’ Isolated planetary mass objects ’ ( IPMOs ) have masses close to or below the Deuterium-burning mass limit ( \sim 15 M _ { \mathrm { Jup } } ) – at the bottom of the stellar initial mass function .
We present an exploratory survey for disks in this mass regime , based on a dedicated observing campaign with the Spitzer Space Telescope .
Our targets include the full sample of spectroscopically confirmed IPMOs in the \sigma Orionis cluster , a total of 18 sources .
In the mass range 8 \ldots 20 M _ { \mathrm { Jup } } , we identify 4 objects with > 3 \sigma colour excess at a wavelength of 8.0 \mu m , interpreted as emission from dusty disks .
We thus establish that a substantial fraction of IPMOs harbour disks with lifetimes of at least 2-4 Myr ( the likely age of the cluster ) , indicating an origin from core collapse and fragmentation processes .
The disk frequency in the IPMO sample is 29 \pm ^ { 16 } _ { 13 } % at 8.0 \mu m , very similar to what has been found for stars and brown dwarfs ( \sim 30 % ) .
The object SOri 70 , a candidate 3 M _ { \mathrm { Jup } } object in this cluster , shows IRAC colours in excess of the typical values for field T dwarfs ( on a 2 \sigma level ) , possibly due to disk emission or low gravity .
This is a new indication for youth and thus an extremely low mass for SOri 70 .