and we find that, between 0.03M_{sun}_ and 0.48M_{sun}_, it is well represented by a single power-law, dN/dM{prop.to}M^-{alpha}^, with an index alpha=0.60+/-0.11. Over a larger mass domain, however, from 0.03M_{sun}_ to 10M_{sun}_, the mass function is better fitted by a log-normal function.