As part of the ongoing effort to characterize the low-mass ( sub ) stellar population in a sample of massive young clusters , we have targeted the \sim 2 Myr old cluster NGC 2244 .
The distance to NGC 2244 from Gaia DR2 parallaxes is 1.59 kpc , with errors of 1 \% ( statistical ) and 11 % ( systematic ) .
We used the Flamingos-2 near-infrared camera at the Gemini-South telescope for deep multi-band imaging of the central portion of the cluster ( \sim 2.4 pc ^ { 2 } ) .
We determined membership in a statistical manner , through a comparison of the cluster ’ s color-magnitude diagram to that of a control field .
Masses and extinctions of the candidate members are then calculated with the help of evolutionary models , leading to the first initial mass function ( IMF ) of the cluster extending into the substellar regime , with the 90 % completeness limit around 0.02 M _ { \sun } .
The IMF is well represented by a broken power law ( dN / dM \propto M ^ { - \alpha } ) , with a break at \sim 0.4 M _ { \sun } .
The slope on the high-mass side ( 0.4 - 7 M _ { \sun } ) is \alpha = 2.12 \pm 0.08 , close to the standard Salpeter ’ s slope .
In the low-mass range ( 0.02 - 0.4 M _ { \sun } ) , we find a slope \alpha = 1.03 \pm 0.02 , which is on the high end of the typical values obtained in nearby star-forming regions ( \alpha = 0.5 - 1.0 ) , but still in agreement within the uncertainties .
Our results reveal no clear evidence for variations in the formation efficiency of brown dwarfs and very low-mass stars due to the presence of OB stars , or for a change in stellar densities .
Our finding rules out photoevaporation and fragmentation of infalling filaments as substantial pathways for BD formation .