Milky Way's young substellar population

Young clusters and star forming regions are home to a large number of substellar objects with masses below the hydrogen-burning limit at ~0.075 M⊙. Most of our knowledge about their populations comes from nearby regions (d<400 pc), where we find consistent formation rates of 2-5 young brown dwarfs per 10 newborn stars. Brown dwarf theories, on the other hand, predict that high gas or stellar densities, as well as the presence of massive OB stars, may be factors that boost the incidence of newly formed brown dwarfs with respect to stars. The next frontier in substellar studies, therefore, is the exploration of massive star clusters, characterized by significantly different star-forming environments than those found in our immediate vicinity. In this contribution I will compare the results of our deep survey SONYC (Substellar Objects in Nearby Young Clusters), with the brown dwarf content of several massive young clusters, in which we confirm the first bona fide brown dwarfs beyond 1 kpc. I will also discuss the trials and tribulations of membership confirmation in this mass and age regime.