We report results of a re-analysis of archival Spitzer IRAC direct imaging surveys encompassing a variety of nearby stars .
Our sample is generated from the combined observations of 73 young stars ( median age , distance , spectral type = 85 Myr , 23.3 pc , G5 ) and 48 known exoplanet host stars with unconstrained ages ( median distance , spectral type = 22.6 pc , G5 ) .
While the small size of Spitzer provides a lower resolution than 8m-class AO-assisted ground based telescopes , which have been used for constraining the frequency of 0.5 - 13 M _ { J } planets at separations of 10 - 10 ^ { 2 } AU , its exquisite infrared sensitivity provides the ability to place unmatched constraints on the planetary populations at wider separations .
Here we apply sophisticated high-contrast techniques to our sample in order to remove the stellar PSF and open up sensitivity to planetary mass companions down to 5″ separations .
This enables sensitivity to 0.5 - 13 M _ { J } planets at physical separations on the order of 10 ^ { 2 } -10 ^ { 3 } AU , allowing us to probe a parameter space which has not previously been systematically explored to any similar degree of sensitivity .
Based on a colour and proper motion analysis we do not record any planetary detections .
Exploiting this enhanced survey sensitivity , employing Monte Carlo simulations with a Bayesian approach , and assuming a mass distribution of dn / dm \propto m ^ { -1.31 } , we constrain ( at 95 % confidence ) a population of 0.5 - 13 M _ { J } planets at separations of 100 - 1000 AU with an upper frequency limit of 9 % .