The bimodal initial mass function in the Orion Nebula Cloud
  Due to its youth, proximity and richness the Orion Nebula Cloud (ONC) is an
ideal testbed to obtain a comprehensive view on the Initial Mass Function (IMF)
down to the planetary mass regime. Using the HAWK-I camera at the VLT, we have
obtained an unprecedented deep and wide near-infrared JHK mosaic of the ONC
(90% completeness at K~19.0mag, 22'x28). Applying the most recent isochrones
and accounting for the contamination of background stars and galaxies, we find
that ONC's IMF is bimodal with distinct peaks at about 0.25 and 0.025 M_sun
separated by a pronounced dip at the hydrogen burning limit (0.08 M_sun), with
a depth of about a factor 2-3 below the log-normal distribution. Apart from
~920 low-mass stars (M < 1.4 M_sun) the IMF contains ~760 brown dwarf (BD)
candidates and ~160 isolated planetary mass object (IPMO) candidates with M >
0.005 M_sun, hence about ten times more substellar candidates than known
before. The substellar IMF peak at 0.025 M_sun could be caused by BDs and IPMOs
which have been ejected from multiple systems during the early star-formation
process or from circumstellar disks.
